Re: Qustion about sweat test

[Guest guest]

Hi Deranda,

I feel so sorry for you that you have to deal with such a doc. To

quote Albert Einstein " Only two things are endless, human stupidity

and the universe, but I am not sure about the latter " .

I have copied two articles below about that subject. Normal sweat

tests may be rare, but they are existent and it is ridiculous to

exclude further tests until there is a positive sweat test. Furtheron

I have copied the opinion of the CFF from their website below. The

last paragraph is important

The Ambry test comes 285$, what's the difference to another sweat

test? And the NPD and ERCP are made for those pwcf, who can't be dxed

through the sweat test.

Please don't give up! Even if your doc is right you need a certain dx

for the health of Dawn and the health of your mind.

Peace

Torsten

Eur J Pediatr 2002 Apr;161(4):212-5 Related Articles, Links

Negative sweat test in hypertrypsinaemic infants with cystic fibrosis

carrying rare CFTR mutations.

Padoan R, Bassotti A, Seia M, Corbetta C.

Cystic Fibrosis Centre, A O Istituti Clinici di Perfezionamento,

Milano, Italy. rita.padoan@...

Persistent hypertrypsinaemia in newborn screening for cystic fibrosis

(CF) recognises subjects at high risk to be affected. Diagnosis is

confirmed by a positive sweat test and/or by the presence of two

mutations in the cystic fibrosis transmembrane regulator gene. The

aim of the present study was to evaluate the occurrence of a negative

sweat test (chloride < 60 mmol/l) during the first months of life, in

hypertrypsinaemic infants, which would lead to a delayed diagnosis.

We reviewed clinical charts of CF patients born between January 1993

and September 1998, when the neonatal screening programme consisted

of an immunoreactive trypsinogen (IRT)/DNA (F508del) + IRT strategy.

Laboratory and clinical data were collected for patients diagnosed

after 12 months of life. Out of 446,492 newborns, 104 CF patients

were diagnosed giving an overall incidence of 1:4293. Of these, six

had a blood IRT level above the cut off value (99th percentile) and a

negative sweat test in the first trimester of life. At a mean age of

3.5years, the patients were again referred to our CF Centre for re-

evaluation in order to confirm or exclude the disorder. Molecular

analysis identified the following genotypes: F508del/A309D,

F508del/3849 + 10kbC-->T, F508del/R117H (in two patients), R117H/

L997F, and F508del/R117L. CONCLUSION: Infants with cystic fibrosis

bearing a spectrum of mild cystic fibrosis transmembrane regulator

gene mutations may present as hypertrypsinaemic newborns with a sweat

chloride within the normal range. Reference values for normal sweat

test during the first months of life should be revised. A wide

molecular genetic analysis is recommended for newborns presenting

persistent hypertrypsinaemia and a sweat test result > 30 mmol/l in

order to diagnose atypical forms of the disease.

PMID: 12014388 [PubMed - in process]

Chest 2000 Dec;118(6):1591-7 Related Articles, Links

Genotype analysis and phenotypic manifestations of children with

intermediate sweat chloride test results.

Desmarquest P, Feldmann D, Tamalat A, Boule M, Fauroux B, Tournier G,

Clement A.

Departements de Pneumologie Pediatrique-INSERM U515, Hopital

Trousseau AP-HP, Universite Paris VI, Paris, France.

