Renal phosphate and bicarbonate wastage in diabetic keto-acidosis

A subject with juvenile diabetes mellitus showed inappropriately elevated urine pH and mild bicarbonate leakage during systemic acidosis with blood pH 7.24 and plasma bicarbonate 12 meq/l. The lowered renal bicarbonate reabsorptive threshold was accompanied also by tubular phosphate wastage of profound degree, expressed either as per cent T.R.P. or\(\frac{{T_m P}}{{G.F.}}\) Both tubular abnormalities were seen to disappear spontaneously during insulin therapy as ketonuria ceased, but recurred as ketonuria returned in later collections. Subsequent formal intravenous bicarbinate loading studies in the absence of keto-acidosis demonstrated normal values for ‘threshold’ reabsorption as well as TmHCO3. The data suggest a temporary inhibition of tubular bicarbonate and phosphate reabsorption during ketosis possibly due to competition with beta-hydroxybutyrate and/or aceto-acetate for a shared anion reabsorptive pathway.