||Takahashi N, Boysen G, Li F, Li Y, Swenberg JA
||Oliver Smithies on 2/10/2009
|Volume : Pages
||71 : 266 - 271
||Endogenous creatinine clearance (Ccr) is widely accepted as an estimate of
glomerular filtration rate (GFR), the best overall biomarker of kidney function.
However, current common methods of measuring creatinine are not sensitive
enough for mouse plasma. Accordingly, we here report a new method of measuring
creatinine by liquid chromatography tandem mass spectrometry (LC-MS/MS) using
deuterated [2H3]-creatinine as an internal standard. The assay requires 10 ll or
less of plasma or urine, and is eight times more sensitive than high-performance
liquid chromatography. The reproducibility of the assay of replicates is
approximately 710%. The plasma creatinine levels of wild type male C57BL/6J mice
obtained by LC-MS/ MS are 0.07670.002mg/dl (n¼65). To estimate daily urinary
creatinine excretion for calculating Ccr, we collected urine from mice housed in
metabolic cages, and combined this with washes from the cage internal surfaces.
Creatinine in the wash varies from 4 to 67% of the total daily urinary
creatinine excretion (typicallyB400 lg/day). Ccr obtained by LC-MS/MS was 329717
ll/min, which is indistinguishable from GFR measured by using fluorescein
isothiocyanate-inulin. The LC-MS/MS method is sensitive, specific, simple, fast,
and inexpensive; it is suitable for estimating GFR in conscious mice or other
small animals. As it allows repeated measurements in the same animals, it
facilitates detection of subtle differences or changes in renal function.