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Renal cation excretion in the hypocalcemic premature human neonate
Insights
In premature neonates, sodium excretion strongly correlates with calcium, magnesium, and phosphorus excretion. High sodium intake, not calcium intake, is linked to lower serum calcium levels in these infants.
Area of Science:
- Neonatal Physiology
- Renal Mineral Metabolism
Background:
- Premature neonates often experience electrolyte imbalances.
- Understanding mineral excretion patterns is crucial for managing hypocalcemia in preterm infants.
Purpose of the Study:
- To investigate the interrelationship of urinary sodium, calcium, magnesium, and phosphorus excretion in hypocalcemic premature neonates.
- To determine the influence of sodium and calcium intake on these excretion patterns and serum calcium levels.
Main Methods:
- Studied 22 hypocalcemic premature neonates (mean gestational age 31.7 wk).
- Measured urinary excretion of sodium, calcium, magnesium, and phosphorus over 84 hours.
- Analyzed correlations between cation intake, excretion, and serum calcium concentration.
Main Results:
- Strong positive correlations were found between sodium excretion and the excretion of calcium (r=0.85), magnesium (r=0.76), and phosphorus (r=0.94).
- Sodium intake significantly correlated with sodium, calcium, magnesium, and phosphorus excretion.
- Serum calcium concentration was negatively related to total sodium intake (r=-0.71) but independent of calcium intake.
Conclusions:
- Urinary sodium excretion is closely linked to calcium, magnesium, and phosphorus excretion in premature infants.
- Sodium intake appears to be a more critical factor than calcium intake in influencing serum calcium levels in this population.
Abstract:
We describe the interrelationship of the urinary excretion of sodium, calcium, magnesium, and phosphorus in 22 hypocalcemic premature neonates whose mean gestational age was 31.7 wk. Strong relationships between sodium excretion and calcium excretion (r = 0.85), sodium excretion and magnesium excretion (r = 0.76), sodium excretion and phosphorus excretion (r = 0.94) were demonstrated. Sodium intake during the 84-hr study period ranged from 2.9 to 34.5 mEq/kg and calcium intake during the same period ranged from 0 to 152.3 mg of elemental calcium per kg. The intakes of the other cations were negligible. All variables but phosphorus excretion (r = -0.55) were independent of calcium intake whereas sodium excretion (r = 0.76), calcium excretion (r = 0.72) magnesium excretion (r = 0.62), and phosphorus excretion (r = 0.53) were all correlated with sodium intake. Serum calcium concentration at the end of the study was unrelated to total calcium intake during the 84-hr study period, whereas it was negatively related to total sodium intake (r = -0.71).