STUDY OBJECTIVES: Cystic fibrosis (CF) is one of the most common

inherited diseases among whites. Since the cloning of the CF

transmembrane conductance regulator (CFTR) gene, a number of studies

have focused on associations between the genotype and phenotype in

CF. This had led to the progressive identification of new groups of

patients, including those who have mild lung disease and those who

have normal sweat chloride values (< 60 mEq/L). The aim of the

present work was to provide information on the genotype and the

phenotypic characteristics of children with intermediate-range sweat

chloride test results. PATIENTS AND RESULTS: We focused on children

referred to the pulmonary department for various types of pulmonary

disease and who had several sweat chloride test results with median

values in the range of 40 to 60 mEq/L. Twenty-four patients over a 10-

year period were enrolled (mean age, 4.8 years). Respiratory

manifestations at initial evaluation included recurrent bronchitis,

wheezing, chronic cough, and pneumonia. The duration of the follow-up

ranged from 0.5 to 10.5 years. Sputum cultures revealed the presence

of Haemophilus influenzae (10 children), Staphylococcus aureus (4

children), and Pseudomonas aeruginosa (3 children). Pancreatic

insufficiency was found in two patients. Analysis of the entire

coding sequence allowed identification of 16 known mutations in CFTR

gene. Fifteen chromosomes (31.2%) carried a mutation in CFTR gene and

one allele carried two mutations. Three patients were homozygous or

double heterozygous (DeltaF508/DeltaF508, DeltaF508/3849 + 10 kb C--

>T, S1235R/G551D). The 5-thymidine allele was identified in four

children. CONCLUSION: These results indicate an higher frequency of

CFTR gene mutations in patients with borderline sweat chloride test

results, compared to data reported in the general population. They

lead to the recommendations for complete pulmonary and GI

investigations in this group of patients, as well as assiduous care

and medical follow-up.

PMID: 11115444 [PubMed - indexed for MEDLINE]

Sweat Testing

Sweat Testing Procedure and Commonly Asked Questions

Overview

The sweat test has been the " gold standard " for diagnosing cystic

fibrosis (CF) for more than 40 years. When it is performed by trained

technicians, and evaluated in an experienced, reliable laboratory,

the sweat test is still the best test to diagnose CF. It is

recommended that the sweat test be performed in a Cystic Fibrosis

Foundation-accredited care center where strict guidelines are

followed to ensure the accuracy of the results. The test can be

performed on individuals of any age. However, some infants may not

make enough sweat for the laboratory to analyze. If an infant does

not produce enough sweat on the first sweat test, it should be

repeated to collect more.

What happens during a sweat test?

The sweat test determines the amount of chloride in the sweat. There

are no needles involved in the procedure. In the first part of the

test, a colorless, odorless chemical, known to cause sweating, is

applied to a small area on an arm or leg. An electrode is then

attached to the arm or leg, which allows the technician to apply a

weak electrical current to the area to stimulate sweating.

Individuals may feel a tingling sensation in the area, or a feeling

of warmth. This part of the procedure lasts approximately five

minutes. The second part of the test consists of cleaning the

stimulated area and collecting the sweat on a piece of filter paper

or gauze or in a plastic coil. Thirty minutes later, the collected

sweat is sent to a hospital laboratory for analysis. The entire

collection procedure takes approximately one hour.

What does the sweat test reveal?

Your physician has asked that this test be performed to rule out the

presence of CF, an inherited disorder of the lungs, intestines and

sweat glands. Children and adults with CF have an increased amount of

sodium and chloride (salt) in their sweat. In general, sweat chloride

concentrations less than mmol/L are normal (does not have CF); values

between 40 to 60 mmol/L are borderline, and sweat chloride

concentrations greater than 60 mmol/L are consistent with the

diagnosis of CF. For individuals who have CF, the sweat chloride test

will be positive from birth. Once a test result is positive, it is

always positive. Sweat test values do not change from positive to

negative or negative to positive as a person grows older. Sweat test

values also do not vary when individuals have colds or other

temporary illnesses.

Is there any preparation for the sweat test?

There are no restrictions on activity or diet or special preparations

before the test. However, one should not apply creams or lotions to

the skin 24 hours before the test. All regular medications may be

continued and will have no effect on the test results.

When are sweat test results made available?

Sweat test results are usually available to your physician on the

next working day after the test is performed. In a small number of

cases, the quantity of sweat obtained is not sufficient to give an

accurate result, and the test may need to be repeated.

Can the test results be inconclusive?

Yes. In a small number of cases, the test results fall

into " borderline " range between not having CF and indicative of CF.

In these situations, repeat sweat tests, as well as other diagnostic

procedures, may need to be carried out. These will only be done after

consultation with a physician.