PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Thyroid Function Tests”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1982

Cost-effectiveness of thyroid function tests.

The cost-effectiveness of thyroid function tests (serum thyroxine concentration, triiodothyronine [T3]-resin uptake, free thyroxine index, serum T3, and serum thyrotropin concentration) was assessed in 135 ambulatory patients suspected of hypothyroidism or hyperthyroidism who did not have a history of thyroid disease requiring medication or thyroid surgery within the preceding two years. Of patients with five or more signs and symptoms compatible with thyroid dysfunction, 50.0% had biochemical abnormalities substantiating hypothyroidism or hyperthyroidism, while only 1.5% of patients with fewer than two signs and symptoms had either disease. The cost of thyroid function tests was twice as much per patient evaluated by residents as for those evaluated by faculty physicians. These results suggest that interventions to reduce the number and type of tests in patients without multiple signs and symptoms of thyroid disease could improve the cost-effective use of these tests.

Cost-Benefit Analysis↗
PubMedDate not supplied

[Thyroid function tests in healthy and ill elderly].

Thyroid function in the elderly has been a matter of discussion. The universe of the present study includes males and females 36 hospitalized with an average age of 72.97 +/- 8.70 years (group I) and 36 ambulatory asymptomatic elderly with 69.81 +/- 8.55 years of age (group II). Serum levels of T3, T4, T4L and TSH were measured in both groups. Mean values of T3 were significantly lower in the hospitalized patients than in the control group. The difference persisted on both, males and females, analyzed separately. Mean values of T4L were significantly lower in women of group II, while mean values of T3 were significantly lower in men of group I. The comparison of thyroid function tests in male and female showed that serum values of T3 and T4 were significantly lower in men of group I. By dividing results in age categories, serum levels of T4L in group II were significantly lower in the age group of 70 to 79 and 80 to 89. Thyroid function tests in asymptomatic ambulatory elderly tend to be normal, whereas the hospitalized patients showed a high proportion of alterations.

Aged↗
PubMed1986

Evaluation of strategy for testing thyroid function applied to hypothyroidism.

A strategy for testing thyroid function with discretionary assay of thyroid stimulating hormone (TSH) following initial measurement of total plasma thyroxine (tT4) was retrospectively evaluated in relation to the diagnosis of primary hypothyroidism. Over a two year period 14 641 tT4 assays were done and 6887 TSH assays, of which 29% were initiated in the laboratory. The percentage of raised TSH values (over 5 mU/1) was similar to those for clinician and pathologist initiated requests (23.2% and 23.6%). Some TSH requests (1620) were cancelled; when 212 of these were subsequently analysed the TSH value was raised in 5.7% The incidence of raised TSH values in 188 patients with a tT4 below 100 nmol/1 (7.8 micrograms/100 ml), in whom TSH was not requested, was 5.3% Most of these raised TSH results could be readily explained by information available to the requesting clinician but not given on the request form.

Adult↗
PubMed1976

A rational approach to "in vitro" thyroid function testing.

A system of "in vitro" thyroid function testing is proposed whereby laboratory staff select the most appropriate screening test depending on the information supplied by the clinician. Total serum triiodothyronine (T3) or thyroxine (T4) are used for screening as appropriate. In borderline cases, secondary tests are performed automatically according to a flow chart. This system improves efficiency and is cost effective, saving approximately 1,800 pounds annually in a laboratory handling about 5,000 requests for thyroid function tests each year.

Aged↗
PubMed1992

[Thyroid function tests in acute drug intoxication].

