Computed tomography of the pituitary fossa in primary hypothyroidism. Effect of thyroxine treatment.

Computed tomography of the pituitary fossa was performed in 12 patients with primary hypothyroidism before and after thyroxine treatment. In three, herniation of the diaphragma sellae precluded accurate measurement of the density of the hypophysis. Eight of the remaining patients showed abnormally increased density of the pituitary gland after intravenous injection of contrast substance which was significantly correlated with the serum TSH-level (r = 0.913, P less than 0.001). After thyroxine treatment the intrasellar density decreased substantially in all but one. We suggest that the observed contrast enhancement reflects increased pituitary circulation associated with the augmented function of TSH-producing cells in response to thyroid hormone deficiency.