The Role of Thyrotrophin Receptor Antibody Assays in Graves’ Disease

Table 2

Recent clinical studies examining the utility of TRAb assays in predicting GD outcome.

Author (year, (ref))	Assay (𝑛)	Study design	TRAb cutoff value	% relapse	PPV %
Zimmermann- Belsing et al. (2002, [47])	TBII (129)	TRAb assays at diagnosis (122) and at withdrawal of drugs (129): median followup 18 months	1.5 U/L	45	49
Quadbeck et al. (2005, [48])	TBII (96)	TRAb assays done 4 weeks after withdrawal of drugs: followup for 2 years	1.5 U/L	49	49
			10 U/L		83
Quadbeck et al. (2005, [48])	Bioassay (96)	As above	1.5 U/L		49
					TSAb-51
Schott et al. (2007, [49])	TBII (131)	TRAb and TPOAb assays done 4.3 months (mean) after GD diagnosis	>2 and <6 U/L	71.8	66.7–90
			>6+>5000		100
			>6+>500		93.7–96
Cappelli et al. [2007, [50]]	TBII (216)	TRAb assays done at diagnosis and 6 monthly for 120 months	>46.5 U/L at diagnosis or	67.1	52%
			>30.7 U/L at 6 months		53.2
Massart et al. (2009, [51])	TBII (128)	TRAb assays compared after 18 months of treatment: 3-year followup	0.94–3.2 IU/L	48	53–66%

Most recent studies are small and retrospective. They were variable in their study design (e.g., timing of TRAb measurement), assay methodology and TRAb cutoff values used for analysis, and population characteristics (i.e., geographically disparate). Although there was a high relapse rate (45–71.8%), TRAb assay by itself had a poor PPV and was a poor predictor of relapse even when different cutoff values were used.