Guest guest Posted February 23, 2005 Report Share Posted February 23, 2005 >>I know Armour PI says increase by 15mg every 2-3 weeks, can I go higher than that? And what level should I shoot for before agreeing to another blood test? Should I take part of it periodically during the day or all at once? Also, can you explain the benefit of taking it sublingually?<< It is best to increase SLOWLY, the 15MG every 2-3 weeks will get you there best! There is no RIGHT level to shoot for except what is exactly right for YOU, where you no longer have hypo symptoms but have no hyper symptoms either. That is another reason to increase slowly, so you don;t accidentally overshoot YOUR correct dosage. Armour should be taken at least twice a day, and some of us do best on even more often, that is trial and error for what is best for you too, but at least twice a day to start with. The benefit of sublingual is it is directly absorbed into the bloodstream without interference from poor digestion which is common in hypothyroidism, and less interference from what you have eaten or will eat in the next couple hours as it is absorbed from the stomach. *Artistic Grooming * Hurricane, WV Fat cat? Diabetes? Listowner for overweight or hypothyroid cats http://groups.yahoo.com/group/hypokitties/ Quote Link to comment Share on other sites More sharing options...
Guest guest Posted February 23, 2005 Report Share Posted February 23, 2005 >>I know Armour PI says increase by 15mg every 2-3 weeks, can I go higher than that? And what level should I shoot for before agreeing to another blood test? Should I take part of it periodically during the day or all at once? Also, can you explain the benefit of taking it sublingually?<< It is best to increase SLOWLY, the 15MG every 2-3 weeks will get you there best! There is no RIGHT level to shoot for except what is exactly right for YOU, where you no longer have hypo symptoms but have no hyper symptoms either. That is another reason to increase slowly, so you don;t accidentally overshoot YOUR correct dosage. Armour should be taken at least twice a day, and some of us do best on even more often, that is trial and error for what is best for you too, but at least twice a day to start with. The benefit of sublingual is it is directly absorbed into the bloodstream without interference from poor digestion which is common in hypothyroidism, and less interference from what you have eaten or will eat in the next couple hours as it is absorbed from the stomach. *Artistic Grooming * Hurricane, WV Fat cat? Diabetes? Listowner for overweight or hypothyroid cats http://groups.yahoo.com/group/hypokitties/ Quote Link to comment Share on other sites More sharing options...
Guest guest Posted February 23, 2005 Report Share Posted February 23, 2005 Just for your reference. 74 mcg of Synthroid is about equal to 1 grain of Armour. So, you current one grain of Armour is less than your Synthroid dose. 115 mcg of Synthroid = 1-1/2 grains of Armour 125 mcg of Synthroid = 1-2/3 grains of Armour You can increase as much as 1/2 of a grain at a time if you can stand it and don't develope some low adrenal problems, which are similar to hyper symtpoms. Other information that you might find useful to know is that the total daily output of the healthy thyroid is around 3 to 5 grains a day. If you have no adrenal problems and no nutritional deficitncies like anemia, you cannot overdose on any thyroid dose less than your own healthy thyroid would make. The reason for this has to do with the regulation of pituitary which works to prevent thyroid levels from going too high. So, if you take 1 grain of Armour, the pituitary will drop TSH by the amount needed to tell your thyroid to drop it's production by one grain or more keeping your daily total at or below 3 to 5 grains or whatever it is you need. A study done on healthy people found that the pituitary will zero out thyroid doses less than 3 to 5 grains. In other words doses less than 3 to 5 grains had absolutely no effect on the person due to the pituitary working to keep things exactly the same in the blood. Other studies have also shown that doses less than about a minimum of 3 grains seem to have no effect on blood levels of thyroid. In severly hypothyroid people, small doses of thyroid will have an effect of raising the metabolic rate, but this does not mean it makes them normal. So, the vast majority of people will not see much benifit from thyroid doses less than 3 grains. There are some lucky ones who can get by on less. 3 grains is 220 mcg of Synthroid. Doses of Synthroid as small as 50 mcg have been found to drop TSH into the normal range, yet harldy any thyroid patient feels good at this dose. Lots of studies have cast doubt on the usefullness of the TSH test for treating thyroid patients and adjusting doses. It is just not accurate. http://www.thyroid-info.com/articles/david-derry.htm http://www.suite101.com/article.cfm/graves_disease/98900 If you'd like to know a method youcan do on your own to adjust your meds and to know how well you are doing, check out these pages: http://www.drrind.com/tempgraph.asp http://www.thyrophoenix.com/self_monitor.htm Here are some articles that add to this: http://thyroid.about.com/library/derry/bl11.htm _____________________________ Statement from Dr. Derry in personal letter to a friend. The statement by C.P. Lalonde in 1948 review: " When thyroxine is administered to a thyroidectomized or myxedematous patient, it takes 250 -350 micrograms of thyroxine to maintain a normal metabolism. ( et al, 1935, Means, 1937) " C. P. Leblond. Iodine metabolism. Advanc Biol Med Phys 1:353-386, 1948. It does not say but I believe they gave it intravenously because it is so badly absorbed orally. But IV thyroxine works well. _____________________________ Author: Dr PBS Fowler Date Published: 23-May-2001 Publication: Lancet 2001; 357: 619-24. Volume 357, Number 9273 23 June 2001 Title: Letter in response to Colin Dayan's article ' Interpretation of thyroid function tests'. Before the days of hormone assays, hypothyroid patients received about double the average dose of thyroxine given today, but did not develop osteoporosis or atrial fibrillation. Doses should be judged clinically rather than be governed by misinterpreted hormone results. P B S Fowler 1 Dayan CM. Interpretation of thyroid function tests. Lancet 2001; 357: 619-24. __________________________________________________ Prognosis and treatment of COMMON THYROID DISEASES Proceedings of a Symposium held in San Francisco, California, U.S.A. - G March 1970 Editors : HERBERT A. SELENKOW AND FREDRIC HOFFMAN When treatment of hypothyroidism is initiated in adults who have been hypothyroid for several months or longer, small doses of hormone are generally used to minimize the risk of cardiovascular complications. The smallest dose of T4 which will cowistently lower serum TSH has been 50 ug per day (0.05 mg). We thus use this dose of medication as initial treatment dose and maintain it for 10- 14 days. The medication is then increased to 100 ug per day and kept there for a month in severely hypothyroid patients who are over 40 years of age. In younger individuals, more rapid increases may be used. Desiccated thyroid was a relatively reliable and very useful treatment for many years. During the past decade a number of reports appeared indicating that some preparations of desiccated thyroid might contain lowered activity or be inactive ( e t al., 1963; Brauerman and Ingbar, 1964; Catz et a].. 1962; Modell, 1964; Bartuska et dl., 1966). Such inactivity was considered to be due to one of the following causes: (I) deterioration of the drug on the pharmacy shelf, (2) batches of dry gland of low initial biological potency, or (3) failure of absorption of the densely packed tablets (Bartuska et dl., 1966). Since the serum levels of T3 are nearly unmeasurable, reproduction of the metabolic effects of the two hormones with T4 alone results in a higher serum T4 concentration than exists in the normal subject. T3 also has been used as replacement therapy for hypothyroidism. It is loosely bound to thyroxine-binding proteins in blood and has a shorter half- life. Thus, in the average patient requiring 280 ug T4 daily, 190 ug are absorbed. Of this, 90-100 ug replaces the T4 normally secreted daily and the remainder provides the physiological equivalent of normal T3 secretion. Objective and accurate assessment of adequate replacement dosage with thyroid hormone is difficult. The clinical impression provided by history is usually not an entirely accurate indicator, since relief of the profound symptoms of hypothyroidism produced by tiny doses of thyroid medications may be dramatic. Physical examination is helpful, but it is often not possible by this means to distinguish a minimally hypothyroid individual from a euthyroid one. Moreover, the range of thyroxine concentrations in normal subjects is wide and varies with age (Oddie and Fisher, 1967) and sex (Oddie et al., 1966). It is difficult to assess what is the optimal dose for any one subject, for at present we have no objective, easily quantifiable parameter to assess response of body tissues to thyroid hormone replacement. Measurements of serum TSH, kinetics of reflex time, and oxygen consumption are helpful, but not entirely reliable for this purpose. SELENKOW: I primarily follow my patients clinically. The laboratory tests are most useful in confirming euthyroidism once the maintenance dosage of thyroid has been attained. SELENKOW: ...if the patient is only on one of the commercial sodium levothyroxine preparations (either Synthroid or Letter), the free thyroxine index is also not applicable. Individuals on physiological replacement doses of pure sodium levothyroxine have elevated levels (high normal to hyperthyroid range) of serum thyroxine (-Pattee). The resin uptake tests in these persons are also elevated above normal, so that in patients on 300 or 400 pg of sodium levothyroxine a day, the PBI or serum thyroxine level will be in the high range and so will the free thyroxine index. On physiological doses of desiccated thyroid, USP or on Liotrix (Euthroid, Warner-Chilcott) the serum levels of all thyroid function tests will more closely relate to what you expect in a normal euthyroid person. BURKE: I will not repeat the truism that the most reliable index of response to therapy is the clinical status of the patient, but this really should be emphasized,... BECKER: I would like to emphasize what Dr. Odell has said. I believe that the physician must pay close attention to the patient. GREENSPAN: Dr. Becker, you have done a noble job in resurrecting the ghost of the BMR. One of the big problems in measuring the tissue effect of T4 is that we really do not know the exact mechanism of action of thyroxine. Overall oxygen consumption must be really a very late effect of high levels of circulating thyroxine. If we had some way of measuring more precisely the effect of thyroxine on a specific tissue, we would have a better and more precise method for measuring its tissue effects. A dose of T4 of about 20 ug/kg body weight will usually produce good results in newborns. It is not necessary to initiate treatment with small doses as is done in adults. Circulating thyroxine should be measured periodically and in infants and small children should be maintained at 9-15 ug/100 ml (as thyroxine iodide 6-10 ug %). In addition, growth rate and bone age should be followed serially. Inadequate replacement will result in slowing of growth rate and delay in bone