Los Angeles County-University of Southern California Medical Center clinical pathology case conference: extreme hypermagnesemia in a neonate.

A preterm male infant born at 33 weeks of gestation developed respiratory depression and apnea at approximately 20 h after birth. Laboratory tests indicated severe hypermagnesemia, acidosis, and hypercalcemia. Cord blood and maternal blood concentrations of magnesium were normal. The effects and possible causes of hypermagnesemia are reviewed. The infant recovered with treatment, although the etiology of his hypermagnesemia remains unknown.