Introduction: Significant hypoglycaemia is a rare but well recognised presenting feature of secondary adrenal insufficiency. Such hypoadrenalism may be caused by intrinsic hypothalamo-pituitary disease (pituitary adenoma), exogenous steroid therapy, and uncommonly by hypophysitis and pituitary secondaries from malignant disease.
Case presentation: A 73-year-old woman presented acutely with confusion, agitation, and aggressive behaviour. She had been unwell for many months and had lost 3 kg in weight. She had ulcerative colitis, controlled with mesalazine but was on no other medication. She did not smoke and drank alcohol rarely. On examination she was thin and pale, had a pulse of 70/minute, BP 137/78, Temp 33.3 deg celsius. Systems examination was entirely normal. Paired capillary (0.3 mmol/l) and venous plasma (2.2 mmol/l) glucose were low. She was given intravenous dextrose.
Investigations - Na 131 mmol; short Synacthen test - cortisol 56 (0 min) and 297 nmol/l (30 min); adrenal antibodies −ve; plasma oestradiol 37 pmol/l, LH 0.1 mIU/ml, FSH 2.4 mIU/ml; prolactin 734 mU/L; TSH 0.81 mU/L, free T4 9.1 pmol; IGF-2/IGF-1 ratio 5 (normal <10). Insulin antibodies 2.8 (0.05.0), Gut hormone profile normal; Ca15-3 - 5581 ku/l (<32)
MRI pituitary showed a hypodense macroadenoma with a thickened stalk, and hypodense areas on the frontal bones with postcontrast enhancement. CT scans showed lucent lesions in L2 and right sacrum, but normal adrenals. Isotope bone scans confirmed secondaries in the axial and appendicular skeleton with no obvious primary. Bone biopsy confirmed secondaries from an adenocarcinoma of the breast although ultrasound breasts and mammography were normal.
Discussion: Severe hypoglycaemia is an unusual presenting feature of secondary hypoadrenalism, which needs to be considered in the differential diagnosis. This patient had partial anterior hypopituitarism likely due to pituitary metastases from a hitherto undiagnosed breast carcinoma. Although hypophysitis and pituitary adenoma are also possible, the finding of multiple bony secondaries and pituitary imaging characteristics make secondaries likely.