Thyroid-stimulating Hormone Assay Research Articles

A multi-analyte immunoassay for thyroid related analytes

ABSTRACTWe describe the development and validation of multianalyte immunoassays (MAIA) for three analytes, viz., thyroxine (T4), thyroid stimulating hormone (TSH), and thyroglobulin (Tg) essential for assessment of thyroid function but having widely varying molecular weights. Using polycarbonate (PC) track-etched membranes (TEM) as an immobilization support and 125I as the tracer, both competitive assay for T4 and non-competitive assay for TSH and Tg were performed on the same TEM. MAIA was found to be highly sensitive and precise with clinically useful working range and correlated very well with individual analyte immunoassays. While we have demonstrated this assay format with radiotracer, it can be used with non-isotopic tracers equally well.

Evidence or enthusiasm? Why yields from UK newborn screening programmes for congenital hypothyroidism are increasing

Newborn screening for congenital hypothyroidism (CHT) is generally regarded as a highly successful public health measure. It was officially added to the UK newborn screening programme for phenylketonuria in 19811...

Evaluation of thyroid-stimulating hormone, total thyroxine, and free thyroxine concentrations in hyperthyroid cats receiving methimazole treatment.

BackgroundIatrogenic hypothyroidism (IH) after treatment of hyperthyroidism can impair renal function. No study compared the efficacy of measurement of serum free thyroxine by equilibrium dialysis (fT4ed) or thyroid‐stimulating hormone (TSH) concentrations for monitoring cats receiving methimazole.ObjectivesTo (1) compare the ability of total T4 and fT4ed concentrations in conjunction with TSH to define thyroid function in hyperthyroid cats receiving methimazole, (2) determine the prevalence of IH in cats receiving methimazole, and (3) examine the relationship between thyroid axis hormones and serum creatinine concentration.AnimalsOne hundred and twenty‐five serum samples from hyperthyroid cats receiving methimazole and total T4 concentrations ≤3.9 μg/dL.MethodsTotal T4, fT4ed, and TSH concentrations were measured to evaluate thyroid status and serum creatinine concentration was measured to assess renal function. A low total T4 or fT4ed concentration in combination with an increased TSH concentration defined IH.ResultsForty‐one cats (33%) had increased TSH concentrations. Of cats with total T4 and fT4ed concentrations below the reference range, 68% and 73%, respectively, had TSH concentrations above the reference range. Only 18% of cats with a normal TSH concentration had an increased serum creatinine concentrations as compared to 39% of those with increased TSH concentrations (P < .001).ConclusionsFree T4ed does not identify more cats with potential IH as compared to total T4. The IH prevalence was approximately 20%. Measurement of TSH may be more helpful in indicating that azotemia, if present, is at least in part related to IH. Investigation is needed to define TSH assay utility in identifying possible subclinical IH.

Increased TSH in obesity: Evidence for a BMI-independent association with leptin

AimThis study aimed to determine whether the association between thyroid-stimulating hormone (TSH) and body mass index (BMI) is related to leptin concentration in obese individuals. MethodsPlasma TSH and leptin assays were performed in 800 consecutive patients, hospitalized for a nutritional checkup, with a BMI≥30kg/m2. Various anthropometric, hormonal and metabolic parameters, including age, weight, BMI, insulin, leptin and TSH, were measured or calculated. Univariate and multivariate regression analyses were performed to identify any significant relationships between these parameters. Also, characteristics of the patients in the lowest and highest quartiles of TSH distribution were compared. ResultsTSH was positively correlated with both BMI and leptin. When multiple regression analysis was performed, TSH and leptin maintained a significant association independent of BMI. Patients in the fourth quartile of TSH distribution displayed higher BMI and higher leptin levels in comparison to the first quartile. ConclusionOur study has confirmed an increase in TSH in conjunction with BMI in obese subjects. This increase was correlated with leptin independently of BMI. It is hypothesized that the increase in TSH observed in obese subjects was the consequence of both fat mass accumulation and a positive energy-balance.

Label-free and rapid electrical detection of hTSH with CMOS-compatible silicon nanowire transistor arrays.

