Transient growth hormone deficiency after treatment of primary hypothyroidism

Abstract

In primary hypothyroidism, enlargement of the pituitary sella can mimic a primary pituitary tumor on computed tomography) Enlargement of the sella, thought to represent pituitary hyperplasia and hypertrophy in response to lack of feedback inhibition of thyroid hormone, has been demonstrated in 81% of adults with primary hypothyroidism. 2 The magnitude of the sellar enlargement is proportional to thyrotropin levels, and thyroid hormone replacement therapy can produce reduction of the enlarged pituitary gland to normal size. Rarely, treatment of primary hypothyroidism has resulted in hypopituitarism? A recent report documents by CT the development of an empty sella and hypopituitarism in a child after thyroid hormone replacement because of primary hypothyroidism. 4 Hypopituitarism in the absence of empty sella syndrome has also been described after thyroid hormone replacement. In only one reported patient, an adult with primary hypothyroidism, this hypopituitarism (gonadotropin deficiency) was thought to be transient? We report two children with longstanding primary hypothyroidism who grew poorly despite adequate hormone replacement and were found to have growth hormone deficiency. Subsequently, under androgen influence and without GH therapy, growth was good and testing showed adequacy of endogenous growth hormone secretion.