maturation. _____________________ http://thyroid.about.com/library/derry/bl3a.htm Dr. Derry Chronic fatigue symptoms of low temperatures, fatigue and accompanying brain fog are classical signs and symptoms of hypothyroidism. (1-3) There are many psychological symptoms and personality difficulties which accompany brain dysfunction related to hypothyroidism many of which have been published in a classical 1958 publication. (3) One of the most prominent is loss of self- esteem and inability to cope properly. The doses a patient gets when monitored by the TSH is currently two thirds or less of the well established clinically effective doses established from 83 years of clinical experience before the TSH arrived. (5-6) ff and LoPresti (7) discussed this problem in their conclusions: " It may be that the critical events controlling thyroid hormone action in non-thyroidal illness (all illness not related to thyroid) are largely regulated at the cellular level and that we are naive to believe that we can make interpretations from circulating thyroid hormones values. " (7) So the human body can operate at all the different levels of thyroid hormone. But at the low levels function is poor. At the correct levels the patient copes well and does well. Repeatedly, studies on normal people with increasing doses of thyroid found humans have a wide range of tolerance for thyroid hormone (8-11). All body tissues, including the brain can adapt individually to the higher or lower levels of thyroid hormone Because all organs can adapt to many levels of thyroid hormone it suggests that for each person there is an individual level at which this person can cope and function at optimal levels. (5) For example, in a sixteen part study of the effects of desiccated thyroid on healthy prisoners Danowski et al found they tolerated dosages of 9 grains of desiccated thyroid (540 mgs which equals about 540 micrograms thyroxine) without ill effects. (9-11). On studies on obesity and thyroid hormone where the dosages for three months were between three grains and 25 grains (1500 mg of desiccated thyroid equals about 1500 micrograms of Eltroxine) (12). they said: " As in previous studies, these dosages of desiccated thyroid were well tolerated by the subjects. Occasional nervousness, increased sweating, and decreased endurance were reported. Tachycardia and slight increase in the systolic blood pressure and decreases in the diastolic blood pressure appeared in all. Electrocardiogram changes were minimal. Body weight decreased by an average of 26 pounds during the 22 weeks of treatment. " (7). ________________________ [study of hormone replacement therapy following total thyroidectomy in thyroid cancer--with special reference to the analysis of thyroid hormone peripheral effects, using indirect calorimetry] [Article in Japanese] Nozaki H, Funahashi H, Sato Y, Imai T, Oike E, Kato M, Takagi H. Second Department of Surgery, Nagoya University School of Medicine, Japan. Five weeks after the beginning of hormone replacement, T4 and free T4 were slightly within range, and no enhancement of energy metabolism was noted. From these findings, the post-operative TSH suppression therapy carried out at our department is considered to be justifiable also from the viewpoint of energy metabolism. (dangers of long lasting low energy states from inadequate thyroid - body does not respond to treatment after it has been hypo for too long.) __________________________ From " Thyroid Guardian of Health " by G. Young It is an important guidline in that if individuals are placed on and excessive dose of thyroid hormone, the temperature should become elevated within two weeks time. However, if the thyroid feedback mechanisms are working properly it is impossible to make and individual hyperthyroid untill they are given more thyroid that the gland produces--about 4-1/2 grains for a small individual and about 5 grains for the usual adult. Their basal temperature should rise up over 98.2 deg F if they are truely hyperthyroid, and thus have too much thyroid hormone. The pulse is important as well; a slow pulse is typical of pure low thyroid condition. With low adrenal function, the pulse speeds up and the rapid pulse may indicate inadequate adrenal support. The blood pressure is also an important guid line. A blood pressure with a systolic below one hundred indicates inadequate adrenal support...... Some authorities believe that if autoantibodies are present, it renders other thyroid testing invalid. Clinical symptoms remain the best indicator of adequate dosage. ________________________ http://www.drlowe.com/QandA/askdrlowe/armourthyroid.htm That optimal dosage range is highly individual, but historically, the typical patient's therapeutic window has been somewhere between 120 to 240 mg (2 to 4 grains). There's no way to accurately predict what your therapeutic window is. _____________________ Dr. Derry, " Breast Cancer and Iodine " : Before the 1973-1974 change in laboratory diagnosis, the objective of treatment in all cases was raise the thyroid dose up untill the patient was in a state of well-being. Before the 1973-74 change, the normal dose of thyroid was three times the level seen now (2 -3 grains now) and there were no cases of fractures or osteoporosis ever reported in the previous 80 years. _________________________________ Dr. Barry Peatfield from his book " The Great Thyroid Scandal " Page 87-88: The disgraceful fact is that all these measurements (except the last) may not be worth the paper they are written on; or may be so flawed that treatment based on them is bound to be wrong. So what goes wrong? And why are doctors not aware that they may be so badly off the beam? And why do so many have minds so closed? The reasons blood tests may be so flawed we need now to