A novel third-generation TSH receptor antibody (TRAb) enzyme-linked immunosorbent assay based on a murine monoclonal TSH receptor-binding antibody

Thyroid stimulating receptor autoantibodies

Thyroid-stimulating hormone receptor autoantibodies (TRAbs) play a crucial role as pathogenic antibodies in both the diagnosis and management of Graves' disease (GD). GD, an autoimmune disease resulting from a combination of genetic and environmental factors, is the most common cause of hyperthyroidism. With advancements in technology for TRAb detection and the availability of automated commercial kits, TRAb has become an essential clinical laboratory marker for the diagnosis of GD, as well as extra-thyroidal manifestations like Graves' ophthalmopathy (GO). This article provides a comprehensive review of TRAb, encompassing its clinical assays along with its significance in the clinical setting.

TSH-receptor autoantibodies in patients with chronic thyroiditis and hypothyroidism

OBJECTIVES

The reported prevalence of TSH-receptor (TSHR) autoantibodies (TRAb) in patients with chronic thyroiditis (CT) range from 0 to 48%. The objective was to study the prevalence of TRAb in patients with CT and hypothyroidism and to correlate it with gender, age, thyroid dimensions, TSH levels, and autoimmune diseases.

METHODS

The study comprised 245 patients with CT and hypothyroidism (median age 42 years, 193 females, 52 males) and 123 Italian healthy subjects matched for sex and age as controls. TRAb were tested with ELISA using a >2.5 IU/L cut off for positivity. TSHR blocking (TBAb) and TSHR stimulating autoantibodies (TSAb) were measured in 12 TRAb-positive patients using bioassays with Chinese hamster ovary (CHO) cells expressing wild-type or R255D-mutated TSHR.

RESULTS

TRAb positivity was found in 32/245 (13.1%) patients and significantly correlated (p<0.05) with TSH levels. TRAb positivity was significantly higher in males vs. females (p=0.034), in females 16-45 years of age vs. >45 years of age (p<0.05) and in patients with reduced vs. normal/increased thyroid dimensions (p<0.05). Linear regression analysis showed a correlation between TRAb concentrations with age (p<0.05) and TRAb concentrations with TSH (p<0.01). In bioassay with TSHR-R255D all 12 patients tested were TBAb-positive while 33% were also TSAb-positive suggesting the presence of a mixture of TRAbs with different biological activities in some patients.

CONCLUSIONS

TRAb have been found in patients with CT and hypothyroidism. A mixture of TBAb and TSAb was found in some patients and this may contribute to the pathogenesis of thyroid dysfunction during the course of the disease.

Comparative performance of ELISA and dot blot assay for TSH‐receptor antibody detection in Graves’ disease

Background

Graves’ disease (GD) is an autoimmune disease, and it accounts for major cases of hyperthyroidism. Antibody against thyroid‐stimulating hormone receptor/TSHR (TRAb) is responsible for hyperthyroidism and is considered as a diagnostic marker for GD. Therefore, we developed a recombinant protein of human TSHR‐169 (hTSHR‐169), which was specifically recognized TRAb in the serum of GD patients and then compare the diagnostic performance between ELISA and dot blot of TRAb tests for their ability to diagnose GD.

Methods

20 GD patients and 20 healthy individuals from the Indonesian population were enrolled. TRAb concentration and density were quantified. Comparative analysis was performed using receiver‐operating curve (ROC) analysis.

Results

For dot blot assay, the minimum concentration to detect TRAb requiring 100 ng of antigen with antiserum diluted at 1:60. For diagnosing GD, the ELISA yielded a higher AUC compared with the dot blot assay (0.95 and 0.85, respectively). Using the recommended cutoff values, the efficiency of both assays was examined by comparing the specificity and sensitivity of the assays to the clinical diagnosis. The ELISA showed 80% and 95%, while the dot blot assay showed 70% and 95% sensitivity and specificity, respectively.

Conclusion

Although the dot blot assay exhibited lower performance than the ELISA method, the dot blot assay is a simple and rapid diagnostic assay that is suitable for diagnosing GD in rural areas, in which healthcare facilities sometimes are not accessible.

