[Indications for oral TRH in a study of 998 patients (author's transl)]

The authors determined values for T3, T4, T7, T3RIA and basal TSH, as well as TSH stimulation after intravenous administration of TRH in 998 patients. The test was negative in 259 patients (26%); in 51 of these patients (5.1%) no clinical or laboratory reasons could be found (low- or non-responders). In this group of patients the TRH test was repeated using a hundred times greater dose orally; in 27 cases (54%) of the low- or non-responders the oral test proved positive. In total, the TRH test was positive in 76.8%, negative in 20.9% and there were 2.3% non-responders. It was concluded that the oral test is more informative than the intravenous. Since the intravenous test gives poor results in only 5.1% of euthyroid patients, the extra effort appears hardly worth while. Further, failure of the intravenous TRH tests should lead to a repetition of the TRH test using oral application before a radioiodine test is done, since this will clarify more than half the tests with negative results.