Testosterone/Growth Hormone Deficiency (Thyroid)

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Testosterone

Low testosterone in men will result in a lowering of D1

activity without changing pituitary D2 (1). Thus, a drop in testosterone will

result in lower tissue levels of T3 without producing an elevation of TSH (1, 2).

Environmental factors, including pesticides, plastics, and other pollutants,

have resulted in a significant decrease in the average testosterone levels for

men, so most men will have, at least, a relative deficiency of testosterone (3).

Major laboratories have, unfortunately, reduced the “normal” range

of free testosterone to maintain the 95 percentile as normal, the result being

that many abnormally low levels will now be considered normal.

In

particular, the majority of male diabetics and those with insulin resistance

will have suppressed testosterone level that is in the low or low-normal range,

which further suppresses D1 and tissue T3 levels and perpetuates the weight

gain or inability to lose weight — worsening of these conditions ((4-6)

Growth

hormone

Growth

hormone deficiency reduces T4 to T3 conversion and increases reverse T3 while

supplementation with growth hormone improves T4 to T3 conversion and reduces

reverse T3 (7,233,281,282). The age-associated decline in growth hormone

certainly contributes to the reduced T3 levels with age not detected by TSH and

T4 testing (see thyroid

hormones and aging graph).

1.

Miyashita

K, Murakami M, Iriuchijima T, Takeuchi T, Mori M. Regulation of rat liver type

1 iodothyronine deiodinasemRNA levels by testosterone. Mol Cell Endocrinol

1995;115:161–167

2.

AR, Vagenakis AG, Braverman LE. Sex-related differences in outer ring

monodeiodination of thyroxine and 3,3_,5_- triiodothyronine by rat liver

homogenates. Endocrinology 1979;104: 645–652.

3.

Kupelian

V, FJ, Link CL, et al. Inverse association of testosterone and the

metabolic syndrome in men is consistent across race and ethnic groups. J Clin

Endocrinol Metab 2008;93:3403–3410.

4.

Kapoor

D, Aldred H, S, Channer KS, TH. Clinical and biochemical assessment

of hypogonadism in men with type 2 diabetes: Correlations with bioavailable

testosterone and visceral adiposity. Diabetes Care 2007;30(4):911-7.

5.

Makhsida

N, Shah J, Yan G. Hypogonadism and metabolic syndrome: Implications for

testosterone therapy. J Urology 2005;174:827-834.

6.

nsen

JOL, Pedersen SA, Laurberg P, Weeke J, et al. Effects of growth hormone therapy

on thyroid function of growth hormone-deficient adults with and without

concomitant thyroxine-substituted central hypothyroidism. J Clin Endocrinol

Metab 1989;69:1127-1132

7.

Van

der Geyten S, Buys N, JP, Decuypere E, et al. Acute pretranslational

regulation of type III iodothyronine deiodinase by growth hormone and

dexamethasone in chicken embryos. Mol Cell Endocrinol 1999;147:49–56.

8.

Silva

JE, Larsen PR. Interrelationships among thyroxine, growth hormone, and the

sympathetic nervous system in the regulation of 5-iodothyronine deiodinase in

rat brown adipose tissue. J Clin Invest 1986;77:1214-1223.

9.

Darras

VM, Berghman LR, Vanderpooten A, Kuhn ER. Growth hormone acutely decreases type

III deiodinase in chicken liver. FEBS Lett 1992;310:5-8.

10. Takser L, Mergler D,

Baldwin M, de Grosbois S, et al. Thyroid hormones in pregnancy in relation to

environmental exposure to organochlorine compounds and mercury. Environmental

Health Perspectives 2005;113(8):1039-1045.

http://nahypothyroidism.org/deiodinases/#iron deficiency