Now a human thyroid stimulating hormone (hTSH) assay has been considered as a screening tool for thyroid disease. However, some existing methods employed for in-hospital diagnosis still suffer from labor-intensive experimental steps, and expensive instrumentation. It is of great significance to meet the ever growing demand for development of label-free, disposable, and low-cost productive hTSH detection biosensors. Herein, we demonstrate a novel sensing strategy for highly sensitive and selective immunodetection of hTSH by using a CMOS-compatible silicon nanowire field effect transistor (SiNW-FET) device. The SiNW chips were manufactured by a top-down approach, allowing for the possibility of low-cost and large-scale production. By using the antibody-functionalized SiNW-FET nanosensors, we performed the label-free and rapid electrical detection of hTSH without any nanoparticle conjugation or signal amplifications. The proposed SiNW biosensor could detect hTSH binding down to a concentration of at least 0.02 mIU/L (0.11 pM), which is more sensitive than other sensing techniques. We also investigated the influence of Debye screening with varied ionic strength on hTSH detection sensitivity, and real-time measurements on various concentrations of the diluted buffer. The simple, label-free, low-cost, and miniaturized SiNW-FET chip has a potential perspective in point-of-care diagnosis of thyroid disease.

Affinity assisted selection of antibodies for Point of Care TSH immunoassay with limited wash

BackgroundMolecular binding characteristics of several thyroid stimulating hormone (TSH) antibodies were determined for the TSH antigen, along with its closely related endogenous interfering hormones, follicle stimulating hormone (FSH), luteinizing hormone (LH) and chorionic gonadotropin (CG). MethodsThis data was compared to the same antibodies used in the low wash sandwich ELISA immunoassay system, the Point of Care i-STAT® immunoassay. From this information we developed binding criteria useful in the low wash i-STAT® immunoassay to permit good signal generation from TSH and low cross-reactivity from its interfering hormones. For the TSH Assay we have developed characteristics that enable antibody selection in the i-STAT® immunoassay cartridge. Our antibody screening approach used a dot blot approach as a first screen to select for the most useful antibodies. We then compared a FRET (Förster Resonance Energy Transfer) and electrochemical cartridge approach to determine the appropriate antibody combinations. ResultsBoth methods generated similar data, but the FRET method was not capable of differentiating the antibody with the best characteristics as a capture antibody or a detection conjugate in a sandwich ELISA assay. Finally, we performed binding characterizations of the antibodies using each of the above mentioned glycoproteins. ConclusionsWe found that we need sub-picomolar detection of TSH, and at least 100 fold or higher values for the cross-reacting species.

Prevalence of unknown thyroid disorders in a Sardinian cohort.

To assess thyroid function, the presence of thyroid antibodies, as well as the presence of goiter and/or nodules in subjects without a prior diagnosis of thyroid disorders, in a region with mild to moderate iodine deficiency. This cross-sectional study is based on data obtained from first and third visits of participants in the Sardinian survey. We performed two different analyses. In one, we assessed the prevalence of unknown thyroid dysfunctions among 6252 subjects who had a medical examination and blood collection for assays of thyrotropin, free thyroxine, and antibodies against thyroperoxidase (AbTPO) and against thyroglobulin (AbTG). In a second analysis, we evaluated the frequency of undiagnosed goiter and nodules among 3377 subjects who had a thyroid ultrasound scan. Subjects were excluded if they had a previous history of thyroid disorders or presence of goiter and/or nodules, or thyroid surgery, or if they were taking drugs that could impair thyroid function. We found a low prevalence of overt thyroid dysfunction (hyperthyroidism 0.4% and hypothyroidism 0.7%). The rates of subclinical hypothyroidism and hyperthyroidism were 4.7 and 2.4% respectively. Almost 16% of participants were positive for at least one antibody and 5.2% for both AbTG and AbTPO. Nodules were detected in 17.4% of subjects and the prevalence of goiter was 22.1%. Undiagnosed biochemical thyroid dysfunctions, unknown nodules, and goiter were common in subjects living in a mild to moderate iodine-deficient area. In this community, thyroid disorders often go undetected and screening could be reasonable in subjects at a higher risk.

