title: Urinary citrate, bone resorption and intestinal alkali absorption in stone formers with fasting hypercalciuria.
abstract: Reduced citrate in urine and increased fasting excretion of calcium are abnormalities frequently reported in stone forming (SF) patients. Increased dietary acid (or reduced alkali) introduction or absorption may be a potential cause of both these pathological findings. To test this hypothesis, we studied 64 SF patients (32 with fasting hypercalciuria (FH) and 32 without FH (NFH)). After a basal evaluation for nephrolithiasis, while on a 500 mg calcium diet, they were evaluated for: (1) daily intestinal alkali absorption (IAA), by urinary electrolyte excretion; (2) basal concentrations of PTH, calcitonin (CT) and 1,25(OH)2-VitD; (3) oral calcium load for evaluation of changes in calcium and hydroxyproline urinary excretions; (4) intestinal calcium absorption (18 patients), with double curve analysis (stable Sr as tracer); and (5) changes in citrate excretion after an alkali load (50 mEq of a mixture of calcium gluconate, lactate and carbonate) in 10 patients. The results demonstrated: (1) FH stone formers had reduced citrate excretion and lower mean IAA levels than NFH stone formers; (2) FH stone formers also had higher bone resorption levels with lower PTH and higher CT levels; (3) IAA levels were related to both citrate excretion and bone turnover indices; and (4) the increases in citrate excretion after oral alkali load were strictly related to basal IAA values (index of alkali absorption and/or generation after oral load), demonstrating that a different absorptive capacity of alkali rather than a different dietary content may underlie these metabolic abnormalities.
authors.affiliation: Nephrology-Dialysis-Transplantation Unit, Ospedale S. Maria della Misericordia, Udine, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Messa
authors.forename: G
authors.initials: G
authors.lastname: Mioni
authors.forename: L
authors.initials: L
authors.lastname: Paganin
authors.forename: A
authors.initials: A
authors.lastname: Cruciatti
authors.forename: P L
authors.initials: PL
authors.lastname: Greco
authors.forename: D
authors.initials: D
authors.lastname: Turrin
mesh_terms: D000328:Adult; D000468:Alkalies / Q000493:pharmacokinetics*; D001862:Bone Resorption / Q000097:blood / Q000652:urine*; D002116:Calcitonin / Q000097:blood; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood / Q000652:urine*; D002128:Calcium Metabolism Disorders / Q000097:blood / Q000652:urine*; D002951:Citrates / Q000652:urine*; D019343:Citric Acid; D005260:Female; D006801:Humans; D006909:Hydroxyproline / Q000652:urine; D007408:Intestinal Absorption; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D014545:Urinary Calculi / Q000097:blood / Q000652:urine*
chemical_list: D000468:Alkalies; D002951:Citrates; D010281:Parathyroid Hormone; D019343:Citric Acid; D002116:Calcitonin; D002117:Calcitriol; D006909:Hydroxyproline; D002118:Calcium