Increased osmolality of breast milk with therapeutic additives

Abstract

Aim: To evaluate the changes in the osmolality of expressed breast milk (EBM) after the addition of seven additives and four proprietary fortifiers commonly used during neonatal intensive care.

Methods: The osmolality of 5 ml EBM was measured with increasing doses of 6% NaCl, caffeine, sodium ironedetate, folic acid, and multivitamin drops. Sodium acid phosphate and chloral hydrate were added to 8 ml EBM, and the fortifiers were added to standard volumes of EBM. Dose-effect curves were plotted, and the volume of milk that must be added to the above additives to maintain osmolality below 400 mOsm/kg was calculated.

Results: The osmolality of the pure additives ranged from 242 to 951 mOsm/kg. There was a significant increase in the osmolality of EBM with increasing doses of all additives except caffeine. The osmolality of EBM with many additives in clinically used dosages potentially exceeded 400 mOsm/kg. The greatest increase occurred with sodium ironedetate syrup, where the osmolality of EBM increased to 951.57 (25.36) mOsm/kg. Proprietary fortifiers increased the osmolality of EBM to a maximum of 395 mOsm/kg.

Conclusion: Routine additives can significantly increase the osmolality of EBM to levels that exceed current guidelines for premature infant feeding. A simple guide for clinical use is presented, which indicates the amount of milk required as diluent if hyperosmolality is to be avoided.

Figure 1

Osmolality of expressed breast milk with increasing doses of nutritional additives showing least squares linear regression and 95% confidence intervals.

Figure 2

Amount of expressed breast milk required as solvent to maintain osmolality below 400 mOsm/kg.