• CIR(s) = citrate infusion rate(s);
  • iCa = ionized calcium;
  • iMg = ionized magnesium;
  • iPTH = intact PTH;
  • Pi = inorganic phosphorus;
  • PTH = parathyroid hormone;
  • WB:AC = whole blood to anticoagulant;
  • WBFR(s) = whole-blood flow rate(s)

BACKGROUND: Although plateletpheresis procedures are generally well tolerated, the clinical and metabolic consequences associated with rapid infusion of up to 10 g of citrate are underappreciated, and a comprehensive description of these events is not available.

STUDY DESIGN AND METHODS: Clinical and laboratory changes were studied in seven healthy donors undergoing three 90-minute plateletpheresis procedures each, at continuous, fixed citrate infusion rates of 1.1, 1.4, and 1.6 mg per kg per minute.

RESULTS: Serum citrate levels increased markedly with increasing citrate infusion rates and did not achieve a stable plateau. As citrate infusion rates increased, the total volume processed and platelet yields also increased, but donor symptoms became more severe. Ionized calcium (iCa) and ionized magnesium (iMg) concentrations decreased markedly, by 33 and 39 percent below baseline, respectively, at a citrate rate of 1.6 mg per kg per minute. Intact parathyroid hormone levels were higher at 30 minutes than at later time points, despite progressive decreases in iCa and iMg. Urine citrate, calcium, magnesium, sodium, and potassium concentrations and urine pH values increased markedly during all procedures.

CONCLUSION: Marked, progressive increases in serum citrate levels occur during plateletpheresis, accompanied by symptomatic decreases in iCa and iMg, with significantly increased renal excretion of calcium, magnesium, and citrate.