Role of thyrotropin-releasing hormone test in re-evaluation of congenital hypothyroidism

The thyrotropin-releasing hormone (TRH) test is useful for differentiating central and primary hypothyroidism, and is also valuable for diagnosing hypothyroidism. The threshold of the TRH test is usually set at 10–40 mIU/L. However, some experts are of the opinion that the TRH test has a limited role in evaluating hypothyroidism because of the clinical application of the new-generation thyroid-stimulating hormone (TSH) assay. We reviewed a case series to analyze the clinical use of the TRH test in the re-evaluation of congenital hypothyroidism. In total, data on 228 children with eutopic thyroid glands and neonatal hyperthyrotropinemia under levothyroxine replacement were collected. Basal TSH levels were measured and the TRH test was performed at the age of 3 years for re-evaluation of congenital hypothyroidism, and statistical analysis was performed. All of the patients were followed up to avoid over- or under-treatment. At the age of 3 years, 31.6% of the patients still had hypothyroidism. There was no significant difference between basal TSH level and TRH test in the diagnosis of hypothyroidism (p = 0.23). The negative predictive value of the basal TSH level was 100%, however, the positive predictive value was only 43.6%. When the TSH level was near the upper limit of the normal range (4.5–8.5 mIU/L), the TRH test result had a better correlation with hypothyroidism than the basal TSH level (p = 0.03). The threshold of the TRH test set at 60 mIU/L had the greatest area under the curve, with a negative predictive value of 95.2% and a positive predictive value of 80.2%. Neonatal hyperthyrotropinemia was a risk factor for hypothyroidism. We suggest that the TRH test should be administered in children with a basal TSH value near the upper limit of the normal range, and the threshold of the TRH test should be set at 60 mIU/L.

Thyroid stimulating hormone assay as the first line biochemical parameter to determine thyroid gland abnormalities.

Increased cellular catabolic activities observed in hyperthyroid state had been established. This is consequent to excessive hormones secreted by the thyroid gland during this condition. A total of 60 subjects comprising of 45 females mean age 43.02 +/- 1.90 (range 22-70 years) and 15 males mean age 50.40 +/- 3.59 (range 25-68) and 60 controls comprising of 45 females mean age 41.18 +/- 1.68 (range 22-68 years) and 15 males mean age 40.53 +/- 2.88 (range 25-65) were recruited for the study. The plasma level of T4, T3 and TSH were determined in both the experiment group and the controls. A significant increase (p < 0.05) in plasma T4, T3 and a significant decrease (p < 0.05) in plasma TSH were observed in the experiment group in comparison to the controls. Also, an inverse relationship was noted to exist between the plasma T4 and T3; and TSH in primary hyperthyroid state.

Fluorescence immunochip assay for thyroid stimulating hormone in whole blood

The determination of blood level of thyroid stimulating hormone (TSH) is an important biomarker for the clinical assessment of thyroid status. Here, we presented a new fluorescence (FL) immunochip TSH assay system, which was developed with a platform of point-of-care test (POCT) for clinical applications. The assay system adopted a lateral-flow immunochromatographic technology and consisted of anti-TSH-mAb coated strip in a disposable chip, a detection buffer containing FL-labeled anti-TSH-pAb, a calibration chip, and a laser FL scanner. The analytical performance of FL immunochip TSH assay system was evaluated by linearity, interference, recovery, and imprecision tests. The comparability of the developed assay was examined with an automated reference assay. The developed assay system exhibited an excellent linearity in working range of 1–100 μIU/mL and was affected neither a large amount of various serum interference substances nor similar structure biomolecules to TSH. The analytical mean recovery of control was 97.6% in a dynamic working range and the imprecision of intra- and inter-assay of CVs was less than 10%. There was a significant correlation between the developed TSH assay and the Beckman Coulter Access 2 TSH assay (r=0.989, p<0.001). The developed FL immunochip assay is the only method that quantifies TSH concentration in whole blood and meets the criteria of POCT including affordable cost, a disposable device, and requiring minimum maintenance to perform test.