It is well known that thyroid function tests may be changed in non-thyroidal illnesses. To understand the influence of acute drug intoxication on thyroid function tests, 31 drug intoxicated patients without previous thyroid disorders and systemic diseases were included in our study. T3, T4, TSH, and resin T3 uptake were checked as soon as they arrived at our emergency service and were compared to that of 58 healthy volunteers. Within 31 patients, 14 were intoxicated by organophosphorous compounds, 6 by sedatives and hypnotics, 3 by strong acid, 2 by paraquet, 2 by rodenticides (warfarin), 2 by lysol and the other 2 were intoxicated by acetaminophen. The mean T3 and TSH levels were significantly lower in the drug intoxicated group. Among the 31 patients, 14 (45.2%) had a low T3, 2 (6.5%) had a low T3 and T4, and 6 (19.3%) had an elevated T4. All of the patients with an elevated T4 were intoxicated by organophosphates. If we divided the 31 patients into 2 subgroups: organophosphate intoxicated group and non-organophosphate intoxicated group, T4 and FT4I were significantly higher in the former group. Thyroid function tests became normal after treatment in 27 patients, discharged in good general condition. T3 and T4 became extremely low in 4 patients before they expired. The present study confirms that acute drug intoxication, like other non-thyroidal illnesses, affects thyroid function tests. Acute organophosphate intoxication may cause transient hyperthyroxinemia.

Acute Disease↗
PubMed2001

[Thyroid function tests].

About 80% of thyroid disease consists of thyroid-specific autoimmune diseases, Hashimoto's disease and Grave's disease. To diagnose thyroid diseases, testings for (1) thyroid function and (2) pathogenetic autoantibodies are indispensable. To assess thyroid function, serum hormone concentrations, such as TSH, FT4 and FT3 are measured. Among these hormones, serum TSH concentrations are the most reliable and informative regarding thyroid function, correcting indicating a hyperthyroid, euthyroid or hypothyroid state. Therefore, TSH measurement appears to be the first choice in selecting the hormone determination. Reference intervals for normal healthy subjects of TSH are around 0.4-5.0 microU/ml. The second choice for thyroid function assessment are FT4 which supersedes total T4(TT4). TT4 is affected by changes in serum thyroid hormone binding proteins(TBG, TTR, Albumin). For example, euthyroid pregnant women whose serum TBG are physiologically higher than those of non-pregnant women show augmentation of TT4. However, FT4 depicts within reference intervals, although measurement of FT4 alone is unable to detect any abnormality of thyroid hormone binding proteins. According to its plasma concentration and binding affinity, FT3 measurement deserves no more significance than T3. Another important test for thyroid diseases is to detect serum autoantibodies against thyroid tissues, such as TgAb, TPOAb. Much more important is TSH receptor antibody which differentiates Graves' disease from Hashimoto's thyroiditis. In patients who show hyperthyroidism and some very uncommon hypothyroidism, TSH receptor antibodies should be measured. Three indicators are available as routine tests; TRAb measured by radioreceptor assay; TSAb determined by bioassay using cultured porcine thyroid cells. Usually, TRAb activity clinically correlates well with TSAb. TSBAb was initially discovered in patients with severe hypothyroidism with atrophic thyroid gland. TSBAb blocks thyroid stimulating activity of TSH and consequently causes severe hypothyroidism. TRAb and TSAb are very useful to diagnose and follow patients with Grave's disease.

Graves Disease↗
PubMed1978

[Sex hormone binding globulin (SHBG), a new metabolic in vitro thyroid function test].

SHBG (sex hormone binding globulin) is a carrier protein for the sex hormones testosterone and estradiol with a molecular weight of about 95000 dalton. It can be used as a metabolic test of thyroid function. SHBG was measured by the adsorption method of Mickelson and Petra; the SHBG contained in serum is incubated with 3H-5alpha-dihydrotestosterone and adsorbed to a cellulose filter. Thirty-eight female patients with hyperthyroidism before treatment had markedly elevated levels of SHBG (x +/- SD: 4.85 +/- 2.4 microgram DHT/100 ml) compared with normal controls (1.50 +/- 0.57; p is less than 0.001). A good correlation between the thyroid hormones and SHBG could be domonstrated which was better for T3 than for T4:r =0.76 (p is less than 0.001) for T3 and r= 0.65 (p is less than 0.001) for T4. This agrees with the clinical finding that the circulating T3 level is a better index of the metabolic severity of thyrotoxicosis than T4. After radioiodine treatment SHBG returns to normal values in euthyroid patients (1.38 +/- 0.8; n = 15) and remains elevated in persistent hyperthyroidism (3.99 +/-1,6; n = 67). Even in patients with persistent biochemical hyperthyroidism who are completely euthyroid on clinical examination, SHBG remains high. Despite lack of evidence of clinical hyperthyroidism, this metabolic test demonstrates the biologic significance of merely biochemical hyperthyroidism. Estimation of SHBG as a metabolic thyroid function test in vitro is of special value for the evaluation of patients showing discrepancies between the clinical and biochemical states and for borderline hyperthyroidism.

