Tear urea nitrogen and creatinine levels in renal patients.

Tear and blood urea nitrogen, creatinine, and glucose levels were quantitatively analyzed by an enzymatic method in 30 normal patients and in 10 patients with end stage renal disease. The tear and blood samples collected from the end stage renal patients before and after hemodialysis showed that the change in urea nitrogen and creatinine levels in the tears correlated with the change in blood urea nitrogen and creatinine. Tear samples may serve as an alternative, less invasive indicator of serum metabolites in renal patients.