Serum thyroglobulin (Tg) stimulation with bovine TSH: a useful test for diagnosis of congenital goitrous hypothyroidism due to defective Tg synthesis.

Sixteen patients with congenital goitre were submitted to a bovine TSH stimulation test (bTSH), and serum thyroid hormones (T3, T4), TSH and thyroglobulin (Tg) were measured before and after bTSH injection. In 9 patients with an organification defect basal levels of Tg were normal (19.4 +/- 3.1 micrograms/l) rising after bTSH to a mean level +/- SEM of 37.3 +/- 4.1 micrograms/l. Six patients with defective Tg synthesis or release had a mean basal level of serum Tg of 8.7 +/- 1.9 microgram/l (mean +/- SEM) and failed to raise serum Tg concentrations after bTSH (mean +/- SEM: 10.4 +/- 2.1 micrograms/l). In both groups a modest although significant (P less than 0.05) change in serum thyroid hormones after bTSH was noted. We conclude that the bTSH test may be used to distinguish the group with defective Tg synthesis or release from other types of congenital goitre.