Carrier Proteins↗
PubMed1985

Abnormalities of thyroid function tests in hospital inpatients.

Results of thyroid function tests were analysed in 199 clinically euthyroid inpatients with normal serum thyroid stimulating hormone values. Serum total triiodothyronine was less than 1.25 nmol/l in 61.8% of samples, free triiodothyronine less than 3.9 pmol/l in 57.8%, total thyroxine less than 63 nmol/l in 21.1% and free thyroxine less than 9.5 pmol/l in 17.6%. In contrast, thyroxine binding globulin ratio was below normal (less than 5) in only 5 samples. A significant positive correlation (P less than 0.001) of serum free thyroxine with total thyroxine, thyroxine/thyroxine binding globulin ratio and free triiodothyronine was present as well as a significant negative correlation (P less than 0.001) with serum thyroid stimulating hormone. There was no correlation of free thyroxine measurements with serum albumin or non-esterified fatty acid concentrations. Although serum free thyroxine is low in a number of patients with non-thyroidal illnesses, this does not appear to be due to a rise in non-esterified fatty acids or a fall in albumin as has been proposed. Serum thyroid stimulating hormone measurements are essential to confirm the diagnosis of hypothyroidism in such subjects.

Humans↗
PubMed1994

Prevalence of abnormal thyroid function tests in connective tissue disease.

The prevalence of thyroid function tests' abnormalities in 170 patients with various connective tissue diseases (CTD) was examined and compared to a group of 100 age- and sex-matched controls. The overall prevalence of diagnosed thyroid disease was 3.5%. Categorizing the patients into 5 "functional groups" by the concurrent thyroid function test/results showed normal thyroid function tests in 14%, isolated elevated TSH levels with normal T4 and T3 levels in 4% and findings consistent with the laboratory diagnosis of primary hypothyroidism in 3%. The "euthyroid sick syndrome" was evidenced in 54% and elevated T4 levels and/or increased or normal T3 values with normal TSH in 25%. Antimicrosomal antibodies were noted in 12 patients (7%), with the highest incidence in systemic lupus erythromatosus patients (10%). patients with mixed connective tissue disease had significantly (p < 0.0005) higher frequency of hypothyroidism, whereas patients with systemic vasculities had higher frequency of hyperthyroxinemia. In conclusion, CTD patients frequently have abnormal results of one or more of thyroid function tests. Hypothyroidism and hyperthyroidism should be considered when evaluating symptoms and signs in CTD and a significant subset of CTD patients appears to be predisposed to the development of hyperthyroidism.

Adolescent↗
PubMedDate not supplied

Minor alterations in thyroid-function tests associated with diabetes mellitus and obesity in outpatients without known thyroid illness.

Thyroid function tests might be affected by diabetes and obesity. To evaluate the influence of these parameters in routine conditions, 72 diabetic and 53 non-diabetic outpatients without known thyroid diseases or severe chronic illness were recruited over a 7-month period. For each patient, dosages of thyrotropin (TSH), total and free thyroxine (TT4 and FT4, respectively), total and free triiodothyronine (TT3 and FT3) and T3 resin uptake (T3RU) were performed by radioimmunoassays. The simultaneous influence of various parameters known to affect thyroid-function tests was evaluated by multivariate linear regression. The studied variables included gender, age, glucosteroids, estrogens, tobacco habits, iodine contacts, body mass index (BMI) and diabetes mellitus. Tobacco habits and iodine contacts did not influence any tests. As expected, estrogens induced an increase in TT4 and TT3 values (p < 0.001 and 0.020, respectively) associated with a decrease in T3RU (p < 0.001). Consequently, females had lower T3RU than males (p < 0.0001). Corticotherapy was associated with decreased TSH values (p = 0.022). TT3 and FT3 decreased with age (p < 0.001), whereas T3RU and FT4 increased (p = 0.020 and 0.004, respectively). In contrast to an increase in TSH (p = 0.006), TT4 and FT4 decreased at higher BMI levels (p = 0.018 and 0.004, respectively), which is consistent with subclinical hypothyroidism. In diabetic patients, TSH was lower than in nondiabetic subjects (p = 0.039). Thus, the present study indicates that besides known parameters such as age and drugs, thyroid-function tests can also be altered by diabetes mellitus and obesity.