Myxoedema Coma: A Very Rare Presentation of Severe Hypothyroidism

Myxoedema coma is a rare and life threatening medical emergency with a high mortality rate. It results from severe hypothyroidism and affects almost every organ system. The salient features of myxoedema coma are decreased mental status and hypothermia, but other characteristics of severe hypothyroidism are usually present including bradycardia, hypotension, hypoglycemia and hypoventilation. Abnormal accumulation of mucin in skin and other tissues can lead to typical clinical features , for example nonpitting oedema, swollen lips, enlarged tongue and thickened nose. Diagnosis is challenging due to the paucity of cases and possibly earlier recognition of hypothyroidism as a result of improved availability of thyrotropin (TSH) assays. Clinicians can be mislead by the misnomer “coma” as patients may present with signs of cognitive impairment such as agitation, confusion and disorientation. A high index of suspicions is needed among clinicians in order to rapidly recognize the condition and make an early diagnosis. Treatment should be commenced on clinical grounds while waiting for laboratory results. It is also vital that these patients receive intensive care level treatment with close monitoring of their cardiovascular parameters and level of consciousness. In addition, severe hypothyroidism can decompensate to myxoedema coma as a result of precipitating factors, for example cold exposure, alcohol, sedative drugs, sepsis or myocardial infarction. Therefore, it is important to address and try to reverse any of these precipitants. doi: http://dx.doi.org/10.4021/ jmc1503w

Thyroid testing in pregnant women with thyroid dysfunction in Tayside, Scotland: the thyroid epidemiology, audit and research study (TEARS)

To investigate the rate of thyroid testing during pregnancy. Population-based, retrospective record-linkage study. Health care data on pregnant women in Tayside, Scotland. All pregnant women who were 18 years and above and who delivered between 1 January 1993 and 31 March 2011 in Tayside were identified. Patients were included in the study if they have had at least three thyroxine prescriptions prior to pregnancy of which at least one prescription was within 6 months prior to pregnancy. Number of thyroid-stimulating hormone (TSH) assays performed during pregnancy and the changes in dosage of thyroxine prescribed during pregnancy. We identified 950 pregnancies that had thyroxine prescribed prior to pregnancy. Overall, 96.9% (95% CI: 96-98) of these pregnancies had at least one TSH assay performed during or just prior to pregnancy, with 81.2% (95% CI: 79-84) in the first trimester. The prescription of thyroxine was increased in 60.0% (95% CI: 57-63) at any time during pregnancy and in 34.0% (95% CI: 31-37) of pregnancies during the first trimester. Overall, 60% (95% CI: 57-63) of pregnancies had at least one elevated serum TSH during pregnancy with 55% (95% CI: 51-58) in the first trimester. The TSH concentration is raised in many pregnancies in women taking long-term thyroxine.

Experimental evaluation of the impact of maternal consumption of aqueous leaf extract of Hybanthus enneaspermus on pregnancy in Sprague dawley rats

The impact of aqueous leaf extract of Hybanthus enneaspermus (HEaq) on pregnancy factors and litter survival was investigated in Sprague Dawley (SD) rat. Control group received distilled water while the test group received 2g/kg body weight of HEaq orally. Blood samples were collected on days one and twenty of pregnancy for total blood count, serum thyroid hormone, thyroid stimulating hormone (TSH) and thyrotropin releasing hormone (TRH) assay. Half the number of rats in each group was sacrificed on day nineteen of pregnancy and the placenta and foetus were removed and weighed. The second half carried their pregnancy to term. Number and weights of litter were recorded at birth and the litter were also subjected to righting reflex test. Post-natal survival rate was determined for each group while effect of HEaq was also examined in-vivo on the activities of pregnant myometrial muscle. HEaq significantly decreased (p<0.05) foetal weight, placenta weight, foetal growth and survival, number and weights of litter at birth, maternal serum triiodotyroxine T3 and TSH level. Mean corpuscular haemoglobin, white blood cell count, platelet count and lipid profile were significantly increased (P<0.05). HEaq increased the frequency and percentage contraction of gravid myometrial muscle in a dose dependent manner. Maternal consumption of aqueous leaf extract of Hybanthus enneaspermus adversely affected pregnancy and development of the foetus, as it precipitated resorption of developing foetus and reduced size and weight of litter at term.

