Endocrine Abstracts

A 52-year-old gentleman was referred for the evaluation of hypercalcaemia. He gave a four week history of feeling generally unwell with dizziness, abdominal discomfort, weight loss, nausea and vomiting. He was an ex-heavy smoker and was on Lithium for about 20 years for bipolar disorder. He had had a recent admission to hospital with sepsis, secondary to chest infection, with a brief ITU stay and was discharged only 3 weeks prior to the onset of current illness.

On examination he was dehydrated, tremulous and deeply tanned with increased pigmentation of surgical scar on his knee. There was no palpable goitre, lymphadenopathy or evidence of buccal pigmentation. His vitals were stable and the rest of the examination was unremarkable.

Initial investigations revealed Na 123 mmol/l, K 6.3 mmol/l, Ur 14.9 mmol/l, Cr 172 μmol/l, Corr.Ca 3.35 mmol/l, Phos 1.81 mmol/l, Li 1.1 mmol/l (0.4–0.8). FBC, LFTs and CRP were normal.

Further investigations showed a PTH 0.9 pmol/l (1.6–6.9), TSH 0.03 mIU/l (0.35–3.5), FT₄ 33 pmol/l (8–21), FT₃ 8.9 pmol/l (3.8–6), no thyroid auto antibodies detected. Short synacthen test showed a flat response with pre-test ACTH >1000 pmol/l. In view of weight loss, hypercalcaemia and adrenal insufficiency, malignancy with adrenal metastasis was suspected. However upper GI endoscopy, CT scan of chest, abdomen and pelvis failed to show any evidence of a primary malignancy. Initial CT abdomen showed bilateral bulky adrenals which, on serial scans have shown progressive shrinkage, suggestive of adrenal infarction rather than metastasis.

A final diagnosis of lithium induced thyrotoxicosis and sepsis induced bilateral adrenal infarction with adrenal insufficiency was made. Hypercalcaemia was probably secondary to either adrenal insufficiency or thyrotoxicosis or both as it resolved with steroid supplementation and carbimazole treatment. After liasing with psychiatrists, Lithium has been gradually reduced and stopped.

Etiological diagnosis of hypercalcaemia can be challenging as illustrated by this case.