title: Acute oral calcium-sodium citrate load in healthy males. Effects on acid-base and mineral metabolism, oxalate and other risk factors of stone formation in urine.
abstract: The currently preferred calcium preparations for supplementation of food vary widely with respect to calcium availability, effects on systemic mineral metabolism, acid-base status, and the calciuria-induced risk of urinary tract stone formation. In eight healthy males we studied the response to an acute load with alkali(sodium)-containing soluble calcium citrate (CSC) (molar ratio calcium/sodium/citrate approx. = 1/1/1), when taken in three different doses (10, 20, 30 mmol calcium) together with a continental breakfast. Intestinal calcium absorption, serum calcium, calcitonin, parathyroid hormone (PTH) other markers of bone metabolism, net acid excretion and calcium oxalate crystallization in urine were evaluated. CSC evoked a dose-dependent increase in calcium absorption, calcium in serum and urine, but no overt hypercalcemia, and calciuria was low relative to the excess calcium ingested; PTH fell and calcitonin rose (p < 0.05 vs. breakfast alone), but the diet-independent markers of bone resorption declined only insignificantly, while the markers of bone formation and turnover remained unchanged. There was a significant "once-daily" effect (= cumulative 24 h postload response) of CSC: a decrease in urinary cyclic AMP, phosphorus, and ammonium, and an increase in urinary bicarbonate. Soon after CSC intake, urinary calcium oxalate and hydroxyapatite supersaturation increased dose-dependently, the calcium oxalate crystal diameter was increased, but crystal aggregation time, which is crucial for stone formation, remained statistically unchanged. Thus, CSC provides calcium in a bioavailable form, creates mild systemic alkalinisation and inhibition of bone resorption, but leaves the risk of developing urinary stones unchanged. Comparative long-term studies on bone growth and the maintenance of bone health, using alkali-containing versus alkali-free calcium citrate, appear worthwhile.
authors.affiliation: Department of Surgery, University of Erlangen, Germany.
authors.forename: P O
authors.initials: PO
authors.lastname: Schwille
authors.forename: A
authors.initials: A
authors.lastname: Schmiedl
authors.forename: U
authors.initials: U
authors.lastname: Herrmann
authors.forename: R
authors.initials: R
authors.lastname: Schwille
authors.forename: E
authors.initials: E
authors.lastname: Fink
authors.forename: M
authors.initials: M
authors.lastname: Manoharan
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D001682:Biological Availability; D001842:Bone and Bones / Q000378:metabolism; D019355:Calcium Citrate / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D002129:Calcium Oxalate / Q000378:metabolism* / Q000652:urine; D003460:Crystallization; D019587:Dietary Supplements; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D008297:Male; D008903:Minerals / Q000378:metabolism*; D019518:Postprandial Period; D012307:Risk Factors
chemical_list: D000975:Antioxidants; D008903:Minerals; D002129:Calcium Oxalate; D019355:Calcium Citrate