Plasma Ionized Calcium, Phosphate and Magnesium in Preterm and Small for Gestational Age Infants

Abstract

Blood concentrations of ionized calcium, phosphate and magnesium were determined on days 1, 3 and 5 in 32 preterm infants, appropriate for gestational age, and 25 small for gestational age infants. The results were compared with those of a reference group of 31 fullterm newborns. Preterm infants had lower mean ionized calcium levels than the reference population. Ionized calcium levels were positively correlated with gestational age and postnatal age. The sickest infants had the lowest calcium levels. Intrauterine growth retardation did not seem to influence the calcium levels. Small for gestational age infants had lower phosphate values than the reference group and the values correlated with the degree of growth retardation the first day. Magnesium concentrations increased with time and did not differ significantly between the study groups and the reference group. Magnesium values did not correlate with calcium or phosphate values.

Serum total magnesium and ionized calcium concentrations in asphyxiated term newborn infants with hypoxic‐ischaemic encephalopathy

“…In infants with severe HIE, we found decreased mean concentrations of total Mg in umbilical cord blood. Hypomagnesaemia after birth asphyxia has also been described earlier (10,11,13,16). The causes of the low total Mg concentrations in umbilical cord blood serum are not clear, but the duration and severity of hypoxicischaemic insult seems to influence the serum total Mg concentration (13).…”

“…The causes of the low total Mg concentrations in umbilical cord blood serum are not clear, but the duration and severity of hypoxicischaemic insult seems to influence the serum total Mg concentration (13). It is possible that different changes in total Mg concentration are seen following prolonged or versus acute hypoxia, explaining also hypomagnesaemia found in newborns with intrauterine growth retardation (10,11). Caddell and Reed suggested that total Mg determination during acidosis may give a falsely elevated value and may mask a true total Mg deficiency which can be diagnosed only after homeostasis is re-established (19).…”

“…Data about normal concentrations of Mg and Ca 2 in umbilical cord blood and venous blood have been published (9)(10)(11)(12)(13), but data about changes of Mg and Ca 2 concentrations described in asphyxiated infants are controversial (9)(10)(11)(12)(13)(14)(15)(16).…”

Preterm male infants need more initial respiratory and circulatory support than female infants

“…In the present study, male infants had lower ionized calcium during the first 4 d than females. Blood levels of ionized calcium are related to severity of illness in critically ill patients and in newborn infants (27). There were no gender differences in maximum potassium or sodium levels during the first 4 d. High potassium levels in preterm infants have been associated with low systemic blood flow and the development of large intraventricular haemorrhages (28,29).…”

Ionized magnesium and gestational age

“…20 We found that lower gestational age was associated with higher IMg levels, which did not decrease during the first days of life in the majority of infants with gestational age <32 week. Although some investigators 12, 21 classed post conceptual age and postnatal age as unique factors contributing to variations in neonatal Mg levels, Nelson et al 22 found no correlation between the neonatal Mg levels and gestational age. However, none of these studies investigated the impact of blood pH on the IMg in relationship with gestational age.…”