title: Persistence of hypercalciuria after successful surgical treatment for primary hyperparathyroidism.
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 normalize. 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 hypercalciuric men and women before surgery in whom hypercalciuria persisted after surgery, fractional excretion of calcium was significantly higher than that in patients with normocalciuria.
  
  
  CONCLUSIONS
  Persistently increased fractional excretion of calcium could explain the sustained increased risk of stone disease in patients with PHPT for many years after successful parathyroidectomy.
authors.affiliation: Instituto de Investigaciones Metabólicas, Universidad del Salvador, Libertad 836 1 piso, 1012 Buenos Aires, Argentina.
authors.forename: Francisco Rodolfo
authors.initials: FR
authors.lastname: Spivacow
authors.forename: Armando Luis
authors.initials: AL
authors.lastname: Negri
authors.forename: Elisa Elena
authors.initials: EE
authors.lastname: del Valle
authors.forename: Erich
authors.initials: E
authors.lastname: Fradinger
authors.forename: Carolina
authors.initials: C
authors.lastname: Martinez
authors.forename: Ana
authors.initials: A
authors.lastname: Polonsky
mesh_terms: D000368:Aged; D002118:Calcium / Q000097:blood / Q000652:urine; D003404:Creatinine / Q000097:blood / Q000652:urine; D005260:Female; D006801:Humans; D053565:Hypercalciuria / Q000097:blood / Q000150:complications / Q000209:etiology*; D049950:Hyperparathyroidism, Primary / Q000150:complications / Q000601:surgery / Q000652:urine*; D007669:Kidney Calculi / Q000209:etiology* / Q000652:urine; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D016105:Parathyroidectomy; D010758:Phosphorus / Q000097:blood / Q000652:urine; D011184:Postoperative Period; D057234:Preoperative Period; D012189:Retrospective Studies
chemical_list: D010281:Parathyroid Hormone; D010758:Phosphorus; D003404:Creatinine; D002118:Calcium