Hyperchloremic Acidosis in Early Diagnosis of Renal Allograft Rejection

Hyperchloremic renal tubular acidosis has been observed to occur in a surprisingly high percentage of episodes of rejection in patients who have had cadaver renal allografts. Impairment of hydrogen ion excretion is the commonest defect, although multiple defects in tubular function have also been encountered. In those rejection episodes that were not associated with the development of hyperchloremia, the pattern of acid excretion resembled that associated with simple loss of functioning nephrons. In over half of the cases hyperchloremia became evident before rejection became definable by conventional criteria (sometimes even 1 to 2 weeks before). Elevation in serum chloride in patients who have had cadaver renal allografts is a valuable and reliable early sign of rejection. Furthermore, it may indicate smouldering rejection activity even when serum creatinine has come back to prerejection levels during reversal of the episode. Reestablishment of normochloremia may be a good prognostic guide to the efficacy of treatment of a rejection episode, provided allowance is made for the effect of exogenous sodium bicarbonate, which may also have been deemed necessary.