Serum-Ionized Calcium in Mexican Protein-Energy Malnourished Children

Abstract

Background Hypocalcemia occurring in children with severe primary protein-energy malnutrition (PEM) has previously been shown to merely reflect a reduction in the protein-bound fraction of serum calcium. On the other hand, ultrafilterable, i.e., nonprotein bound calcium (Ca U), remains unaffected. The aim of the present investigation was to test the hypothesis that in infantile PEM, ionized calcium, which represents the major and physiologically most important component of Ca U, is also kept within a normal concentration, whatever the total serum calcium levels. Methods Three milliliters of peripheral venous blood were obtained on admission and periodically afterward from 18 fasting marasmic infants and 6 children with the edematous form of PEM (kwashiorkor). Ionized calcium was determined in 125 μL aliquots of blood serum with ion-selective electrodes. The measurement of related elements and molecules was carried out with customary laboratory procedures. Results On admission, as well as during the ensuing stages of nutritional recovery, ionized serum calcium exhibited a normal concentration, with the exception of two initial samples. Total calcium, total protein, albumin, and inorganic phosphate concentrations were decreased in a variable degree according to the clinical type, ascending to normal levels during recovery. Conclusions Ionized calcium serum concentration remains within normal limits in severe infantile PEM.