[Calcium decreases urinary oxalate].
The effects of calcium supplementation on urinary oxalate excretion was tested in 9 normal subjects, 4 males and 5 females between 23 and 49 years of age. In a crossover study 800 mg calcium was orally administered as active absorbable algal calcium (AAACa) (A) and calcium carbonate (B), and compared with non-calcium containing placebo (C). Calcium, oxalate, osmolality, creatinine and pH were measured in the first three morning urine samples and Ca/osmolality, Ca/osmolality/body weight, Ca/creatinine and oxalate/osmolality were calculated to correct for urine dilution. Ca x oxalate product was also calculated and Ca oxalate crystal in the sediment was microscopically examined and semiquantitatively estimated as -, +, ++, and +++ expressed as 0, 1, 2 and 3 respectively. Urinary Ca excretion was similar in A and B, but significantly larger than C, regardless of the method of correction for dilution. Urinary oxalate excretion tended to be lower in A than in B and C. Urine pH was similar among all three groups. Ca x oxalate product was higher in C than in A and B. AAACa, unlike calcium carbonate, appeared to decrease urinary oxalate excretion and Ca x oxalate product more efficiently than Ca carbonate, suggesting a possibility of inhibiting the formation of Ca x oxalate kidney stones. Formation of calcium oxalate was also tested in vitro by adding oxalate to urine samples and aqueous calcium solution.
Ohgitani
S
S
Division of Laboratory and Research, National Sanatorium Hyogo Chuo Hospital.
Fujita
T
T
D000284:Administration, Oral; D000328:Adult; D002118:Calcium / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002119:Calcium Carbonate / Q000008:administration & dosage / Q000493:pharmacokinetics; D002129:Calcium Oxalate / Q000652:urine; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D010070:Oxalates / Q000652:urine*
D010070:Oxalates; D002129:Calcium Oxalate; D002119:Calcium Carbonate; D002118:Calcium