The Relation between Breast Milk Sodium to Potassium Ratio and Maternal Report of a Milk Supply Concern

Abstract

We report here that among exclusively breastfeeding mothers at day 7 postpartum, those with milk supply concerns were significantly more likely to exhibit biochemical evidence of less progress toward mature lactation (elevated milk Na:K). Furthermore, elevated milk Na:K was predictive of early weaning.

Comparison of Inductively Coupled Plasma Optical Emission Spectrometry with an Ion Selective Electrode to Determine Sodium and Potassium Levels in Human Milk

“…It has been reported that human milk sodium drops from 60 mM to 10 mM between days 1 and 5 postpartum, this precipitous drop reflects tight junction closure [ 2 ]. Delayed onset of secretory activation is established as a risk factor for poor lactation outcomes [ 3 ] with high sodium concentrations at day 7 considered a risk factor for the cessation of breastfeeding [ 4 ].…”

“…This is mirrored by changes in the human milk transcriptome during this period and is therefore considered more accurate than using time postpartum to define lactation stage [ 5 ]. Changes in the Na:K ratio form a continuum over the first week postpartum, with a high Na:K ratio on day 7 (>0.8) [ 4 ] indicative of suboptimal milk supply or feeding problems and consequently a higher risk of breastfeeding cessation. An elevated ratio on day 7 is associated with 3.3 times greater odds of stopping breastfeeding in mothers reporting concerns about milk supply [ 4 ].…”

“…A high Na:K ratio is also indicative of the increased mammary epithelial permeability associated with breast inflammation, breast engorgement or mastitis [ 4 , 6 , 7 , 8 ]. The Na:K ratio is viewed as superior to sodium alone as it negates the variation found in proportions of aqueous and fat layers of the milk which occur when different sampling methods are used.…”

“…Immediate measurement of HM sodium and potassium concentrations would be advantageous in situations of suspected delayed secretory activation and mammary infection allowing rapid intervention. Currently these components are measured with instruments such as flame photometry [ 4 ], atomic absorption spectroscopy [ 7 ], ion chromatography, inductively coupled plasma optical emission spectroscopy (ICP-OES), and inductively coupled plasma mass spectroscopy (ICP-MS). All of these techniques, which require hazardous chemicals, laboratory facilities, and highly skilled operators, are not immediate and are also costly.…”

Hands-On or Hands-Off When First Milk Matters Most?

“…Biomarkers: by 72 hours, compositional changes in colostrum, reflecting paracellular junction closure directly relate to early, frequent, and effective colostrum removal and are predictors of the adequacy of future production and infant intake. [19][20][21] Nomograms predicting weight loss per hour of life can help determine infants at the extremes for excessive weight loss. As early as 6 hours, weight loss differentials for term infants at risk for excessive weight loss (>10%) are evident.…”