A method for detecting thyroid hormone blocking immunoglobulin in a test sample from a subject, comprising a) combining i) transgenic cells stably transfected with one or more expression vector comprising a 1) first nucleic acid sequence that encodes a reporter wherein said first nucleic sequence is operably linked to a cAMP-inducible promoter, and 2) the nucleic acid sequence of SEQ ID No:2 that encodes a chimeric thyroid stimulating hormone receptor (TSHR), wherein the SEQ ID No:2 is operably linked to a constitutive promoter, wherein said cells express said chimeric TSHR on the cell membrane, ii) thyroid stimulating hormone, and iii) a sample, wherein said sample is a control sample or is a test sample, wherein said combining said transgenic cells and said TSH with A) said control sample produces a first sample, and B) said test sample produces a second sample, wherein said combining said transgenic cells and said TSH is under conditions for binding of said TSH to said chimeric TSHR, and b) measuring the level of expression of said reporter in said first sample and in said second sample, wherein a reduced level of expression of said reporter in said second sample compared to said first sample indicates the presence of TBI in said test sample. a) combining i) transgenic cells stably transfected with one or more expression vector comprising a 1) first nucleic acid sequence that encodes a reporter wherein said first nucleic sequence is operably linked to a cAMP-inducible promoter, and 2) the nucleic acid sequence of SEQ ID No:2 that encodes a chimeric thyroid stimulating hormone receptor (TSHR), wherein the SEQ ID No:2 is operably linked to a constitutive promoter, wherein said cells express said chimeric TSHR on the cell membrane, ii) thyroid stimulating hormone, and iii) a sample, wherein said sample is a control sample or is a test sample, wherein said combining said transgenic cells and said TSH with A) said control sample produces a first sample, and B) said test sample produces a second sample, wherein said combining said transgenic cells and said TSH is under conditions for binding of said TSH to said chimeric TSHR, and i) transgenic cells stably transfected with one or more expression vector comprising a 1) first nucleic acid sequence that encodes a reporter wherein said first nucleic sequence is operably linked to a cAMP-inducible promoter, and 2) the nucleic acid sequence of SEQ ID No:2 that encodes a chimeric thyroid stimulating hormone receptor (TSHR), wherein the SEQ ID No:2 is operably linked to a constitutive promoter, wherein said cells express said chimeric TSHR on the cell membrane, 1) first nucleic acid sequence that encodes a reporter wherein said first nucleic sequence is operably linked to a cAMP-inducible promoter, and 2) the nucleic acid sequence of SEQ ID No:2 that encodes a chimeric thyroid stimulating hormone receptor (TSHR), wherein the SEQ ID No:2 is operably linked to a constitutive promoter, wherein said cells express said chimeric TSHR on the cell membrane, ii) thyroid stimulating hormone, and iii) a sample, wherein said sample is a control sample or is a test sample, wherein said combining said transgenic cells and said TSH with A) said control sample produces a first sample, and B) said test sample produces a second sample, wherein said combining said transgenic cells and said TSH is under conditions for binding of said TSH to said chimeric TSHR, and A) said control sample produces a first sample, and B) said test sample produces a second sample, wherein said combining said transgenic cells and said TSH is under conditions for binding of said TSH to said chimeric TSHR, and b) measuring the level of expression of said reporter in said first sample and in said second sample, wherein a reduced level of expression of said reporter in said second sample compared to said first sample indicates the presence of TBI in said test sample.