Acromegalic gigantism with low serum level of growth hormone and elevated serum insulin-like growth factor-I

In a case of acromegalic gigantism with hyperprolactinemia is reported, the basal serum growth hormone (GH) levels ranged from 1.2 to 1.9 ng/ml. Serum GH response to either insulin-induced hypoglycemia or GH-releasing hormone was blunted. Frequent blood sampling showed non-pulsatile GH secretion. Serum prolactin and insulin-like growth factor-I (IGF-I) levels were elevated. After unsuccessful surgery, bromocriptine treatment normalized serum prolactin without affecting serum GH and IGF-I levels. Combined administration of octreotide with bromocriptine reduced serum GH and IGF-I levels. In this case, non-pulsatile GH secretion and enhanced tissue sensitivity to GH may induce hypersecretion of IGF-I and cause clinical acromegalic gigantism.