Neonatal Hypocalcemia: Common, Uncommon, and Rare Etiologies

Abstract

Calcium homeostasis in the neonatal period is a reflection of the transition from placental regulation to hormonal maturation in the newborn. Hypocalcemia occurring within the first 72 hours after birth, termed early-onset hypocalcemia (EOH), is more common and often asymptomatic. Hypocalcemia occurring beyond 72 hours of age is termed late-onset hypocalcemia (LOH). LOH is less common than EOH, and affected patients are more likely to be symptomatic. To prevent and treat hypocalcemia in the newborn, neonatal clinicians should be familiar with the common, uncommon, and rare etiologies of EOH and LOH, as summarized in this review.

The significance of vitamin D in the regulation of bone metabolism in term and premature infants

“…In addition, PTH affects the TC, releasing serum calcium from the bone [45]. In the kidneys, PTH stimulates 1-α-hydroxylase for the synthesis of active vitamin D. However, in premature infants, despite increased PTH synthesis, hypocalce-mia may persist for a long time due to incomplete implementation of its effects, as tissues experience transient resistance to this hormone [46][47][48]. Under normal conditions, bone formation predominates over bone decay, including through the action of PTH, which is aimed at increasing the production of OPG-L on the surface of the OB and suppressing the synthesis of OPG [48,49].…”

“…In response to an increase in calcium levels above normal, CT in the kidneys reduces the absorption of Ca 2+ and P 3and in parallel, reduces intestinal absorption, also has a suppressive effect on osteoclasts and, thereby, reduces bone resorption [50,51]. Premature newborns are characterized by increased secretion of CT due to the need to conserve already reduced calcium stores [46,49,51].…”