Uremia with low serum creatinine-an entity produced by marked creatinine secretion.

Two patients are presented who were uremic requiring dialysis despite steady state serum creatinine levels (Cr) of 4.0 and 4.4 mg percent. Their blood urea nitrogen/creatinine (BUN/Cr) ratios of 54 and 44 were shown to be due to excessive creatinine secretion and urea reabsorption. Evaluation of serum creatinine alone may occasionally give misleading information regarding the level of renal function. If clinical evidence of uremia is present while serum creatinine value is relatively low, measurement of glomerular filtration rate (GFR) by Na-iothalamate 125I (OIT) or inulin is essential.