examine. First and foremost these are measures only of the levels of thyroid hormone in the blood. What we need to know is the level of thyroid in the tissues, and, of course, this the blood test cannot tell us. The nearest we can go is the Basal Temperature Test, or the Basal Metabolic Rate. The first we have discussed; the second is now of historical value. The patient is connected up to an oxygen uptake, carbon dioxide excretion, measuring device, and the rate of usage determines the metabolic rate. This is also subject to various errors. The amount of thyroid hormones being carried by the bloodstream varies in a highly dynamic way, and may be up at one point and down the next. The blood test is simply a two-dimensional snapshot of the situation at that moment. The slowed circulation may cause haemo-concentration from fluid loss, so that the thyroid levels are higher than they should be. (A simple way to explain this is to think of a spoonful of sugar in your cup of tea. If it is only half a cup of tea but you still put in your teaspoon of sugar, then although the amount of sugar is the same, the tea will be twice as sweet.) But the blood levels depend mostly on what's happening to the thyroid hormones. If the cellular receptors are sluggish, or resistant, or there is extra tissue fluid, together with mucopolysaccharides, the thyroid won't enter the cells as it should; so that part of the hormone is unused and left behind, giving a falsely higher reading to the blood test. It is simply building up unused hormone. This may apply to both T3 and T4. Further complications exist if the T4 + T3 conversion is not working properly, with a 5'-diodinase enzyme deficiency. There will be too much T4, and too little T3. If there is a conversion block, and a T3 receptor uptake deficiency, both T3 and T4 may be normal or even raised. The patient will be diagnosed as normal or even over-active; in spite of all other evidence to the contrary. It grieves me to report that I have intervened several times to prevent patients, diagnosed as hyperthyroid, having an under-active thyroid removed when the only evidence was the high T4 level (due to receptor resistance) and the patient was clinically obviously hypothyroid. The patients thanked me, but not the consultants. Adrenal insufficiency adds another dimension for error to the T4 and T3 tests. Adrenal insufficiency, of which more anon, will adversely affect thyroid production, conversion, tissue uptake and thyroid response. It may make a complete nonsense of the blood tests. The most commonly used test of all is the TSH. I have sadly come across very few doctors who can accept the fact that a normal, or low TSH may still occur with a low thyroid. The doctrine is high TSH = low thyroid. Normal TSH = normal thyroid. But the pituitary may not be working properly (secondary or tertiary hypothyroidism). It may not be responding to the Thyrotrophin Release Hormone(TRH) produced by the hypothalamus, which itself may not be producing enough TRH for reasons we saw earlier. The pituitary may be damaged by the low thyroid state anyway, and be sluggish in its TSH output. ______________________________ MINI REVIEW Intrinsic imperfections of endocrine replacement therapy J A Romijn, J WA Smit and S W J Lamberts Department of Endocrinology, Leiden University Medical Center, Leiden and Department of Internal Medicine, Erasmus Medical Center, Rotterdam University, Rotterdam, The Netherlands (Correspondence should be addressed to J A Romijn; Email: j.a.romijn@...) However, many patients treated for endocrine insufficiencies still suffer from more or less vague complaints and a decreased quality of life. It is likely that these complaints are, at least in part, caused by intrinsic imperfections of hormone replacement strategies in mimicking normal hormone secretion. ......effects of hormones in general, and thus of hormone replacement strategies in particular, are difficult to quantify at the tissue level. Therefore, in clinical practice we rely mostly on plasma variables – `plasma endocrinology' – which are a poor reflection of hormone action at the tissue level. Complaints of thyroid patients....They range from musculoskeletal complaints, to vague feelings of being unwell, and to depression. Two approaches have been used to decrease the complaints experienced by these patients: an increase in the dose of L-thyroxine, and combination treatment of thyroxine with tri-iodothyronine. In some of the patients, a decrease in complaints can be achieved by increasing the dose of thyroxine above that required to restore TSH concentrations to normal (1). For this reason, such patients are often allowed to take a dose of thyroxine that would be judged as overtreatment with respect to TSH concentrations. The second approach was evaluated by Bunevicius et al. (2), who performed a randomised controlled trial to compare the effects of thyroxine alone with those of thyroxine plus tri-iodothyronine. Patients with hypothyroidism benefitted when 12.5 mg triiodothyronine was substituted for 50 mg thyroxine in their treatment regimens. This resulted in improved neuropsychological functioning. Pulse rates and serum sex hormone-binding globulin concentrations were greater after treatment with thyroxine plus tri-iodothyronine, indicating a slightly greater effect on the heart and liver. Serum thyroxine concentrations were lower and tri-iodothyronine concentrations were greater after treatment with thyroxine plus tri-iodothyronine, but serum TSH concentrations, a sensitive measure of thyroid hormone action, were similar after the two treatments. It should be noted that not all patients benefitted from this approach because, even in the group with combination therapy, patients continued to report complaints of