Prospective surveillance confirms prior retrospective observations that D- patients do not appear to risk D alloimmunization after receiving D+ apheresis PLTs.

Hypocalcemic toxicity, because of return of citrate anion to the donor, is the major toxicity of apheresis platelet donation. Oral calcium carbonate, given prophylactically at the start of donation, has shown limited ability to alleviate this toxicity. We examined whether repeated prophylactic doses of calcium carbonate, or of a liquid preparation containing calcium citrate, calcium phosphate, and vitamin D 3 , would be more effective at preventing symptoms of hypocalcemic toxicity. Symptoms were reported by 48% of donors who received no prophylaxis and 60% of donors who received 1000 mg of oral calcium carbonate at the start of, and every 20 minutes during, donation (P 5 0.711). Only 19.2% of donors who received the liquid preparation (1000 mg calcium, 1000 IU vitamin D 3 ) reported symptoms (P 5 0.040 versus no prophylaxis, P 5 0.039 versus calcium carbonate). This difference was not because of gender, weight, age, or blood volume of the donor. Neither calcium preparation prevented a measurable fall in plasma ionized calcium during donation. We conclude that liquid calcium citrate/calcium phosphate/vitamin D 3 provides effective prophylaxis against hypocalcemic toxicity during platelet donation, however it does not prevent a fall in plasma ionized calcium. K E Y W O R D Sblood donor, paresthesia, plateletpheresis, side effects | I NT ROD UCTI ONHypocalcemic toxicity is a common adverse effect of apheresis platelet donation. [1][2][3] It is caused by the return to the donor of plasma carrying a citrate-based anticoagulant, and may limit the blood flow rate and component yield during collection procedures. 3,4 Prophylactic administration of 1-2 g of oral calcium carbonate has been shown to have a distinct but modest effect on plasma ionized calcium ([Ca 21 ]) during platelet donation with only very modest effects on overall symptom development in the donors. 5,6 Gastrointestinal absorption and bioavailability of calcium carbonate is relatively limited compared to some other calcium salts such as calcium citrate, 7-9 and little is known about the effects of repetitive prophylactic dosing of calcium during platelet donation. We therefore undertook to examine alternative approaches to oral prophylaxis for hypocalcemic toxicity in apheresis platelet donation.