Use of urinary parameters in the diagnosis of total acute renal artery occlusion.

Limited attention has been paid to the composition of the small amounts of urine that are frequently produced by patients with acute renal failure (ARF) of vascular origin. We have investigated the value of basic urinary parameters in the early diagnosis of total or partial acute renal artery occlusion (ARAO). We have reviewed the records of 30 patients with ARF: group 1 (n = 10) had total ARAO; group 2 (n = 10) had unilateral ARAO with a contralateral functioning kidney, and group 3 (n = 10) had hemodynamically mediated ARF subsequent to a major vascular abdominal surgical procedure, without arterial thrombosis. Serum sodium, potassium, urea, creatinine and osmolality, as well as urinary sodium, potassium, urea, creatinine and osmolality, were determined by standard techniques, and the fractional excretion of sodium (FENa) was calculated. Serum parameters were similar in all groups. Urinary sodium and FENa were higher in group 1 than in the other groups (p < 0.01), while urinary potassium was lower (p < 0.05). Urinary urea (p < 0.01) and osmolality (p < 0.05) were higher in group 2 than in the other groups, revealing a prerenal pattern in some cases. Serum and urinary concentrations of sodium, urea and creatinine and osmolality were similar in group 1, while respective serum and urinary concentrations and osmolality were different from each other in the other groups. Analysis of urine provides a useful diagnostic tool in ARF of vascular origin. When urinary concentrations of sodium, urea and creatinine are similar to those in serum and FENa approaches 100%, the strong likelihood of total ARAO should be acknowledged, and renal arteriography is mandatory.