Magnesium and Platelet Function Testing

Magnesium has built up the reputation of a 'natural calcium antagonist'. However, the exact effect of magnesium on coagulation and more specifically on platelet function is still disputed. An important discrepancy between in vivo and in vitro studies exists. Magnesium has thus been reported to antagonize platelets in some studies, and to stimulate platelets in other studies. Current evidence seems to point in the direction of a general antagonization of aggregation and coagulation. Intravenous magnesium is often administered in pre-eclampsia as seizure prophylaxis. Therapeutic regimens usually consist of an intravenously administered loading dose (2-3 grams) and a maintenance infusion, targeting a plasma level of 2-3 mmol/L. Therapeutic drug monitoring is needed, as magnesium toxicity is an important concern.