Polycythemia as the first manifestation of Cushing's disease

A 39-yr-old man presented to our hospital with unexplained erythrocytosis and hypertension. His follow-up for erythrocytosis had begun 2 yr earlier in another hospital and he had been diagnosed with polycythemia rubra vera. On admission to our hospital he was hypertensive (165/95 mmHg) and, except for the presence of moon-like face and facial plethora, his physical examination was normal. His hemoglobin concentration was 19.2 g/dl, and hematocrit was 58.9% with an increased red blood cell mass of 58 ml/kg as measured by radioisotope (Cr51). Blood film, other hematological indices except for elevated leukocyte alkaline phosphatase score, arterial gas analysis, and examination of aspirated bone marrow were all normal. An abdominal ultrasonography showed no evidence of splenomegaly. A diagnosis of probable secondary erythrocytosis was made. Early-morning serum cortisol and 24-h urinary free cortisol concentration as well as serum ACTH were high. Serum cortisol was not suppressed by low-dose dexamethasone, but suppressed by high-dose dexamethasone. Pituitary magnetic resonance imaging showed no lesion. After inferior petrosal sinus sampling suggesting right-central ACTH secretion, the patient underwent transnasal-transsphenoidal pituitary adenomectomy. Both hypercortisolemia and erythrocytosis regressed completely after the adenomectomy. After the operation, the patient's hemoglobin concentration and hematocrit decreased steadily, and 1 month post-adenomectomy his hemoglobin is 14.9 g/dl and hematocrit 44.8%. Thus, Cushing's syndrome should be a routine part of evaluation of unexplained polycythemia.