Hypoparathyroidism--presenting 40 years after thyroid surgery.

Serum calcium was 1.25 mmol/L (normal range 2.10-2.60 mmol/L); phosphate 1.97 mmol/L (normal range 0.8-1.55 mmol/L); alkaline phosphatase 134u/L (35-120 u/L); magnesium 0.61 mmol/L (0.70-1.03 mmol/L); T4 27.9 pmol/ L (7.6-19.7 pmol/L); T3 1.9 pmol/L (1.5-3.0 pmol/L); TSH 0.02 mU/L (0.4-4.5 MU/L); parathyroid hormone <10 ng/L (10-50 ng/L). Full blood count, renal function and autoantibody screen were normal. An electrocardiogram showed a prolonged QT interval of 568 msecs.