The fractional excretion of uric acid is an index of renal ability to excrete (clear) uric acid and represents the percent of filtered urate to reach the urine.
fractional excretion of uric acid (FEUA) in percent =
= (100% * (((urine uric acid in mg/dL) / (plasma uric acid in mg/dL)) / ((urine creatinine in mg/dL) / (plasma creatinine in mg/dL))))
Testing can be performed on a spot urine sample. Specimens should be collected prior to starting therapy.
Interpretation:
• An increase in FEUA is often associated with uricosuria and serum hypouricemia.
• A decrease in FEUA may be associated with serum hyperuricemia.
Condition
Increased FEUA
Decreased FEUA
volume status
expansion (SIADH, other)
depletion (with prerenal azotemia)
renal disease
diabetic nephropathy
other disease
gout
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