Fig. 1: Various mechanisms of low sodium content in preterm infants.

Inadequate intake (especially in those with predominantly enteral nutrition), high renal and gastrointestinal losses contribute to low body sodium content. Inadequate sodium supplementation decreases absorption of glucose through the sodium-glucose cotransporter (SGLT-1) resulting in suboptimal stimulation of enteroendocrine cells resulting in low growth factor levels [5]. In addition, poor carbohydrate absorption can lead to intestinal dysbiosis and contribute to poor growth. Supplementation of sodium potentially enhances glucose absorption and stimulates neuroendocrine cells to produce growth factors. Healthy intestinal microbiome and normal sodium content may contribute to better growth in extremely preterm infants.