THYROTOXICOSIS AND HUNGRY BONE SYNDROME - A CAUSE OF POSTTREATMENT HYPOCALCEMIA

We report a case of a 54 year old woman with a history of recurrent Gr aves' disease, treated previously by thyroidectomy and later by radioi odine, who subsequently presented with tetany. Laboratory results reve aled a profound hypocalcemia (total calcium 1.00 mmol/L; ionized calci um 0.53 mmol/L) and hyperphosphatemia (2.66 mmol/L) with low levels of parathyroid hormone. Although the patient's symptoms resolved after 5 days of treatment, hypocalcemia and elevated serum levels of bone-spe cific alkaline phosphatase (ALP, EC 3.1.3.1) activity and skeletal mus cle isoenzyme (CK-MM) creatine kinase (EC 2.7.3.2) activity persisted to her discharge, 3 weeks later. Attention is drawn to the recognition and management of recalcification tetany due to the ''Hungry (for cal cium) Bone Syndrome,'' a biochemical and hormonal disturbance of calci um homeostasis and bone metabolism in the posttherapy thyrotoxic patie nt with hypoparathyroidism. This condition can be monitored by the use of calcium profile investigations, including bone-specific ALP, in ad dition to routine laboratory tests of thyroid function.