Adolescent↗
PubMedDate not supplied

The variations in thyroid function tests compatible with clinical euthyroidism after medical and surgical treatment for Graves' disease.

Eight widely used tests of thyroid function (clinical and biochemical) were performed simultaneously on 46 thyrotoxicosis patients who were clinically well at a standardised interval after medical or surgical treatment. The aim was to establish the range of thyroid function compatible with clinical normality. While clinical scoring systems gave broadly similar results between surgically and medically-treated patients, thyroid biochemistry showed major differences. Thus while 87% of medically-treated and 74% of surgically-treated patients were classified clinically euthyroid by the clinical indices devised by Crooks and Billewicz, the TRH test was exaggerated in 77% of the latter group but in only 13% of the former. On the other hand, half of the 26% of surgical patients with a clinical index suggesting hyperthyroidism had normal thyroid hormone levels and exaggerated TRH tests. No patient was categorised as clinically hypothyroid despite basal TSH levels as high as 21 mU/L (N : less than 5 mU/L) and T4 levels as low as 42 nmol/L (N: 70.150 nmol/L). Substitution of FT4 index for total T4 did not significantly alter the classification or ranking of patients in either treatment group. The early (20-minute) 132I uptake was normal in all but one case. We conclude that abnormal laboratory tests of thyroid function are found frequently after treatment in thyrotoxicosis patients with few or no clinical features of thyroid disturbance.

Graves Disease↗
PubMed1993

Automation of thyroid function testing.

This article discusses the automation of thyroid function testing. The needs for automation are included in the introduction. The issues concerning automation of immunoassay are discussed, including homogeneous or heterogeneous immunoassay, competitive or immunometric assay, reagent stability, data management, sample management, signal detection, and the disadvantages of automation. Individual immunoassay systems are summarized with a table outlining the key features. Both technical and clinical performance of automated thyroid function testing are described. The article ends with a discussion of the future trends of automated immunoassay testing.

Autoanalysis↗
PubMed2004

A more appropriate algorithm of thyroid function test in diagnosis of hyperthyroidism for Thai patients.

BACKGROUND: Thyroid function test is an essential tool in the diagnosis of thyroid dysfunction. To date, it is still controversial which diagnostic algorithm is best applicable to clinically hyperthyroidism patients. OBJECTIVE: To compare various algorithms of thyroid function tests in the diagnosis of hyperthyroidism. METHOD: Patients from the endocrine clinic, King Chulalongkorn Memorial Hospital were investigated for thyroid function tests (T3, T4, FT3, FT4 and TSH). Hyperthyroidism was defined as an elevated either FT3 or FT4 with suppressed TSH. The authors compared the effectiveness in hyperthyroidism diagnosis among algorithms by using sensitivity, specificity, positive predictive value and negative predictive value. RESULTS: Of all 452 patients in the present study, 94.24 percent were women. There were 206 hyperthyroidism, 30 subclinical hyperthyroidism, 1 subclinical hypothyroidism, 8 primary hypothyroidism and 207 normal subjects. The incidence of T3 toxicosis was 16.02% while that of T4 toxicosis was 2.16%. After the effectiveness analysis of these algorithms, FT3 and TSH is the most optimal test with 97.57% sensitivity and 100% specificity. Compared to FT4 and TSH, it gave 83.98% sensitivity and 100% specificity. CONCLUSION: According to the high incidence of T3 toxicosis in the present study, FT3 and TSH should be the initial test for diagnosis of hyperthyroid patients in an outpatient setting and FT4 should be measured subsequently in case of suspected T4 toxicosis.

Adult↗
PubMed2003

Influence of acetylsalicylic acid and ketoprofen on canine thyroid function tests.