The effect of radioiodine treatment on the characteristics of TRAb in Graves' disease

BACKGROUND

Graves' disease (GD) is one of the most common autoimmune thyroid diseases (AITDs) in humans, and thyrotropin receptor antibody (TRAb) is a characterized autoantibody in GD. The use of radioactive iodine therapy (RAI) for GD treatment is increasing.

OBJECTIVES

We studied the biological properties of TRAb and evaluated the effect of RAI therapy on TRAb in GD patients.

METHODS

In total, 225 patients (22 onset GD patients without ¹³¹I therapy, 203 GD patients treated with ¹³¹I therapy) and 20 healthy individuals as normal controls were included in this study. Clinical assessments were performed, and we examined in vitro the biological properties of TRAb in the 22 onset GD patients and 20 controls as well as 84 GD patients with ¹³¹I therapy.

RESULTS

Serum TRAb and thyroid peroxidase antibody (TPOAb) levels increased in the initial year of RAI treatment, and both antibodies decreased gradually after one year. After 5 years from radioiodine treatment, TRAb and TPOAb levels decreased in 88% and 65% of GD patients, respectively. The proportion of patients positive for thyroid-stimulatory antibody (TSAb) was significantly higher in the 7-12-month group, and thyroid-blocking antibody (TBAb) levels were elevated after one year in half of the patients who received ¹³¹I treatment.

CONCLUSIONS

Treatment of GD patients with radioiodine increased TPOAb and TRAb (their main biological properties were TSAbs) within the first year after therapy, and the main biological properties of elevated TRAb were TBAbs after 1 year.

Relationship between the night shift work and thyroid disorders: A systematic review and meta-analysis

OBJECTIVES

The night shift workers were reported to have health consequences, ranging from mild, as cluster headache, to severe, as heart attacks and hormonal irregularities. This study is aimed to perform a systematic review and meta-analyze of the association between the night shift work and the thyroid disorders.

METHODS

We comprehensively searched eight databases, including PubMed and Google Scholar for the relevant articles. This systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement.

RESULTS

We finally included six papers involving 4074 participants. Four papers were eligible for meta-analysis involving 1864 night shift workers and 2017 day shift workers. We against found that thyroid stimulating hormone (TSH) is significantly higher in the night shift group compared to the day shift group.

CONCLUSIONS

The higher TSH among the night shift workers is attributed to disruption of the circadian rhythm and sleep/wake cycle, with subsequent eating disorders. We proposed that more attention should be paid to the working pattern and the related health consequences.

Third generation radioimmunoassay (RIA) for TSH receptor autoantibodies (TRAb) - one step less, similar results?

AIM

 TSH-receptor (TSHR)-autoantibody (TRAb) is the serological hallmark of Graves' disease (GD). Recently, 3rd-generation radioimmunoassays (RIA) employing monoclonal TRAb such as M22 or T7 instead of TSH for the inhibition of human TRAb binding with solid-phase TSHR (coated tubes) have been introduced into laboratory routine.

METHODS

 As current assays typically employ a consecutive incubation of patient serum and labelled monoclonal TRAb, automation of TRAb RIA is a challenge. Thus, the assay procedure using human TSHR-coated tubes and the mouse monoclonal TRAb T7 was modified by combining both steps. The novel one-step method was compared with its corresponding consecutive 3rd-generation RIA by investigating 304 individuals encompassing 102 patients with active GD (GDa), 43 patients with GD after successful therapy (GDt), 31 with Hashimoto's disease (HD), 28 with non-autoimmune thyroid diseases (NAITD) and 100 healthy subjects (HS).

RESULTS

 With the new method, the incubation time was shortened by approximately one hour. Both 3rd-generation RIAs did not reveal a significantly different assay performance by comparing areas under the curve (AUC) with receiver operating characteristics curve analysis (AUC one-step: 0.94, AUC two-step: 0.96, p > 0.05, respectively). The two-step TRAb RIA demonstrated sensitivity and specificity values of 87.5 % and 96.2 %, respectively, whereas the one-step revealed 84.6 % and 96.2 %, respectively.

CONCLUSION

 One-step 3rd-generation RIA may be used for the reliable detection of TRAb. The shorter and easier assay design may improve its use and enable automation in routine nuclear medicine laboratories.