A urinary calcium-citrate index for the evaluation of nephrolithiasis

Kidney Int. 1986 Jul;30(1):85-90. doi: 10.1038/ki.1986.155.


We have performed a multivariate analysis of urine abnormalities in patients with calcium oxalate nephrolithiasis, in which effects of gender were also considered. The characteristic of patients that most clearly sets them apart from normal people is a high level of urine calcium for any given level of urine citrate. Other urine measurements cannot improve upon the separation between patients and normals provided by urine calcium and citrate, and their abnormal relationship to each other. Normal women have higher urine citrate and lower urine calcium than normal men or patients of either sex; normal men differ from stone forming men only moderately. Direct measurements of supersaturation are not helpful in distinguishing between patients and normals, once calcium and citrate have been considered. From our analysis, we have derived a new index for evaluating the significance of urine calcium and citrate levels that seems to offer a better basis for clinical diagnosis than criteria presently in use.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Calcium / urine*
  • Citrates / urine*
  • Citric Acid
  • Female
  • Humans
  • Kidney Calculi / etiology
  • Kidney Calculi / therapy
  • Kidney Calculi / urine*
  • Male
  • Oxalates / urine
  • Oxalic Acid
  • Regression Analysis
  • Sex Factors
  • Sodium / urine
  • Uric Acid / urine


  • Citrates
  • Oxalates
  • Uric Acid
  • Citric Acid
  • Oxalic Acid
  • Sodium
  • Calcium