Calcium and phosphor intake in preterm infants: sensitivity and specifity of 6-hour urine samples to detect...

Area of Science:

• Neonatal Medicine
• Pediatric Nephrology
• Clinical Chemistry

Background:

• Mineral homeostasis is crucial for preterm infants.
• Accurate monitoring of calcium (Ca) and phosphate (P) is essential for preterm infant health.
• Current monitoring methods may not be optimal for timely detection of mineral imbalances.

Purpose of the Study:

• To evaluate the predictive accuracy of six-hour (6 h) urine specimens for 24-hour (24 h) mineral homeostasis in preterm infants.
• To determine if short-term urine collection can reliably assess calcium and phosphate balance.
• To establish the sensitivity, specificity, and positive predictive value of 6-hour urine samples.

Main Methods:

• Studied 60 stable preterm infants (gestational age 34 weeks).
• Analyzed urinary Calcium (Ca) and Phosphate (P) concentrations in 6-hour urine specimens.
• Calculated coefficients of variation for Ca and P measurements within 24 hours.
• Defined mineral homeostasis based on 24-hour urinary concentrations (≥1 mmol/l for surplus).

Main Results:

• Six-hour urine samples demonstrated high sensitivity and specificity in predicting calcium deficiency homeostasis (PPV 0.90).
• Urinary phosphate prediction using 6-hour samples also showed high accuracy (PPV 0.80).
• Coefficients of variation for Ca and P in 6-hour samples were 0.42 and 0.41, respectively.

Conclusions:

• Six-hour urine sampling is a precise method for predicting calcium and phosphate deficiency in preterm infants on regular feeding schedules.
• While 6-hour samples are predictive, regular monitoring (twice weekly) is advised to prevent missed diagnoses of mineral deficiency.
• This method offers a practical approach to managing mineral balance in vulnerable preterm populations.