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PubMed1979

[Discrepancies between TRH test and classical dynamic thyroid tests results in hyperthyroidism. 47 cases (author's transl)].

We have investigated the frequency of discordant results between the TRH test and classic dynamic tests of thyroid function (thyroid suppression and TSH stimulation tests) for patients presenting a diagnostic problem for hyperthyroidism. 12 patients in group I posed the problem of having a relapse of Graves' disease previously treated: a discrepancy between TRH and T3 suppression test results was observed in 17% of the cases. 10 patients in group II demonstrated the ophtalmopathy of Graves' disease without hyperthyroidism: discordance between tests results in this group was present for 20%. Finally, 25 patients in group III had a "hot" thyroid nodul apparent at thyroid scan: in 40% of the cases, the response to TRH did not lead to the same diagnosis that was suggested by the classical dynamic tests of thyroid regulation. The discrepancies observed in this work, between the results of the TRH test and those of classic dynamic tests, demonstrate that this two types of tests are not completely interchangeable, because they do not reflect exactly the same function.

Adult↗
PubMed1953

Measurement of thyroxin synthesis with I131; a test for evaluation of thyroid function in equivocal states.

As the function of the thyroid gland is the synthesis and secretion of thyroxin, a test which correctly measures this process is best for diagnosis of thyroid disorder and for determining the success of therapy. The rate of secretion can be measured with a Geiger counter which indicates what proportion of radioactive iodine in a serum specimen is in the form of thyroxin. The normal proportion is 2 to 10 per cent; in hyperthyroidism the proportion is 50 to 70 per cent, and in hypothyroidism less than 1 per cent. The same test has served to detect metastases of thyroid carcinoma following total thyroidectomy.

Humans↗
PubMed2003

[The effect of laryngectomy and postoperative radiotheraphy on thyroid gland functions].

OBJECTIVES: We investigated the frequency of hypothyroidism in patients treated with total laryngectomy, hemithyroidectomy-isthmectomy, and postoperative radiotherapy for T3 or T4 larynx cancers. PATIENTS AND METHODS: Twenty-nine male patients (mean age 54 years; range 43 to 72 years) with T3 or T4 larynx cancers were prospectively included in the study. Preoperatively, thyroid function tests were normal in all the patients. Following radiotherapy, serum thyroid-stimulating hormone (sTSH), free triiodothyronine (FT3), and free thyroxine (FT4) levels were measured every three months at least for a year. Detection of an increased level of sTSH together with decreased or normal levels of FT3 and/or FT4 indicated clinical and subclinical hypothyroidism, respectively. The relationship was assessed between hypothyroidism and both age and radiotherapy dosage. Statistical analyses were made with the use of the Student's t- test and Mann-Whitney U-test. RESULTS: Following radiotherapy, thyroid function tests remained normal in 12 patients (41%), while 12 patients (41%) and five patients (18%) developed subclinical and clinical hypothyroidism, respectively. No significant relationship was found between age and thyroid dysfunction (p>0.05), whereas radiotherapy dosage was found in significant relationship with the development of hypothyroidism (p<0.05). CONCLUSION: Due to high rates of subclinical or clinical hypothyroidism following combined therapy, thyroid functions should be closely monitored in patients undergoing laryngectomy for T3 or T4 larynx cancers.

Adult↗
PubMed1976

Evaluation of three thyroid-function screening tests for detecting neonatal hypothyroidism.

Three thyroid-function detection methods were evaluated concomitantly for possible application as routine screening tests for the early diagnosis of neonatal hypothyroidism. Dried capillary-blood thyroxine (T4) was measured on eluted filter-paper discs for 9734 3-5-day old neonates. Serum T4 and thyroid-stimulating hormone (T.S.H.) assays from cord blood were studied as alternative screening tests on 4911 and 3733 infants, respectively. To avoid false-negative results, neonatal blood-T4 and cord serum-T4 screening methods were followed up for the lower 10th and 6th percentile, respectively. This resulted in a false-positive recall incidence greater than 92% owing to various additional factors which also influence T4 levels: thyroxine-binding-globulin deficiency, prematurity, and maternal drug ingestion. In marked contrast, cord T.S.H. as an initial screening test had a higher specificity and sensitivity for the diagnosis of primary hypothyroidism with the two affected cases, having values greater than 70 muU/ml (with only 0-24% of the screened population having values greater than 50 muU/ml). In order to avoid the impracticably high recallrate and false-positive incidence resulting from an initial T4 screening test, and to reduce the estimated follow-up recall to less than 0-2% of the screened infant population, it is recommended that infants with low T4 be selected for a supplementary T.S.H. screening test.