Evaluation of upper reference limit of TSH in adults: Review of biological upper reference limit for TSH on a "chemiluminescence based" analysis technique

Background: There was an identified need to review the use of the manufacturer provided upper reference limit (URL) of the thyroid stimulating hormone (TSH) assay for the Indian population. URL's provided by manufacturers are usually based on western populations. This study triggered from our clinical feedback, identified that there is indeed difference for the URL for the Indian population compared to what the manufacturer has provided for the TSH assay. Materials and Method: Prospective study with volunteers from St. John's Medial College Hospital general health check who were pre-screened and selected based on inclusion/exclusion criteria decided for the purpose. We utilised the Access ® range of Chemiluminescence based Immuno assay system from Beckman Coulter Inc., Brea. CA, USA for this study. As indicated in the background, we investigated URL of the TSH assay. Results and Conclusion: Results strongly favored the reduction of the URL to be more suitable for the population covered in this study.

Myxoedema Coma: A Very Rare Presentation of Severe Hypothyroidism

Myxoedema coma is a rare and life threatening medical emergency with a high mortality rate. It results from severe hypothyroidism and affects almost every organ system. The salient features of myxoedema coma are decreased mental status and hypothermia, but other characteristics of severe hypothyroidism are usually present including bradycardia, hypotension, hypoglycemia and hypoventilation. Abnormal accumulation of mucin in skin and other tissues can lead to typical clinical features, for example nonpitting oedema, swollen lips, enlarged tongue and thickened nose. Diagnosis is challenging due to the paucity of cases and possibly earlier recognition of hypothyroidism as a result of improved availability of thyrotropin (TSH) assays. Clinicians can be mislead by the misnomer “coma” as patients may present with signs of cognitive impairment such as agitation, confusion and disorientation. A high index of suspicions is needed among clinicians in order to rapidly recognize the condition and make an early diagnosis. Treatment should be commenced on clinical grounds while waiting for laboratory results. It is also vital that these patients receive intensive care level treatment with close monitoring of their cardiovascular parameters and level of consciousness. In addition, severe hypothyroidism can decompensate to myxoedema coma as a result of precipitating factors, for example cold exposure, alcohol, sedative drugs, sepsis or myocardial infarction. Therefore, it is important to address and try to reverse any of these precipitants. J Med Cases. 2013;4(11):715-718 doi: https://doi.org/10.4021/jmc1503w

Neonatal Thyroid-Stimulating Hormone Concentrations in Belgium: A Useful Indicator for Detecting Mild Iodine Deficiency?

It has been proposed that neonatal thyroid-stimulating hormone (TSH) concentrations are a good indicator of iodine deficiency in the population. A frequency of neonatal TSH concentrations above 5 mU/L below 3% has been proposed as the threshold indicating iodine sufficiency. The objective of the present study was to evaluate feasibility and usefulness of nation-wide neonatal TSH concentration screening results to assess iodine status in Belgium. All newborns born in Belgium during the period 2009–2011 (n = 377713) were included in the study, except those suffering from congenital hypothyroidism and premature neonates. The frequency of neonatal TSH concentrations above 5 mU/L from 2009 to 2011 in Belgium fluctuated between 2.6 and 3.3% in the centres using the same TSH assay. There was a significant inverse association between neonatal TSH level and birth weight. The longer the duration between birth and screening, the lower the TSH level. Neonatal TSH levels were significantly lower in winter than in spring or autumn and significantly lower in spring and summer than in autumn while significantly higher in spring compared to summer. In conclusion, despite that pregnant women in Belgium are mildly iodine deficient, the frequency of neonatal TSH concentrations above 5 mU/L was very low, suggesting that the neonatal TSH threshold proposed for detecting iodine deficiency needs to be re-evaluated. Although neonatal TSH is useful to detect severe iodine deficiency, it should not be recommended presently for the evaluation of iodine status in mildly iodine deficient regions.