depression. Thyroxine: The thyroid secretes tri-iodothyronine (T3) (,20%) in addition to thyroxine (T4) (,80%). In the absence of thyroid function, exogenous thyroxine is not able to normalise the concentrations of T4 and T3 in all tissues in rodents, even in the presence of normal TSH concentrations. Despite this knowledge, currently available preparations of T3 have unfavourable pharmacological profiles and adequate markers of biological effect are lacking. Additional evidence is required before combination therapy can be advised. First, it is remarkable that the normal values of TSH show a more than tenfold variation, between 0.4 and 4.5mU/l. Because, in clinical practice, the optimal TSH concentration for individual patients within this range is unknown, titration of the substitution dose of thyroxine within this tenfold variation is relatively crude. Secondly, the intrinsic assumption of many doctors in this approach is that normal TSH concentrations reflect adequate thyroid hormone concentrations, not only at the tissue level of the hypothalamus and the pituitary, but also in the other tissues. However, it is likely that this assumption is erroneous, because TSH is produced only by the pituitary gland and therefore may not reflect thyroid hormone status in tissues outside the hypothalamo– pituitary axis. This notion is supported by data obtained from animal experiments. Thyroxine is considered to be an inactive hormone, because a thyroxine-specific receptor has not been identified. Rather, thyroxine serves as a prohormone, because it is the precursor of tri-iodothyronine. Some tissues, such as muscle, have a relatively low deiodinase activity and are dependent, to a great extent, on tri-iodothyronine derived from the thyroid and the liver. In rodents, it has been clearly demonstrated that there is no single dose of thyroxine or tri-iodothyronine that normalises thyroid hormone concentrations in all tissues simultaneously in hypothyroid animals (3). Therefore, it is highly likely that, in patients treated with L-thyroxine, subtle derangements at the tissue level are present with respect to thyroid hormone availability, and probably also thyroid hormone action. _______________________ A very good article by Dr. Lowe stating that some patients, especially those with auto-immune thyroid disease need TSH suppressive (high) doses of thyroid hormone to have good health. http://www.drlowe.com/frf/t4replacement/intro.htm The most effective of these therapies involves adjusting patients' dosages of combined T4/T3 or T3 alone according to several indices other than TSH and thyroid hormone levels. Those indices are signs, symptoms, and various objective measures of tissue response to particular dosages. When patients' dosages are titrated according to these indices, dosages that prove safe and effective are typically TSH-suppressive.[44] Evidence is available that this therapeutic approach relieves patients' signs, symptoms, and measurable tissue abnormalities such as low resting metabolic rates (RMR) according to indirect calorimetry. This observation suggests that dosages higher than those dictated by the replacement concept more effectively relieve patients' hypothyroid symptoms. Other research has shown that patients report feeling better with TSH-suppressive dosages of thyroid hormone.[23] [24][25] Moreover, psychiatrists report that dosages of T3 higher than replacement dosages augment the depression-relieving effects of antidepressants.[9][28][29][30][31][34] In addition, in a study of patients made hypothyroid by therapeutic destruction of the thyroid gland, some used TSH-suppressive dosages of thyroid hormone and others used T4-replacement. Those on TSH-suppressive dosages didn't gain excess weight; those on T4-replacement did. The researchers concluded that T4-replacement was the cause of the excess weight gain.[55] These published reports are consistent with thousands of cases in which hypothyroid patients recovered from their symptoms and other health problems with TSH-suppressive dosages of thyroid hormone after T4-replacement failed to help them. Kaplan's observation also suggests another point: that T4- replacement keeps many hypothyroid patients' dosages too low to relieve their symptoms is an indictment of the concept of replacement. As the cause of (1) the continued suffering and debility of patients, (2) an increased incidence of potentially life-threatening diseases, and (3) the need for the chronic use of medications, ___________________________ Dr. Derry article: http://thyroid.about.com/library/derry/bl11.htm The effective dose physicians used by clinical judgment and experience before 1975 was around 2-3 times higher than the dose used by TSH blood test monitoring. So everyone's dose of thyroid after 1975 was decreased by about two thirds of well established clinically effective doses. *********************** Another Derry article: http://thyroid.about.com/library/derry/bl4a.htm In the 1960s it was textbook material after 70 years of experience using thyroid that a dose below 180 mg of desiccated thyroid (3 grains) could not be measured clinically or in the laboratory. In other words it was without effect.(2) The approximate equivalent dose of synthroid or thyroxine (T4) would be about 180 micrograms. (3) So unless your dose is above 180 there is little chance of regaining your hair back and the problem likely continue and get worse. You can tell when you are approaching the right dose personally when the itching starts to go away permanently. Depending on how old you are and other medical history it is likely though you would get complete relief with a dosage up around 200 micrograms of Synthroid or higher. We know that there are no side effects at those dosages. Dosages of thyroxine (Synthroid, T4) of up to 300 micrograms are without morbidity or mortality. (no sickness or deaths) (4) _____________________________ Dr. Lowe's wife: http://www.drlowe.com/emailnewsletter/2003archive.htm Instead, they adjust dosages according to how patients respond to a particular dose. As studies have shown, this approach produces far superior treatment results than does adjusting dosages according to thyroid test results.