TIME-COURSE AND FUNCTIONAL CORRELATES OF POSTTRANSPLANT ALUMINUM ELIMINATION

Urinary excretion of aluminium after a successful transplant can rever se pre-transplant aluminium intoxication. We have evaluated the time c ourse of urinary aluminium excretion and its correlation with several parameters of renal function and mineral metabolism in 49 patients (33 men and 16 women) with a wide range of pre-transplant serum aluminium concentrations, performing sequential determinations at pre-transplan t time and at 7, 30, 60, and 90 post-transplant days. Mean serum alumi nium at pre-transplant was 54.5 +/- 46.8 mu g/l decreasing progressive ly to 28.7 +/- 24.4 mu g/l at 90 days (P < 0.0002), paralleling the de crease in serum creatinine. Urinary aluminium decreased from 63.0 +/- 77.9 to 52.4 +/- 55.9 mu g/l at 90 days (P < 0.0001). The maximum urin ary aluminium/ creatinine was 1.8 +/- 2.7 at 7 days and was associated with the greatest fractional excretion of sodium (4.7 +/- 5.1%), and the lowest tubular reabsorption of phosphate ( 55.7 +/- 25.1%). The fr actional excretion of aluminium was also greatest at day 7 (1.11 +/- 0 .9%) when serum creatinine was still elevated (3.6 +/- 2.3 mg/dl). At each period of time after transplantation fractional excretion of alum inium was similar in all patients despite disparate serum aluminium co ncentrations. Fractional excretion of aluminium was highest in those p atients who developed post-Tx acute tubular necrosis (0.7 +/- 0.5 vs 1 .5 +/- 1.0%, P = 0.008). We found a direct positive correlation (r = 0 .43; P < 0.002) between urinary aluminium and urinary phosphate. Basal levels and sequential changes in serum PTH, calcium, and phosphate di d not correlated with fractional excretion of aluminium. These finding s suggest: (i) urinary aluminium remains elevated during prolonged per iods after transplant and is probably a marker of pre-transplant tissu e aluminium accumulation; (ii) post-transplant fractional excretion of aluminium seems to correlated positively with other evidences of rena l tubular dysfunction. Early post-transplant tubular malfunction could significantly enhance urinary aluminium elimination.