Abstract. We used octreotide to treat a woman with acromegaly and observed pituitary adenoma shrinkage after 5 months.Diffuse scalp hair loss occurred after 5 months, resulting in the discontinuation of treatment. After the cessation of octreotide, the hair loss stopped and hair growth resumed. Since bromocriptine did not effectively decrease the GH level of the patient, we decided to perform transsphenoidal surgery. After resection of the pituitary adenoma, her GH and IGF-1 levels were normalized. Although octreotide-induced scalp hair loss has not been well recognized, we should pay more attention to this side effect.Key words: Acromegaly, Octreotide, Hair loss (Endocrine Journal 42: 385-389,1995) THE USE of octreotide, a somatostatin analog, for the treatment of acromegaly is widely established [1]. The most common adverse effect of octreotide is pain at the site of injection, cholecystlithiasis and gastrointestinal symptoms such as abdominal cramps, nausea, bloating, flatulence, diarrhea and steatorrhea [2,3]. Hair loss caused by octreotide administration has rarely been reported [4]. We describe a patient with acromegaly who was successfully treated with octreotide, achieving a reduction in pituitary adenoma size. However, after five months of octreotide administration, hair loss occurred and we had to discontinue the drug. After the cessation of octreotide, hair growth resumed. March, 1993. She had spondylosis deformance that had been conservatively treated for 20 years. Although she had noticed that she had to wear larger shoes than before, she thought it was caused by weight gain (45 to 68 kg). When she visited a physician because of a cold, acromegalic facial features, and high serum levels of GH (5.7 ng/ml) and IGF-1(6.8 U/ml) were pointed out. She was suspected of having acromegaly and was referred to our clinic. On physical examination, she was obese (157.4 cm in height, 80.0 kg in weight, with a body mass index of 32.3 kg/m2) and her blood pressure was 106/60 mmHg. Her face appeared to be acromegalic, with protrusion of the jaw and eyebrows, and acrodactylia was noted. She had goiter, and her chest and abdomen were normal. There were no abnormal findings on neurological examination. No visual field defects were detected. No hair loss was seen on admission. With respect to laboratory findings, urinalysis revealed no abnormalities.Peripheral blood examination showed mild anemia with an Hb level of 11.5 g/ dl. The fasting blood sugar level of the patient was 114 mg/dl. Serological results included a mi-
