ABSTRACT
Production of the high-molecular-weight forms of adrenocorticotropic hormone (big-ACTH) has been reported in a small number of ectopic ACTH syndrome and ACTH-producing pituitary macroadenoma. However, perioperative changes in big-ACTH in patients with subclinical Cushing's disease have not been reported. A 63-year-old woman presented 25 × 20 × 20-mm-sized macroadenoma in the pituitary gland. Her early morning plasma ACTH and cortisol levels were 111 pg/mL and 11.6 µg/dL, respectively. Cushingoid features and diurnal variation in plasma cortisol levels were not observed. The patient's urinary free cortisol (UFC) was 59.3 µg/day. The corticotropin-releasing hormone (CRH) test showed that plasma ACTH levels were 1.5 times higher than the preload value. The overnight dexamethasone suppression test (DST) showed that the plasma cortisol level was not suppressed by 0.5 mg of dexamethasone (DEX) but was suppressed by 8 mg of DEX. Inferior pyramidal sinus sampling was consistent with Cushing's disease. Taken together, the patient was clinically diagnosed with subclinical Cushing's disease caused by an ACTH-producing pituitary adenoma. Endoscopic transsphenoidal adenomectomy was performed. In the postoperative CRH test, plasma ACTH levels showed six-fold increase. The postoperative DST showed cortisol suppression at 0.5 mg of DEX. The UFC levels decreased to 35.1 µg/day. Pituitary contrast-enhanced MRI revealed no residual tumor, and plasma ACTH and cortisol levels remained within normal ranges. Gel filtration of preoperative and postoperative plasma ACTH was performed, and a high molecular weight fraction of ACTH was detected, which markedly decreased postoperatively. The absence of Cushingoid features and the lack of significant cortisol hypersecretion in this case were thought to be due in part to big-ACTH, which has low bioactivity. By careful evaluation of laboratory and clinical findings, we identified it as a big-ACTH-producing adenoma. This is the first report of a case in which the big-ACTH transition was observed perioperative and is a valuable case.
ABSTRACT
A 36-year-old woman presented to the emergency room with a consciousness disorder after developing abdominal pain with diarrhea for 2 days. She presented with marked hyperglycemia, ketoacidosis, and increased serum free fatty acid (FFA) levels; however, no elevation in the glycated hemoglobin (HbA1c) levels was observed. Based on the marked depletion of insulin secretion, the patient was diagnosed as diabetic ketoacidosis attributed to fulminant type 1 diabetes (FT1D). Computed tomography on admission revealed severe fatty liver (FL), which improved 17 h following insulin treatment. Insulin treatment also suppressed the serum FFA levels. Some cases of FT1D with FL and liver dysfunction have been reported previously; however, its pathogenesis and clinical course remain unclear. Compared to previous reports, this case reported the shortest time for FL improvement. In this case, rapid and severe insulin deficiency led to a markedly high FFA level and significant accumulation of triglycerides in the hepatocytes, resulting in severe FL. A rapid and large dose of insulin was administered when systemic insulin sensitivity was nearly maximal owing to insulin deficiency, increased insulin efficacy, early reduction of FFA, suppressed triglyceride accumulation in the hepatocytes, and increased triglyceride excretion from the liver. All these factors could have contributed to the rapid improvement in FL.