[1][2] ________________________ Dr. Lowe uses this guide: http://www.drlowe.com/clincare/clinicalforms/areyouoverstimulated.pdf to determine if the patient is on too high a dose. In other words, they raise thyroid dose up untill the patient feels best and use this form as a way to make sure they haven't gone too high. Dose is determined purely by how the patient feels and no tests are used _____________________ (This article show that people got no response to thyroid hormone at doses less than 3-5 grains) Author: MONTE A. GREER, M.D. Date Published: 15-Mar-1951 Publication: The New England Journal of Medicine Volume 244 MARCH 15, 1951 Number 11 Title: THE EFFECT ON ENDOGENOUS THYROID ACTIVITY OF FEEDING DESICCATED THYROID TO NORMAL HUMAN SUBJECTS Category: research Keywords: research, GREER, EFFECT, ENDOGENOUS, THYROID, ACTIVITY, FEED, DESICCATED, NORMAL, HUMAN, SUBJECT, circulating, thyroxin, thyrotrophin, radio, iodine, index, therapeutic, accurate, euthyroid Text: 388 IT HAS been known for many years that a reciprocal relation appears to exist between the levels of circulating thyroxin and thyrotrophin in the vertebrate species so far investigated, Until recently, however, direct tests of thyroid actiyity in man have not been feasible. Within the last few years, radioactive iodine has provided a new method .for the study of thyroid function, permitting observations that would otherwise be impossible. Using shielded G-M counters, it is possible to follow directly the accumulation of radioiodine in the thyroid gland. Studies in several clinics have indicated that this method is an accurate index of thyroid function. In view of the widespread therapeutic use of thyroid medication, it was of interest to determine whether the administration of physiologic amounts of the hormone to man would produce the same compensatory depression of the thyroid gland as that observed in laboratory animals. Previous investigators, using other measures of thyroid function, have observed that the thyroid gland is depressed by thyroid feeding. Farquharson and Squiresl found that the administration of moderate doses of desiccated thyroid to apparently euthyroid " hypometabolic " subjects produced no appreciable elevation of the initially low basal metabolic rate. On the contrary, when thyroid medication was stopped, the basal metabolic rate fell rapidly below the pretreatment level and remained depressed for several weeks before gradually rising up the initial level. Riggs and his co-workers2 administered gradually increasing amounts of thyroid up to 20 to 25 gr. dally to euthyroid subjects. It was found that both the basal metabolic rate and the serum-precipitable iodine remained relatively constant until daily doses in excess of 3 to 5 gr. were given, when both. indices of thyroid activity began to rise co-comltantly. When the admmlstratlon of thyroId was abruptly stopped, the basal metabolic rate and serum-precipitable iodine fell abruptly, but transiently, to abnorncally low levels, indicating an inhibition of endogenous hormone production and a delayed return to normal thyroid function. The present investigation was designed primarily to determine how rapidly depression of the normal human thyroid gland occurs after the institution of daily physiologic doses of thyroid hormone, how much hormone is required daily to produce complete depression of the thyroid and how rapidly recovery of thyroid activity occurs after the cessation of therapy. MATERIALS AND METHODS Fortv-seven normal human volunteers, consisting chiefly of laboratory technicians, physicians and nurses, were employed. They were between 17 and 67 years of age, and all but three were women. All were clinically euthyroid so far as could be determined, although basal metabolic rates were obtained in only a few instances. About one fourth of the subjects had taken thyroid previously at one time or another; three had stopped the hormone only a few weeks before beginning the. experiment. Four had been taking 3 or more grams daily for several years, the initial study of all but one of these being made while they were still taking the hormone. Studies with radioactive iodine were made wIth a modification of the technic devIsed by Astwood and Stanley.3 The isotope with an eight day half-life, I131, was used. Following the admistratlon of a 50- microcurie tracer dose of I13l, serIal counts were made over the thyroid gland by means of an externally placed shieided gamma counter. Since the 24-hour uptake had been found to be as relIable as any index of thyroid function determined by eans of I131 only this measurement was used. The Il31 was obtained from Oak RIdge; the standardization made at that laboratory before shipment was accepted. An amount of radic:active iodine approximating 50 microcuries. was pipetted into a 50-cc. Erlenmeyer flask and diluted wIth 15 to 20 ml. of tap water. The flask was then placed in front of the shielded gamma counter, and the absolute quantity of radioactivity determined. The distance of the flask from the end of the gamma tube was measured by a ruled steel slide, at the edge of the shielding, which was connected to a thin 389 thyroid function, although without clinical evidence of hypothyroidism, was associated with normal levels of circulating thyroxin. It is interesting that subjects who had been taking