Serum creatinine is an inadequate screening test for renal failure in ischemic stroke patients

Serum creatinine (SCr) level is the most commonly used screening test for renal function, but its concentration is affected by factors other than glomerular filtration rate (GFR). We hypothesized that SCr would underestimate the degree of renal failure in ischemic stroke patients.

We conducted a prospective study of 273 patients admitted to our institution for ischemic stroke within a year. GFR was calculated using the Cockcroft-Gault formula (CG). Patients were grouped according to the SCr with stages of renal failure according to CG values.

Of the 273 patients studied, 231 had normal SCr. Of this group 46.8% (108), 24.7% (57) and 4 (1.7%) had mild, moderate and severe renal failure according to GFR estimation. Among patients with normal SCr, abnormal CG values were identified in 86.2% (150) > or = 65 years old, 33.3% (19) <65 years old, 69% (89) in men and 78.4% (80) in women. An SCr greater than 1.7 mg/dl had only a sensitivity of 14.7%.

This study documents the substantial prevalence of significantly abnormal renal function among patients with normal-range SCr. Routine estimation of GFR be preferred to SCr as a screening method for the early detection of renal impairment in stroke patients.