Many factors including drugs can influence thyroid function in humans, rats and dogs. Studies in humans report significant effects of non-steroidal anti-inflammatory agents (NSAIDs) on thyroid function tests, which can lead to misinterpretation of the results and inappropriate therapeutic decisions. As NSAIDs are used more and more frequently in dogs, it is important to know to what extent they can influence results. Eighteen spayed female beagle dogs were randomly assigned to three treatment sequences in a 3 x 3 crossover study design with treatments consisting of acetylsalicylic acid (ASA) (25 mg/kg BW q 12 h), ketoprofen (Keto) (1 mg/kg BW q 24 h) or placebo administered for a 1-week period with a 3-week washout period between treatment periods. Blood samples for determination of total thyroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3), thyrotropin (TSH), reverse triiodothyronine (rT3), Keto and ASA concentrations were taken during each treatment period on days 0, 1, 3 and 7. During the washout period samples were taken weekly. A significant decrease in TT4 was observed as soon as 24 h after ASA administration, whereas the decrease in TT3 was less pronounced and differed significantly from the placebo only after 1 week of administration. No significant effects were found for free T4 and TSH with ASA administration. No significant effects on thyroid results were found following Keto administration. The results indicate that TT4 can be markedly decreased by ASA therapy and until the results of further studies are available, thyroid function test results should be interpreted cautiously in dogs on NSAIDs therapy.

Animals↗
PubMed1987

Pitfalls in the interpretation of thyroid function tests in old age and non-thyroidal illness.

In hyperthyroidism, measurement of the serum thyroxine (T4) index or free concentration often suffices to establish the diagnosis. In hyperthyroidism, including 3,3',5-triiodothyronine (T3) toxicosis, thyrotrophin (TSH) response to thyrotrophin-releasing hormone (TRH) is blunted. Sensitive measurement of serum TSH may in the future be the first-line screening test not only for primary hypothyroidism but also for hyperthyroidism. In non-thyroidal illness serum T4, reverse T3 and T3 levels change in relation to severity of disease. In mild disease, T4 is initially increases as the severity of the non-thyroidal illness increases. Reverse T3 increases and serum T3 decreases when the patients become more ill. Serum TSH response to TRH is often blunted. In old age similar changes in serum iodothyronine concentrations may take place, probably related to existing non-thyroidal illness. Also many drugs may have different effects on serum parameters of thyroid function. In acute psychiatric diseases increased serum total and free T4 levels and a blunted TRH test may be encountered.

Aged↗
PubMed1997

Maternal thyroid function: interpretation of thyroid function tests in pregnancy.

Thyroid status is frequently assessed during pregnancy, both to evaluate suspected thyroid abnormalities, and to monitor the status, of pre-existing thyroid disease. However, the production, circulation, and disposal of thyroid hormone are all altered in pregnancy. Interpretation of thyroid function studies in the pregnant patient must be performed based on an understanding of the normal physiologic changes at each stage of pregnancy. Examples of pregnancy-associated changes include, estrogen-stimulated increase in serum thyroxine binding globulin, chorionic gonadotropin stimulated T4 and T3 production from the thyroid gland, and accelerated degradation of thyroid hormone by the placenta. The serum-TSH alone is usually not adequate to assess thyroid status in pregnancy, and the various conditions that can effect this measurement are described. The pattern of thyroid studies in pregnancy is important in diagnosing thyroid disease, and it may indicate physiologic adaptations to optimize maternal thyroid status for fetal development.

Female↗
PubMed1995

[Study of relationship between TCM syndrome-types of malignant tumours and thyroid functional test].

The relationship between the thyroid functional test in 107 malignant tumour patients' sera with Deficiency-Excessiveness Syndromes in TCM, was studied. The results revealed that there were significant differences between the FT3, FT4 in tumour and control groups (P < 0.01) as well as between the rT3, FT3/rT3 in each type of tumour and control groups (P < 0.05-0.01). There was also definite relationship between the FT3, rT3, FT3/rT3 and the degree of differentiation, rate of progression and malignancy of tumours as well. rT3 elevated and FT3 reduced in accordance with the lowering of body resistance and reinforcing of pathogenic factors. FT3, rT3, FT3/rT3 are essential factors that reflecting the wax and wane of body resistance in the cases with malignant tumours in modern medicine.

Adult↗