An evaluation of the thyrotrophin-releasing hormone stimulation test in paediatric clinical practice.

AIM

The aim of this retrospective study was to evaluate the clinical usefulness of the thyrotropin-releasing hormone (TRH) test in children with suspected hypothalamic or pituitary dysfunction.

METHODS

We reviewed the case notes of all patients in whom a TRH test had been performed over a 6-year period. Group 1 (n = 85, 34 males, aged 0.9-18.8 years) was the reference group with no evidence of hypothalamic, pituitary or thyroid dysfunction. Group 2 (n = 42, 24 males, 0.1-18.0 years) were being investigated for possible pituitary or hypothalamic insufficiency.

RESULTS

In Group 1, thyrotropin (TSH) responses were higher in females than males (p < 0.01). In Group 2, TSH responses were normal for gender in 26 patients, subnormal in 5, and exaggerated/delayed in 11. Four patients with normal TSH responses and 4 with exaggerated/delayed responses had persistently low free thyroxine (FT(4)) or later developed low FT(4) and were treated with thyroxine. All those with subnormal TSH responses had normal FT(4) and were not treated. The TRH test did not reliably discriminate between hypothalamic and pituitary disorders.

CONCLUSIONS

The TRH test did not give useful clinical information. Clinical decisions regarding thyroxine treatment were based on FT(4), not the TRH test. The TRH test should be abandoned in paediatric practice.