Pituitary macroadenoma: a rare cause of thyrotoxic hypokalaemic periodic paralysis.

Thyrotoxic hypokalaemic periodic palsy (THPP) is a well-recognised but under-diagnosed complication of hyperthyroidism and is commonly seen in Asian males. Patients usually present fully conscious with acute onset of severe motor weakness. Baseline investigation reveals severe hypokalaemia due to Na(+)/K(+) ATPase overactivity causing a massive influx of intracellular potassium ions. The most common cause of THPP identified in the medical literature is Graves' disease. We report an interesting and unusual case of THPP due to previously undiagnosed hyperthyroidism secondary to a pituitary macroadenoma. The patient was consequently found to have a tumour secreting gonadotropin and thyrotropin.