Equis ISSN 2398-2977

Urine: creatinine clearance

Contributor(s): Annalisa Barrelet

Overview

  • Creatinine is a non-protein nitrogenous substance liberated during muscle metabolizm.
  • Daily production is remarkably constant and related to muscle mass.
  • The rate of excretions is almost entirely proportional to glomerular filtration in that only minmal (<10%) tubular re-absorption or acute excretion occurs.
  • The concentration of creatinine   Urine: creatinine  in the urine reflects the amount of substance filtered as well as the volume of water removed by the nephron.
  • The ratio of urine   Urine: creatinine  to serum creatinine   Blood: biochemistry - creatinine  provides indirect information about both glomerular filtration and tubular function.
  • Creatinine clearance (C) is a more sensitive indicatior of renal function than BUN or serum creatinine.
  • The formula for calculation of creatinine clearance is:
    • C=UvUc / Pc (where Uv is urine volume, Uc is urine concentration and Pc is plasma concentration).

Sampling

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Tests

Technique (intrinsic) limitations

  • Enzymatic methods for measurement of creatinine are needed (rather than Jaffe method) to obtain sufficient accuracy.

Result Data

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Further Reading


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