The patellar reflex in preeclamptic women with subtherapeutic and therapeutic serum magnesium levels.

The normalization of hyperreflexia has been proposed by some authorities as an indicator of adequate seizure prophylaxis in preeclamptic women receiving magnesium sulfate. To test this hypothesis the patellar reflex response was measured with a quantitative technique in 20 preeclamptic patients during their progression from subtherapeutic to therapeutic serum levels of magnesium. Patients meeting selected criteria for hyperreflexia demonstrated a 46% decrease in their reflex response. Those without initial hyperreflexia failed to demonstrate a significant decrease.