Endothelin excretion during ketoacidosis does not correlate with tubular dysfunction.

Urinary excretion of endothelin was measured by radioimmunoassay in children with diabetes mellitus during severe ketoacidosis and 12 days later when blood pH and blood glucose concentrations were normal. Metabolically stable diabetic children served as controls. Results from apparently healthy children without diabetes mellitus were used as normal values. Renal tubular injury was evaluated by the urinary excretion of the proximal tubular marker alpha 1-microglobulin and the distal tubular marker Tamm-Horsfall protein (THP). During ketoacidosis we detected a decreased glomerular filtration rate associated with highly significant changes in the excretion of alpha 1-microglobulin, indicating proximal tubular damage, and THP, suggesting disturbance of cells of the ascending loop of Henle. The daily excretion of endothelin was unaltered but the ratio of endothelin/creatinine or endothelin excretion/creatinine clearance were significantly enhanced. In conclusion, we could demonstrate that, despite a proximal and distal tubular cell dysfunction, endothelin excretion is not elevated during ketoacidosis. The increased endothelin excretion when related to creatinine clearance may be a consequence of disturbed proximal tubular function or dysfunction of the renal medulla.