Identification and characterization of an antibody-bound thyroid-stimulating hormone (TSH) with differential effects on various clinically available serum TSH assays

Identification and characterization of an antibody-bound thyroid-stimulating hormone (TSH) with differential effects on various clinically available serum TSH assays

Prevalence, Associated Risk Factors and Effects of Hypothyroidism in Pregnancy: A Study from North India

Background and Objective: There is a controversy regarding universal versus targeted screening for hypothyroidism during pregnancy. We studied the prevalence and the associated risk factors of hypothyroidism. The secondary objective of the study was to compare the maternal and perinatal outcomes in overt and subclinical hypothyroidism. Methods: We screened 1,005 antenatal patients for hypothyroidism with a thyrotropin assay. Patients diagnosed with hypothyroidism were further tested for anti-thyroid peroxidase antibodies and free thyroxin to determine the cause and type (overt or subclinical) of hypothyroidism. Maternal and perinatal outcomes were compared in the overt, subclinical and euthyroid groups. Results: The overall prevalence of hypothyroidism was 6.3% (overt 2.9% and subclinical 3.4%). Thirty-four (3.4%) new hypothyroid cases could be detected by universal screening. The risk factors for thyroid dysfunction were not significantly different in the screen-positive versus screen-negative patients except for excessive weight gain (p = 0.00). Targeted screening could have missed one third of subclinical hypothyroid cases. Gestational hypertension was significantly greater in the overt hypothyroid group (p = 0.007), and more patients required induction in this group (p = 0.013) but other maternal complications and perinatal outcomes were similar. Conclusion: We recommend universal screening for hypothyroidism in pregnancy in our population, as the prevalence of hypothyroidism is high.

Application of europium(III) chelates-bonded silica nanoparticle in time-resolved immunofluorometric detection assay for human thyroid stimulating hormone

Eu(III) chelate-bonded silica nanoparticle was used as a fluorescent label to develop a highly sensitive time-resolved immunofluorometric assay (TrIFA) for human thyroid stimulating hormone (hTSH). The limit of detection of the assay calculated according to the 2SD method was 0.0007mIUL−1 and became 0.003mIUL−1 when serum-based matrix was used for calibrators, indicating that this TrIFA is comparable with the most sensitive assays. The linear range was from 0.005 to 100mIUL−1 of hTSH with coefficient of variation between 1.9% and 8.3%. The correlation study using 204 blood spot samples from newborns showed that the results from this new method were coincident with that of the commercial dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA) system, with a correlation coefficient of 0.938. The fluorescent nanoparticle label allows directly reading the fluorescent signal, omitting the signal development step required for the DELFIA system, and the whole procedure of this assay is fulfilled within 2h. Thus, we developed a novel, sensitive, quantitative and simple nanoparticle label-based TrIFA assay, suitable for routine application in hTSH screening of neonatal hypothyroidism.

TSH - Clinical Aspects of its Use in Determining Thyroid Disease in the Elderly How does it Impact the Practice of Medicine in Aging?

The last four decades have seen enormous growth in the efficacy of serum thyroid stimulating hormone (thyrotropin, TSH) assay methodology, establishing TSH as the hallmark of thyroid testing. At the center of the considerations is the strong inverse correlation between serum thyrotropin and free thyroxine concentrations. While it is widely accepted that elevated serum TSH concentrations are consistent with thyroid dysfunction, a vast multitude of additional factors must be considered before an accurate clinical diagnosis can be made followed by an appropriate treatment. Epidemiological studies have demonstrated slightly elevated serum TSH concentrations among the elderly population. There is, however, a debate whether these elevated TSH levels reflect an increased prevalence of hypothyroidism among the elderly or a normal aspect of healthy aging. A comprehensive analysis of the many variables associated with this debate and TSH measurement as a diagnostic tool in aging should provide insight into the clinical efforts to diagnose and treat thyroid disease, particularly in the elderly population.