scholarly journals Challenges in interpretation of thyroid hormone test results

2016 ◽  
Vol 144 (3-4) ◽  
pp. 200-203
Author(s):  
Tijana Lalic ◽  
Biljana Beleslin ◽  
Slavica Savic ◽  
Mirjana Stojkovic ◽  
Jasmina Ciric ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Thyroid Function ◽  
Genetic Disorder ◽  
Clinical Status ◽  
Nodular Goiter ◽  
Thyroid Function Tests ◽  
Thyroid Status ◽  
First Case ◽  
Secondary Hypothyroidism

Introduction. In interpreting thyroid hormones results it is preferable to think of interference and changes in concentration of their carrier proteins. Outline of Cases. We present two patients with discrepancy between the results of thyroid function tests and clinical status. The first case presents a 62-year-old patient with a nodular goiter and Hashimoto thyroiditis. Thyroid function test showed low thyroid-stimulating hormone (TSH) and normal to low fT4. By determining thyroid status (?SH, T4, fT4, T3, fT3) in two laboratories, basal and after dilution, as well as thyroxine-binding globulin (TBG), it was concluded that the thyroid hormone levels were normal. The results were influenced by heterophile antibodies leading to a false lower TSH level and suspected secondary hypothyroidism. The second case, a 40-year-old patient, was examined and followed because of the variable size thyroid nodule and initially borderline elevated TSH, after which thyroid status showed low level of total thyroid hormones and normal TSH. Based on additional analysis it was concluded that low T4 and T3 were a result of low TBG. It is a hereditary genetic disorder with no clinical significance. Conclusion. Erroneous diagnosis of thyroid disorders and potentially harmful treatment could be avoided by proving the interference or TBG deficiency whenever there is a discrepancy between the thyroid function results and the clinical picture.

Thyroid Function Tests in Thyroxine-Binding Globulin Deficiency

1979 ◽  
Vol 16 (1-6) ◽  
pp. 313-314 ◽  
Author(s):  
C. F. Cusick
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Function ◽  
Reference Range ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Thyroid Status ◽  
Thyroxine Binding Globulin ◽  
Serum Thyroxine ◽  
Function Tests ◽  
Lowered Serum

Results are presented on two patients with complete and two with partial thyroxinebinding globulin (TBG) deficiency. All four subjects had lowered serum thyroxine but were clinically euthyroid. While thyroid hormone uptake tests or TBG assay were effective in the recognition of such individuals, indices based on these tests were misleading in assessing their thyroid status. Results within the reference range were obtained with the Immophase Free Thyroxine assay.

scholarly journals MON-481 Remarkable Euthyroid Hyperthyroxinemia Mistaken for Thyrotoxicosis

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Annavi Baghel ◽  
Joshua D Maier
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Function ◽  
Clinical Status ◽  
Thyroid Function Tests ◽  
Thyroid Disorder ◽  
Diagnostic Challenge ◽  
Free T4 ◽  
Free T3 ◽  
History Of ◽  
Euthyroid Hyperthyroxinemia

Abstract CLINICAL CASE A 46 year old caucasian female with past medical history of menorrhagia was referred from primary care for evaluation of thyrotoxicosis. Thyroid function was assessed in the context of menometrorrhagia. She did not have any history of thyroid disorder or abnormal thyroid function tests. Per outside records, recent labs demonstrated TSH 0.88 uIU/mL (0.36-3.74), Free T4 > 8.00 ng/dL (0.76-1.46), Free T3 2.9 pg/mL (2.18-3.98). All other labs were within normal limits. Thyroid ultrasound revealed normal parenchyma and volume. She did not take any medications or supplements including biotin. She denied heat intolerance, anxiety, palpitations, dyspnea, tremors, hyperdefecation, or change in hair, skin, or mood. No epiphora, diplopia, or eye irritation was reported. Her father had been diagnosed with hyperthyroidism, mother with hypothyroidism. Repeat labs at our visit revealed normal TSH of 1.05 uIU/mL (0.358- 3.74), normal Free T3 2.58 pg/mL (2.18- 3.98), normal Total T3 136 ng/dL (80-200), elevated Free T4 >8.00 ng/dL (0.76-1.46) and elevated Total T4 11.6 ug/dL (4.5-10.5). These lab values were not consistent with patient’s euthyroid clinical status, prompting assessment of Free T4 by dialysis, normal at 1.5 ng/dL (0.9-2.2) and T3 uptake, high at 40% (24-39%). This picture was consistent with Familial Dysalbuminemic Hyperthyroxenemia (FDH). The decision was made not to treat the patient with anti-thyroid medications and to perform a confirmatory genetic testing to test for mutations in the ALB (albumin) gene. DISCUSSION The free T4 assay used by our institution is performed on the Siemens Dimension Vista platform using a two-step chemiluminescent immunoassay. While in theory two-step assays should not yield abnormal results in FDH, several two-step assays are known to yield falsely high results in patients with FDH (1, 2, 3). Other potential etiologies for discordant Free T4 levels include thyroid hormone autoantibodies, heterophile antibodies, biotin use, and anti-streptavidin antibodies (3). CONCLUSION Recognition of laboratory error in the workup of thyroid disease is essential. Clinicians must ensure thyroid function labs are consistent with each other and with the patient’s presentation. In such cases misdiagnosis of hyperthyroidism or thyroid hormone resistance may lead to unnecessary testing and inappropriate treatment (3). References 1. Cartwright D et al. Familial dysalbuminemic hyperthyroxinemia: a persistent diagnostic challenge. Clin Chem. 2009 May;55(5):1044-6 2. Ross HA et al. Spuriously high free thyroxine values in familial dysalbuminemic hyperthyroxinemia. Clin Chem. 2011 Mar;57(3):524-5 3. Favresse J et al. Interferences With Thyroid Function Immunoassays: Clinical Implications and Detection Algorithm. Endocr Rev. 2018 Oct 1;39(5):830-850.

