THE RESPONSE OF THE THYROID GLAND TO THYROTROPIC HORMONE AS AN AID IN THE DIFFERENTIAL DIAGNOSIS OF PRIMARY AND SECONDARY HYPOTHYROIDISM*†

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Abstract
The differentiation of hypothyroidism of pituitary origin from that due to primary impairment of the thyroid gland is very difficult. An attempt at such differentiation by the admn. of thyrotropic hormone was made. 9 patients with hypometabolism were studied. One was otherwise normal, 6 were considered to have primary myxedema, and 2 had hypopituitarism. Thyroid gland function was assessed by detns. of BMR, serum protein-bound I, and by radioactive I studies. In general the patients with primary myxedema showed no response to thyrotropic hormone, whereas those with hypopituitarism did show a response. The results suggest that repeated injns. of thyrotropic hormone may be an aid in the differential diagnosis of primary and secondary hypothyroidism.