Capillaries↗
PubMed1978

Correlation between per cent discharge of thiocyanate test and thyroid functions in patients with Hashimoto's disease.

The thiocyanate test was carried out in 18 patients with Hashimoto's disease. Thiocyanate was given orally several hours after the administration of tracer doses of 131I when the thyroid counts seemed to have reached a plateau. The per cent discharge of thiocyanate test was significantly higher in the groups with lower level of T4 (less than 5.5 microgram/100 ml), RSH (less than 25.5%) and BMR (less than +2.5%), and higher levels of TSH (greater than 10.0 muU/ml). A chi-square (chi2) test with Yates correction led to chi2 = 3.56 (1 df) with P = 0.06 (per cent discharge vs T4, RSU, BMR and TSH). Then the per cent thiocyanate discharge was increased with the degree of hypothyroidism in patients with Hashimoto's disease. The correlation between the per cent discharge and 131I 24 h uptake was not significant. It was apparent that the iodide concentration mechanism was present even in the severe hypothyroid stage of Hashimoto's disease. This disproportion between the uptake of iodide and the iodide organification may result in the increase in unbound iodide. It is concluded that the hypothyroidism in Hashimoto's disease may not be caused by a defect in iodide organification, even if it correlated to the degree of hypothyroidism.

Adult↗
PubMed2000

An identical neo-mutation in the thyroid hormone receptor beta gene (A317T) in 2 unrelated Thai families with resistance to thyroid hormone.

We reported two unrelated Thai girls with resistance to thyroid hormone. The affected patients presented with goiter and no other stigmata of hyperthyroidism. Their serum T4, T3, free T4 and free T3 concentrations were high and they had normal levels of TSH. The affected girl in family 1 was treated with an antithyroid drug for 1-9/12 years. The affected girl in family 2 was only observed her thyroid function tests. TRH test showed normal TSH response in both girls. Analysis of the thyroid hormone receptor beta gene of both affected girls revealed the same missense mutation, changing the guanine in nucleotide 1234 to an adenine which results in the replacement of the normal alanine (GCT) with a threonine (ACT) at codon 317. Two proposita were heterozygous, and this mutation was not present in their parents compatible with a neo-mutation.

Adolescent↗
PubMed1993

Goiter in adolescents.

Enlargement of the thyroid gland during adolescence should be considered a pathologic rather than physiologic process. With diffuse enlargement in an asymptomatic patient, thyroid function tests and thyroid antibodies usually are the only tests needed to define the diagnosis of euthyroid autoimmune thyroiditis. Patients with lobular or nodular thyroid enlargement may require additional tests if the diagnosis of Hashimoto's thyroiditis cannot be established by the presence of thyroid antibodies in serum. The tests to define the anatomic and functional status of nodular thyroid disease include ultrasonography and radionuclide scintigraphy of the thyroid, but rarely fine needle biopsy. The only indications for surgical therapy of the thyroid are hyperfunctioning thyroid adenomas, the suspicion of thyroid carcinoma and Graves' disease in patients who are not responsive to antithyroid drug therapy and who are poor candidates for radioiodine ablative therapy. The prognosis of thyroid disease during c adolescence is usually excellent.

Adolescent↗
PubMed1988

Thyroid test abnormalities in traumatic brain injury: correlation with neurologic impairment and sympathetic nervous system activation.