scholarly journals DIAGNOSTIC DILEMMA IN DISCORDANT THYROID FUNCTION TESTS DUE TO THYROID HORMONE AUTOANTIBODIES

2017 ◽  
Vol 3 (1) ◽  
pp. e22-e25 ◽  
Author(s):  
Panudda Srichomkwun ◽  
Neal H. Scherberg ◽  
Jasminka Jakšić ◽  
Samuel Refetoff
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Function ◽  
Thyroid Function Tests ◽  
Diagnostic Dilemma ◽  
Thyroid Hormone Autoantibodies ◽  
Function Tests

EFFECT OF THYROID STATUS ON THE THYROTROPHIN-RELEASING HORMONE-DEGRADING ACTIVITY OF RAT SERUM

1976 ◽  
Vol 71 (1) ◽  
pp. 13-19 ◽  
Author(s):  
N. WHITE ◽  
S. L. JEFFCOATE ◽  
E. C. GRIFFITHS ◽  
K. C. HOOPER
Keyword(s):  
Thyroid Hormone ◽  
Human Serum ◽  
Thyroid Function ◽  
Thyroid Status ◽  
Rat Serum ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Tsh Levels

SUMMARY The TRH-degrading activity of rat serum in vitro is five times more potent than that of human serum. In rats, it is significantly reduced in hypothyroidism (thiouracil-induced) and significantly increased in hyperthyroidism (T3 or T4-induced). This suggests a possible role in the regulation of adenohypophysial-thyroid function which is probably, in turn, dependent on thyroid hormone, rather than TSH, levels.

Iodide Metabolism and Effects

2020 ◽  
pp. 25-33
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Thyroid Hormones ◽  
Dietary Supplement ◽  
Thyroid Function ◽  
Thyroid Stimulating Hormone ◽  
Hormone Synthesis ◽  
Serum Tsh ◽  
Tsh Stimulation ◽  
Sensitive Marker

Iodine (I2) is essential in the synthesis of thyroid hormones T4 and T3 and functioning of the thyroid gland. Both T3 and T4 are metabolically active, but T3 is four times more potent than T4. Our body contains 20-30 mg of I2, which is mainly stored in the thyroid gland. Iodine is naturally present in some foods, added to others, and available as a dietary supplement. Serum thyroid stimulating hormone (TSH) level is a sensitive marker of thyroid function. Serum TSH is increased in hypothyroidism as in Hashimoto's thyroiditis. In addition to regulation of thyroid function, TSH promotes thyroid growth. If thyroid hormone synthesis is chronically impaired, TSH stimulation eventually may lead to the development of a goiter. This chapter explores the iodide metabolism and effects of Hashimoto's disease.

Free thyroid hormone index, thyroid hormone/thyroxin-binding globulin ratio, triiodothyronine uptake, and thyroxin-binding globulin compared for diagnostic value regarding thyroid function.

1983 ◽  
Vol 29 (1) ◽  
pp. 74-79 ◽  
Author(s):  
T J Wilke
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Function ◽  
Diagnostic Value ◽  
Clinical Findings ◽  
Thyroid Function Tests ◽  
Free Thyroid Hormone ◽  
Age Related ◽  
Age Dependent ◽  
Uptake Test ◽  
The Relationship

Abstract The thyroid hormone/thyroxin-binding globulin (TBG) ratio and the free thyroid hormone index (FTI) were compared in 372 subjects classified according to age, sex, and biochemical and clinical findings. Age-related variations in thyroid function tests were investigated, as was the relationship between triiodothyronine uptake and TBG. Men, but not women, showed significant age-dependent changes in concentrations of thyroid hormones. FTI was as good as the thyroid hormone/TBG ratio in hyperthyroidism and was a better index of thyroid status in pregnancy, TBG deficiency, and hypothyroidism. In addition, the triiodothyronine uptake correlated extremely well with TBG (r = -0.95, p less than 0.001) and was very efficient in detecting decreased and significantly increased concentrations of TBG. I conclude that FTI is a better discriminator of functional status of the thyroid over a wider range of TBG values than is the thyroid hormone/TBG ratio. Further, the triiodothyronine uptake test produced diagnostic information equivalent to that of TBG estimation and thus should not be replaced in routine use.

