Endocrine Abstracts

Introduction: Cyclic Cushing’s syndrome (CS) is a rare disorder characterized by repeated episodes of cortisol excess interspersed by periods of normal cortisol secretion. These phases may range from days to years. The diagnosis is a difficult challenge.

Case report: We present a case of 56-year-old women with hyperglycemia, hypertension, central obesity, edema, bruising, fatigue and emotional lability for several years. Laboratory tests: glucose 141, HbA1c 11%, LDL-cholesterol 121, HDL-cholesterol 84, triglycerides 95, Na 143 and K 3.3, 24-hour urinary free cortisol 662 μg (4.3–176), cortisol rhythm with basal serum cortisol 9 h 8.5 and 21 h 24 μg/dl, 1-mg overnight dexametasone suppression test revealed a morning serum cortisol concentration of 18.6 μg/dl (<1.8), ACTH 75 pg/ml (5–50) and 8-mg overnight suppression test pointed a pretreatment morning serum cortisol 30.1 which was suppressed to 6.8 μg/dl (71%). Pituitary magnetic resonance was normal. Inferior petrosal sinus sampling (IPSS) was ordered but it was cancelled because clinical and biochemical hypercortisolism disappeared. Three months later, hypercortisolism appeared and immediately IPSS was made. IPSS was diagnosis of a central source for ACTH secretion. The patient was treated successfully with transsphenoidal hypophysectomy. Histopathology revealed a 4.5 mm pituitary corticotroph microadenoma. After that, there were normalization of the hypercortisolism and the phenotype but hypopituitarism was established.

Conclusions: The diagnosis of cyclic CS is difficult to make given the variations in clinical presentation, the unpredictability of cyclic secretion and the lack of uniformity in etiology. Causes of cyclic CS are multiple dominated by pituitary adenoma. Patients can have periods of clinical improvement during these quiescent phases or remain symptomatic. IPSS should be made only when biochemical hypercortisolism is present at the same time.