An acromegalic patient with pulsatile secretion of growth hormone (GH) coincident with the slow-wave sleep

A 43-year-old woman was admitted to our hospital for further treatment of acromegaly with high plasma GH and IGF-I levels after transsphenoidal adenomectomy and subsequent treatment with bromocriptine. Physical examination and magnetic resonance imaging (MRI) showed an active acromegalic appearance with residual pituitary macroadenoma. Laboratory findings revealed an increase in basal levels of plasma GH (21.3 microg/L) and plasma IGF-I (470 ng/ml). Plasma GH levels were suppressed from 21.3 microg/L to 9.9 microg/L following oral administration of 75 glucose and did not respond to either TRH or LHRH injection. When plasma GH levels were measured after repeated blood sampling every 20 min for 24 h and sleep stages were analyzed, there were three GH peaks during the night which corresponded to the slow-wave sleep. Mean plasma GH levels which corresponded to the slow-wave sleep stages were much greater than those of other sleep stages during the night. After the patient was treated with intermittent sc injections of octreotide (40 microg/every 2 h, 480 microg/day) in combination with oral administration of bromocriptine (15 mg/day, t.i.d.), episodic GH release was somewhat suppressed but plasma GH levels were slightly increased, corresponding to the slow-wave sleep stage during the night. Mean plasma GH levels were much higher during the sleeping period than the waking period for 24 h before and after the treatment. These findings suggest that GH secretion is correlated to the slow-wave sleep in this particular patient with pituitary GH producing adenoma.