Thyroid function in patients with Prader-Willi syndrome: an Italian multicenter study of 339 patients

2019 ◽  
Vol 32 (2) ◽  
pp. 159-165 ◽  
Author(s):  
Lorenzo Iughetti ◽  
Giulia Vivi ◽  
Antonio Balsamo ◽  
Andrea Corrias ◽  
Antonino Crinò ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Thyroid Dysfunction ◽  
Genetic Disorder ◽  
Hypogonadotropic Hypogonadism ◽  
Thyroid Stimulating Hormone ◽  
Hormone Deficiency ◽  
Published Data ◽  
Prader Willi Syndrome ◽  
Thyroid Function Tests ◽  
Central Hypothyroidism

AbstractBackgroundPrader-Willi syndrome (PWS) is a genetic disorder due to loss of expression of paternally transcribed genes of the imprinted region of chromosome 15q11-13. PWS is characterized by peculiar signs and symptoms and many endocrine abnormalities have been described (growth hormone deficiency, hypogonadotropic hypogonadism). The abnormalities of thyroid function are discussed in literature and published data are discordant. The aim of our study was to report the thyroid function in patients with PWS to identify the prevalence of thyroid dysfunction.MethodsThyroid function tests were carried out in 339 patients with PWS, aged from 0.2 to 50 years. A database was created to collect personal data, anthropometric data, thyroid function data and possible replacement therapy with L-thyroxine. Subjects were classified according to thyroid function as: euthyroidism (EuT), congenital hypothyroidism (C-HT), hypothyroidism (HT – high thyroid-stimulating hormone [TSH] and low free thyroxine [fT4]), central hypothyroidism (CE-H – low/normal TSH and low fT4), subclinical hypothyroidism (SH – high TSH and normal fT4), and hyperthyroidism (HyperT – low TSH and high fT4).ResultsTwo hundred and forty-three out of 339 PWS patients were younger than 18 years (71.7%). The prevalence of thyroid dysfunction was 13.6%. Specifically, C-HT was found in four children (1.18%), HT in six patients (1.77%), CE-H in 23 patients (6.78%), SH in 13 patients (3.83%), and HyperT in none. All other subjects were in EuT (86.4%).ConclusionsHypothyroidism is a frequent feature in subjects with PWS. Thyroid function should be regularly investigated in all PWS patients both at the diagnosis and annually during follow-up.

THYROID FUNCTION TESTS IN ADULTS WITH DOWN'S SYNDROME

1978 ◽  
Vol 88 (1) ◽  
pp. 48-54 ◽  
Author(s):  
S. Korsager ◽  
E. M. Chatham ◽  
H. P. Østergaard Kristensen
Keyword(s):  
Thyroid Function ◽  
Down's Syndrome ◽  
Clinical Signs ◽  
Down’S Syndrome ◽  
Thyroid Stimulating Hormone ◽  
Thyroid Function Tests ◽  
Thyroid Status ◽  
Biochemical Tests ◽  
Old Patients ◽  
Function Tests

ABSTRACT Thyroid status was studied in 24 patients above the age of 40 years with Down's syndrome. Three patients had thyroid function tests indicating hypothyroidism. Eight patients had thyroid autoantibodies in serum and 8 patients had a higher than normal level of thyroid stimulating hormone in serum. None of the patients had figures indicating thyrotoxicosis. None of the patients showed any of the clinical signs usually seen in patients with hypothyroidism. It is concluded that biochemical tests indicating hypothyroidism are much more often seen in patients with Down's syndrome than in normal subjects and that thyroid status should be assessed in old patients with this disease.

SIGNIFICANCE OF TRIIODOTHYRONINE FOR THYROID HORMONE SUPPLY DURING STIMULATION

1966 ◽  
Vol 53 (1) ◽  
pp. 151-161 ◽  
Author(s):  
Dieter Emrich ◽  
Peter Pfannenstiel ◽  
Günter Hoffmann ◽  
Walter Keiderling
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Thyroid Function ◽  
Hormone Production ◽  
Partial Inhibition

ABSTRACT The metabolism of the two thyroid hormones thyroxine (T4) and triiodothyronine (T3) and particularly the T4/T3 ratio was studied by the 131I technique in rats and rabbits during stimulation. Both exogenous TSH and experimentally increased endogenous TSH (secondary to the partial inhibition of thyroid function by sodiumperchlorate) caused a change in the T4/T3 ratio in favour of T3. This response of thyroid hormone production (in rats) and secretion (in rabbits) was found at different times after the use of 131I. It depended on the intensity of the direct or indirect thyrotrophic stimulation. From this observation it is suggested that the synthesis and the secretion of the biologically more effective T3 is more markedly increased during stimulation than is T4 probably in order to compensate more successfully for deficiencies in the peripheral thyroid hormone supply.

Sign in / Sign up

Export Citation Format

Share Document