desiccated thyroid for several years showed as rapid a return of thyroid function as did those subjects who had been taking the drug only a few days. This strongly indicates that chronic depression of the thyroid gland produces no permanent injury. One other interesting feature is that a " rebound " phenomenon seems concomitant with the return of the depressed thyroid glands to normal. This was especially evident in the continuously treated subjects,; two had uptakes higher than 50 per cent in the first swing of recovery, which subsequently dropped below this level. Uptakes of from 50 to 75 per cent have been observed in 5 other patients after withdrawal of thyroid hormone, which they had been taking for several years, but these were not included in the present study because only a single determination of their thyroid function was made. This rebound is presumably due to a lag in the adjustment of pituitary thyrotrophin production. The depressed pituitary may be stimulated to increased secretion of thyrotrophin as the level of circulating thyroxin falls upon cessation of therapy. However, there is perhaps a certain lag before the pituitary again becomes inhibited by increased endogenous thyroid secretion, the thyroid gland thus becoming overstimulated. This same type of delayed readjustment is probably responsible for the fall in basal metabolic rate and serum-precipitable iodine seen after the withdrawal of exogenous thyroid. It is possible that the occasional case of thyrotoxicosis seen to develop upon the withdrawal of thyroid medication from euthyroid patients may be partially explained on this basis. ..... The data presented indicate that the administration of exogenous thyroid hormone results in a corresponding depression of endogenous thyroid function, whatever the mechanism by which this is produced. Since it has been found that the serum-precipitable iodine and the basal metabolic rate do not rise in normal subjects unless thyroid in excess of 3 to 5 grains daily is given, it seems reasonable to assume that astable euthyroid level of circulating thyroxin is maintained by a depression of endogenous hormone formation equivalent to the amount administered. This stable level is probably maintained through pituitary regulation. The administration of small doses of thyroid to normal patients for the control of obesity, menstrual disturbances, " fatigue " and so forth would thus seem to be without reason or promise of therapeutic effect, since excessive amounts would be required before any elevation of the levels of circulating thyroxin and basal metabolic rate could be produced. The doses commonly administered for these disorders are certainly below what would be considered toxic levels, and the only effect to be expected would be a compensatory depression of endogenous thyroid activity. The disappointing experiences of clinicians in their attempts to treat apparently euthyroid patients for such disorders are thus readily explained. The occasional patient who complains of symptoms of hyperthyroidism while taking only 3 to 4 grains of thyroid daily may represent those persons whose thyroid glands become markedly depressed by the exhibition of 1 gr. or less of hormone daily. Three grains would thus be 390 three times their daily requirements; this might possibly give rise to symptoms of overdosage. It is of interest to consider the " increased sensitivity " of myxedematous patients to exogenous thyroid hormone. This supposition seems to have existed since the days of the first successful treatment with thyroid extract of patients with Gull's Disease. So far as the author is aware, no evidence has been published that establishes any difference in the tissue susceptibility to thyroid hormone of euthyroid subjects from that of myxedematous subjects. It is frequently stated that myxedematous patients show signs and symptoms of " toxicity " at lower dosage levels than do those with normal thyroid glands, but adequate data supporting this statement have never been presented. There is no question that small doses of hormone have a much greater effect in raising the basal metabolic rate and relieving the evidences of hypothyroidism in myxedematous than in euthyroid-patients. This is readily explained by the necessity for first equaling endogenous hormone production before any elevation of the basal metabolic rate can be produced in normal subjects. Riggs and his co-workers2 seem to be correct in assuming that the failure of the serum-precipitable iodine to rise until 3 to 5 grains of thyroid were administered daily to normal subjects was due to the necessity of first depressing endogenous thyroid activity. However, they stated that this did not adequately explain the differences between the two groups, since hypothyroid patients became " toxic " on such low doses that they could not obtain data equivalent to that on euthyroid patients who took large doses. They suggested that the thyroid gland in intact patients is capable of " breaking down " thyroid hormone, an explanation that seems unlikely in view of the evidence of Leblond and Sue7 that the thyroid gland is incapable of concentrating organically bound, iodine and that it is only when the element is available as inorganic iodide that accumulation is possible. Certainly the evidence presented by Riggs2. 