NEPHROLOGY – ORIGINAL PAPER Persistence of hypercalciuria after successful surgical treatment for primary hyperparathyroidism Francisco Rodolfo Spivacow • Armando Luis Negri • Elisa Elena del Valle • Erich Fradinger • Carolina Martinez • Ana Polonsky Received: 30 December 2010 / Accepted: 23 March 2011 / Published online: 20 April 2011 Ó Springer Science+Business Media, B.V. 2011 Abstract Primary hyperparathyroidism (PHPT) causes hypercalciuria and stone disease in a subset of patients. Hypercalciuria typically normalizes after surgery, although the risk of stone formation may persist up to 10 years. There are few reports in the literature that show persistent hypercalciuria despite normalization of serum calcium after parathyroid surgery. We retrospectively analyzed 111 patients with PHPT from the osteoporosis, and stone clinics seen between 1999 and 2006. We selected only patients who had a complete metabolic profile that included 24-hour collections before and at least 3 months after parathyroidectomy. We excluded patients who had creatinine clearance \ 60 ml/min/ 1.73 m 2 . Fifty-four patients were selected for further analysis, 46 with baseline hypercalciuria and 8 with normocalciuria. Changes in filtered load of calcium and fractional excretion of calcium were evaluated before and after parathyroid surgery. Total and ionized calcium and phosphorus normalized in all patients after surgery (24 ± 19 months); fractional excretion of calcium decreased, but did not normal- ize. Hypercalciuria persisted after surgery in 30.7% (n = 12/39) of the women and 50% (n = 4/8) of men. Of the patients in whom calciuria normalized after parathyroidectomy, 43.3% (n = 13/30) had kidney stones before surgery, whereas kidney stones were present in 87.5% (n = 14/16) in those in whom hypercalciuria persisted postsurgery. In hypercalciu- ric men and women before surgery in whom hyper- calciuria persisted after surgery, fractional excretion of calcium was significantly higher than that in patients with normocalciuria. Conclusions: Persis- tently increased fractional excretion of calcium could explain the sustained increased risk of stone disease in patients with PHPT for many years after successful parathyroidectomy. Keywords Primary hyperparathyroidism Á Hypercalciuria Á Renal stones Á Surgery Á Fractional calcium excretion Introduction Primary hyperparathyroidism (PHPT) is the second most frequent endocrine disease diagnosed by demonstrating persistent hypercalcemia together with elevated serum parathyroid hormone (PTH) concen- trations [1]. The estimated incidence is 1 case per 1,000 men and 2–3 cases per 1,000 women [2]. PHPT causes hypercalciuria and stone disease in a subset of patients. Before the advent of routine serum calcium F. R. Spivacow Á A. L. Negri (&) Á E. E. del Valle Á E. Fradinger Á C. Martinez Á A. Polonsky Instituto de Investigaciones Metabo ´licas, Universidad del Salvador, Libertad 836 1 piso, 1012 Buenos Aires, Argentina e-mail: negri@casasco.com.ar 123 Int Urol Nephrol (2012) 44:857–863 DOI 10.1007/s11255-011-9953-6