Diagnosis Of Thyroid Function Research Articles

ASSESSING THYROID FUNCTION: A REVIEW OF BIOCHEMICAL MARKERS AND TESTING STRATEGIES

The present work provides an in depth look at the biochemical markers and the testing strategies employed in appraising thyroid function. It involves the primary thyroid hormones such as TSH, T3, and T4 that are responsible for thyroid homeostasis and diagnosis of the dysfunction of the thyroid. The assessment also covers and evaluates the different testing methods and approaches to examine thyroid function which include immunoassays and mass spectrometry. The review offers the summary of advantages and disadvantages of different testing methods to increase the knowledge and to facilitate decision making regarding the diagnosis of thyroid function, and to improve the quality of care of thyroid-related conditions.

Фізіологічні зміни функції щитоподібної залози під час вагітності

Проаналізовано дані літератури щодо зміни функції щитоподібної залози під час вагітності. Описано низку чинників (підвищення рівня хоріонічного гонадотропіну людини, естрогенів, зміна процесів дейодування, потреби в йоді та ін.), що впливають на синтез вільних і зв’язаних фракцій тиреоїдних гормонів. Вказані характерні відмінності зазначених даних у різні триместри вагітності. Показано, що в багатьох вагітних рівень гормонів щитоподібної залози може виходити за межі нормальних значень. За даними літератури, у 9,7–30 % жінок рівень тиреотропного гормона не відповідає встановленим триместр-специфічним інтервалам. Напружена робота щитоподібної залози в матері підвищує ризик розвитку в ній патологічних змін, а порушення її функції становить ризик захворювань щитоподібної залози й у плода. З урахуванням вищевикладеного важлива своєчасна діагностика функції щитоподібної залози, контроль активності адаптивно-пристосувальних процесів гіпофізарно-тиреоїдної системи у вагітних жінок.

Analysis on the Application of Five-item Determination of Thyroid Function in Diagnosis of Thyroid Function

Analysis on the Application of Five-item Determination of Thyroid Function in Diagnosis of Thyroid Function

Measurement of Total Rather Than Free Thyroxine in Pregnancy: The Diagnostic Implications

In light of several recent recommendations to use total thyroxine (T4) measurements in the diagnosis of thyroid function in pregnancy (in particular, "Clinical Practice Guidelines for Hypothyroidism in Adults," cosponsored by the American Thyroid Association and the American Association of Clinical Endocrinologists, which promote the use of T4 over free T4 [FT4 ]), we have examined the implications of employing T4 for diagnostic discrimination in both pregnant and nonpregnant patient panels. Use of T4 assays has significant drawbacks in this regard, and we believe that the suggestion is a retrograde step in thyroid function testing. Analysis of the interplay between the concentrations of T4 and thyroxine-binding globulin (TBG), typifying their respective reference ranges in either the nonpregnant or pregnant euthyroid state, shows that the effective T4 range is widened significantly by the accompanying hidden variation in TBG levels. Accordingly FT4 assays that fully compensate for serum T4-binding protein concentrations should discriminate dysfunctionality from normality more efficiently than total hormone measurements, whether in pregnant or nonpregnant states. The euthyroid FT4 reference ranges typical of late pregnancy should also be more compact than those for the total hormone, because of the increased dominance of higher, though equivalently variable TBG concentrations on T4 levels. Parallel effects on T4 from similarly variable, though lower concentrations of TBG are indicated in the nonpregnant group. While acknowledging the difficulties in FT4 measurement arising from inconsistent calibration of present-day commercial assays, this finding questions the recommendation that total hormone assays should supersede the former in pregnancy.

Value of the free triiodothyronine index in the diagnosis of hyperthyroidism.

Normalized T4 (T4N), total T3, T3 resin sponge uptake (T3U) and the response of TSH to TRH were determined in 264 patients sent for diagnosis of thyroid function. Many of these patients were diagnostic problem cases. Those with disease or medication known to invalidate the TRH test, but not those with abnormal thyroid hormone binding capacity in serum, were excluded. A free T3 index (FT3 index) was calculated as the product of total T3 and T3U. The FT3 index tended to decline with increasing age, the mean value being significantly higher in the youngest patients (12-20-years-old) than in the older age groups. In the diagnosis of hyperthyroidism, the FT3 index was superior not only to T4N but also to total T3, particularly in the presence of elevated hormone binding capacity (relatively low T3U). It is anticipated that the FT3 index will be most useful as a routine test for hyperthyroidism, especially in several (though not all) instances where the TRH test is invalidated.

An evaluation of absorbent granule kits for determining serum thyroxine concentration and free thyroxine index in the diagnosis of thyroid function.

An evaluation of absorbent granule kits for determining serum thyroxine concentration and free thyroxine index in the diagnosis of thyroid function.

Computer diagnosis from tests of thyroid function.

ABSTRACT A digital computer program has been written to derive the most probable diagnosis of thyroid function, based only on the numerical results of technical tests. Test results are assumed to be distributed normally or lognormally. This program supplements, but does not duplicate, methods described by other workers who have based the diagnosis on the presence or absence of clinical signs and symptoms and upon “yes/no” rather than continuously distributed test results. The computations give full weight to tests of independent types, but those of a similar nature (expected to be highly correlated) are combined and considered as one test for processing. Input may be processed or unprocessed observations; if unprocessed, a test report is printed out as well as the diagnostic report. Separate diagnostic reports are produced for groups of tests that are spaced more than 6 weeks apart, and account is taken of the effects of prior medication, thyroidectomy or 131I therapy.

THE BINDING OF 131-I-TRIIODOTHYRONINE BY SERUM PROTEINS AS AN IN VITRO TEST OF THYROID FUNCTION.

ABSTRACT The efficiency of Sephadex column chromatography for the separation of free iodide, free T3, and protein bound T3 has been demonstrated. Protein bound T3 and free iodide appear as two well defined peaks of activity in the eluate, while free T3 remains bound to the Sephadex column. This methods makes the direct study of the binding of T3 to serum proteins possible and allows of correction for the free radioactive iodide present as a contaminant. The value of this method in 147 selected patients was demonstrated by the high degree of accuracy in the diagnosis of thyroid function. The clinical diagnosis was confirmed by this method in 141 patients (95.9%) and the test failed in 6 cases (4.1%). The use of this method as a clinical screening test of thyroid function is suggested as it is sufficiently reliable, simple to perform and does not expose the patient to radiation hazards.

Conditional Probability Program for Diagnosis of Thyroid Function

The frequencies of occurrence of certain clinical findings (signs, symptoms, and laboratory data) were determined in 879 patients who had been classified as hypothyroid, euthyroid, or hyperthyroid on the basis of their responses to therapy during at least 6 mo of observation. A Bayesian conditional probability model was employed to estimate the probability of each of these three conditions for each possible combination of clinical findings. When the study was limited to 268 cases in which the data were considered reasonably complete, the computer program gave the correct classification (ie, successfully predicted the therapeutic result) in 258 (96%). This degree of accuracy approached the level of agreement to be expected between an expert consultant and a well-qualified diagnosing physician.