Serum calcium concentrations and incidence of hypocalcemia in infants with moderate or severe hypoxic-ischemic encephalopathy: Effect of therapeutic hypothermia

• After a hypoxic-ischemic insult, a widespread influx of Ca2 + into the cells might lower serum Ca2 + levels.
• Therapeutic hypothermia decreases this influx and may improve Ca2 + homeostasis.
• This historical cohort analysis demonstrated that hypothermia was associated with less hypocalcemia despite lower Ca2 + intakes.
• Introduction of therapeutic hypothermia therapy improved Ca2 + homeostasis.

BackgroundHypocalcemia is a common morbidity in asphyxiated infants. Therapeutic hypothermia (TH), the standard of care for infants with moderate and severe hypoxic-ischemic encephalopathy (HIE), promotes neuroprotection by several mechanisms including a decrease in intracellular calcium (Ca2 +) influx which may improve serum Ca2 + levels and homeostasis.AimsTo evaluate the impact of TH on Ca2 + homeostasis.Study designHistorical, retrospective cohort analysis.SubjectsInfants with moderate or severe HIE admitted to the hospital with ≤ 24 hours of age, gestational age ≥ 36 weeks, and birth weight ≥ 1800 g, before (pre-TH) and after (post-TH) TH was implemented.Outcome measuresMinimum and maximum serum levels of ionized Ca2 + (iCa2 +) and magnesium (Mg), Ca2 + and Mg intakes, and incidence of hypo/hypercalcemia during the first week of life.ResultsA total of 67 infants were included: 29 pre-TH and 38 post-TH. Minimum iCa2 +levels were significantly lower in the pre-TH group; some infants required Ca2 + boluses infusions. In the post-TH group, a significantly lower intake of Ca2 + was necessary to maintain normal Ca2 + levels and no infant required boluses. The incidence of hypocalcemia was higher in the pre-TH group with a statistically significant difference on day 2 of life (18 vs 0%; p = 0.01).ConclusionsAfter the implementation of TH, iCa2 + levels were within normal ranges despite lower Ca2 + intakes. A lower incidence of hypocalcemia was observed during cooling. Our findings support the hypothesis that TH improves Ca2 + homeostasis in HIE infants.