8 indicated little difference in the responses of subjects with and without thyroid glands, since the basal metabolic rate increased as much for an equivalent rise in serum-precipitable iodine in normal persons as in those with myxedema. As gradually increasing doses of thyroid are given to patients with myxedema, there is a progressively diminishing augmentation of the basal metabolic rate as it approaches normal. Thus, 1 grain of thyroid taken daily will produce a much greater increment in the basal metabolic rate of an untreated myxedematous patient with a basal metabolic rate of -30 per cent than it will in a myxedematous patient already being treated with 1 grain daily who has a basal metabolic rate of -10 per cent. If the basal metabolic rate is plotted against the dose of thyroid given in myxedematous patients, a curve is seen that approaches a plateau as the metabolism returns to normal.9 It seens quite possible that if this curve were extended and thyroid given in doses equivalent to the 5 to 25 gr. administered by Riggs to normal subjects, no difference would be found between subjects with and those without thyroid glands. It would be expeeted that much larger doses of thyroid would be required to produce an equivalent rise of the metabolic rate if the subject were near the euthyroid level before treatment was begun. Such has in fact been found to be the case in investigations of intact subjects. SUMMARY The effect of exogenous thyroid hormone on the endogenous thyroid function of 47 normal human subjects has been investigated with the use of radio-active iodine. Marked depression of the subject's thyroid gland could be produced within one week by the administration of adequate daily physiologic doses of hormone. The daily amount of hormone required to produce marked thyroid depression was between land 3 grains in 93 per cent of those studied, although one girl required 9 grains. After the withdrawal of therapy, thyroid function returned to normal in most subjects within two weeks, although a few subjects showed depression for six to eleven weeks. Thyroid function returned as rapidly in those subjects whose glands had been depressed by several years of thyroid medication as it did in those whose glands had been depressed for only a few days. Thus no permanent injury to the thyroid gland seems to be produced by long-continued hormone administration. It is felt that the reduction in endogenous thyroid function was brought about through a depression of pituitary thyrotrophin secretion. It is suggested that no important difference in sensitivity to thyroid hormone exists between athyreotic and intact subjects. REFERENCES I. Farquharson, R. F., and Squires. A. H. Inhibition of secretion of thyroid gland by continued ingestion of thyroid substance. Tr. Am. Physicians 56:87-97, 1941. 2. Riggs, D. S.. Man, E. B., and Winkier, A. W. Serum iodine of euthyraid subjects treated with desiccated thyroid. j. Clin. lnvestigalion 24:722-731, 1945. 3. Astwood. E. B., and Stanley, M. M. Use of radioactive iodine a study of thyroid function in man. West. j. Surg. 55:625-639. 1947. 4. Cortell. R., and Rawson, R. W. Effect of thyroxin On response of thyroid gland to thy,otropic hormone. Endocrina/ogy 35:488-498. 1944. 5. Stanley, M. M.. and Astwood, E. B. Response of thyroid gland in normal human subjects to administration of thyrotropin, as shown by Studies with II " . Endocrinology 44:49-60. 1949. 6. Stanley, M. M. Direct estimation of rate of thyroid ho,mone formation in man: effect of iodide ion on thyroid iodine utilization. j. C/in Endocrino/. 9:941-954, 1949. 7. Le blond, C. P., and Siie, P. Iodine fluctation in thyroid as influenced by hypophysis and ulher factors. Am. j. Physiol. 134:549- 561, 1941. 8. Winkier, A. W., Riggs, D. S., and Man. E. B. Serum iodine in hypothyroidism before and during thyroid therapy. J. Clin. lnvestigalion 24:732-741.1945. 9. Means, ]. H., and Lerman, ]. Symptomatology of my:tedema: its relation to metabolic levels. time intervals and rations of thyroid. Arch. lnt. Med. 55:1-6, 1935. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted February 23, 2005 Report Share Posted February 23, 2005 Thanks to all for the valuable information - I'll start taking the Armour sublingually, and try to convince the doctor that I know what I'm doing (with everyone's help) so he'll let me increase the dosage on my own until I feel better. Unfortunately at the rate of 15mg every 3 weeks, I'm going to feel pretty bad for a while, I just hope it's worth it in the long run! Thanks everyone - I'll let u know how it goes - I can always find another doctor, right? Joyce > > > 115 mcg of Synthroid = 1-1/2 grains of Armour > > 125 mcg of Synthroid = 1-2/3 grains of Armour > > I wanted to also squeeze myself in here and tell you that though > Tish put the conversion amounts above, you will need much more of > Armour than the above to rid yourself of symptoms...as she later > talks about. I was on .125 Synthroid, and my optimal dose ended up > being 3 grains.........and I am now on 3 1/4 grains. > > Janie Quote Link to comment Share on other sites More sharing options...
Guest guest Posted February 23, 2005 Report Share Posted February 23, 2005 Thanks to all for the valuable information - I'll start taking the Armour sublingually, and try to convince the doctor that I know what I'm doing (with everyone's help) so he'll let me increase the dosage on my own until I feel better. Unfortunately at the rate of 15mg every 3 weeks, I'm going to feel pretty bad for a while, I just hope it's worth it in the long run! Thanks everyone - I'll let u know how it goes - I can always find another doctor, right? Joyce > > > 115 mcg of Synthroid = 1-1/2 grains of Armour > > 125 mcg of Synthroid = 1-2/3 grains of Armour > > I wanted to also squeeze myself in here and tell you that though > Tish put the conversion amounts above, you will need much more of > Armour than the above to rid yourself of symptoms...as she later > talks about. I was on .125 Synthroid, and my optimal dose ended up > being 3 grains.........and I am now on 3 1/4 grains. > > Janie Quote Link to comment Share on other sites More sharing options...
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