Acute illness is well known to affect thyroid function, but there are few studies correlating the severity of the underlying medical problem with indexes of thyroid function and little is known about its cause. Traumatically brain-injured patients were selected because they were a relatively homogeneous, previously healthy group with a condition whose severity was readily quantifiable. In 66 such patients, the relationships between changes in thyroid function tests (thyroxine, free thyroxine, triiodothyronine, reverse triiodothyronine, and thyrotropin levels), catecholamine and cortisol concentrations measured on admission and again four days after the accident, and neurologic function assessed by the Glasgow Coma Score (GCS) were studied. Triiodothyronine and thyroxine levels fell significantly within 24 hours of injury. Four days after the accident, patients with the greatest neurologic dysfunction had the lowest triiodothyronine and thyroxine levels; significant correlations were present between the Day 4 GCS and concomitant thyroxine (r = 0.47, p less than 0.0001), free thyroxine (r = 0.32, p less than 0.02), and triiodothyronine (r = 0.50, p less than 0.0001) levels. Reverse triiodothyronine values remained unchanged throughout the study even in the most severely affected patients; the rise in thyrotropin levels was not significant (1.2 +/- 0.2 to 1.7 +/- 0.3 microU/ml, p = NS). Patients who died or remained vegetative had thyroxine and triiodothyronine levels 30 percent to 50 percent lower than those who had a good recovery (p less than 0.05). Highly significant correlations were present between Day 4 thyroxine and triiodothyronine levels and admission and Day 4 norepinephrine and epinephrine concentrations. There was no association between admission or concomitant cortisol levels and thyroid function on Day 4; treatment with high-dose dexamethasone did not influence these indexes. Thus, patients with traumatic brain injury exhibit a gradient of thyroid dysfunction that occurs promptly, is dependent upon the degree of neurologic impairment, and reflects ultimate outcome. The significant association with catecholamine levels suggests a role for sympathetic nervous system activation in its causation, independent of a generalized stress response, since there is no correlation of thyroid test abnormality with the degree of adrenocortical secretion.

Adult↗
PubMed1999

Is it possible to diagnose canine hypothyroidism?

A definitive diagnosis of hypothyroidism can be difficult because of the many clinical abnormalities associated with thyroid hormone deficiency, and the lack of readily available diagnostic tests with high sensitivity and specificity. Thyroid function tests should be performed only in dogs with clinical findings consistent with hypothyroidism. Measurement of serum total thyroxine (T4) concentration is a useful initial screening test since most hypothyroid dogs have values below the reference range. Serum free T4 concentration measured by equilibrium dialysis is a more sensitive and specific test of thyroid function than total T4 and is particularly useful in dogs with non-thyroidal illness or atypical clinical signs. Measurement of serum endogenous thyroid-stimulating hormone concentration is also helpful, but many hypothyroid dogs have normal results. The gold standard for diagnosis of hypothyroidism remains the thyroid-stimulating hormone response test. It should be used to confirm hypothyroidism when other tests do not agree with the clinical impression or if atypical signs or non-thyroidal illness exist or there has been administration of drugs known to alter thyroid function tests. Ultimately, a positive response to treatment is expected in hypothyroid dogs treated appropriately with levothyroxine.

Animals↗
PubMed1984

A sensitive immunoradiometric assay for serum thyroid stimulating hormone: a replacement for the thyrotrophin releasing hormone test?

The value as a thyroid function test of a new, rapid, and highly sensitive immunoradiometric assay for thyroid stimulating hormone (TSH) was assessed in 188 consecutive new patients with suspected hyperthyroidism. The diagnosis was made on clinical grounds and on the basis of serum total triiodothyronine and thyroxine concentrations and the response of TSH to thyrotrophin releasing hormone (TRH) as measured by radioimmunoassay. In all except one patient the basal TSH concentration by immunoradiometric assay predicted the response of TSH by radioimmunoassay to TRH, an undetectable value being recorded in patients with a subnormal response and a measurable value in those with a normal test result. This clear relation was not observed for basal TSH concentrations as measured by radioimmunoassay. In a series of 39 hospital inpatients with acute or chronic non-thyroidal illness, of whom 11 had low concentrations of total thyroxine or triiodothyronine, or both, basal TSH concentrations were detectable by both radioimmunoassay and immunoradiometric assay in all cases and were associated with normal responses to TRH. The immunoradiometric assay for TSH, which is commercially available, may therefore obviate the need for the more time consuming TRH test and simplify the approach to thyroid function testing in patients with suspected hyperthyroidism.

Adult↗