The lack of influence of long-term potassium citrate and calcium citrate treatment in total body aluminum burden in patients with functioning kidneys

Background: It has been suggested that citrate salts might enhance aluminum (Al) absorption from a normal diet, posing a threat of Al toxicity even in subjects with normal renal function. We have recently reported that in normal subjects and patients with moderate renal failure, short-term treatment with tricalcium dicitrate (Ca3Cit2) does not significantly change urinary and serum Al levels. However, we have not assessed total body Al stores in patients on long-term citrate treatment. Objective: The objective of this study was to ascertain body content of Al non-invasively using the increment in serum and urinary Al following the intravenous administration of deferoxamine (DFO) in patients with kidney stones and osteoporotic women undergoing long-term treatment with potassium citrate (K3Cit) or Ca3Cit2, respectively. Methods: Ten patients with calcium nephrolithiasis and five with osteoporosis who were maintained on potassium citrate (40 mEq/day or more) or calcium citrate 800 mg calcium/day (40 mEq citrate) for 2 to 8 years, respectively, and 16 normal volunteers without a history of regular aluminum-containing antacid use participated in the study. All participants completed the 8 days of study, during which they were maintained on their regular home diet. Urinary Al excretion was measured during a two-day baseline before (Days 5, 6) and for 1 day (Day 7) immediately following a single intravenous dose of DFO (40 mg/kg). Blood for Al was obtained before DFO administration, and at 2, 5 and 24 hours following the start of the infusion. Results: The median 24-hour urinary Al excretion (microgram/day) at baseline versus post-DFO value was 15.9 vs. 44.4 in the normal subjects and 13.3 vs. 35.7 in the patients. These values were all within normal limits and did not change significantly following DFO infusion (p = 0.003 and p = 0.0001, respectively). The median change of 17.1 microgram/day in urinary Al in the normal subjects was not significantly different from the 18.7 micro/day change measured in the patient group (p = 0.30). Similarly, no change in the mean serum Al was detected at any time following the DFO infusion either in the patient or control group (patients 4.1 to 4.3 ng/ml, controls 7.4 to 4.6 ng/ml). Conclusion: The results suggest that abnormal total body retention of Al does not occur during long-term citrate treatment in patients with functioning kidneys.