Case of hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome associated with nephrocalcinosis and distal renal tubular acidosis

Hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome is an autosomal dominant disorder characterized by hypoparathyroidism, sensorineural deafness and renal dysplasia. Herein, we report a case of HDR syndrome associated with nephrocalcinosis and distal renal tubular acidosis. A 34-year-old woman was admitted to investigate recurrent stone formation and bilateral nephrocalcinosis. As a 3-year-old child, she had been diagnosed with HDR syndrome without chromosome evaluation. She had spontaneous stone passages on several occasions. On laboratory examination, serum calcium and intact parathyroid hormone at lower levels. Urinary citrate excretion was extremely low at 51.6 mg/day. On an ammonium chloride loading test, complete distal renal tubular acidosis was proved. To prevent the nephrocalcinosis from deteriorating, she was given potassium-sodium citrate. Since administration, she has not experienced spontaneous stone passage or renal colic. Nephrocalcinosis and recurrent urolithiasis will strongly affect renal prognosis in this case and we consider that citrate medication is an effective therapy in avoiding progress of her nephrocalcinosis.