Sodium Intake Requirements for Preterm Neonates

Abstract

It is widely accepted that sodium is an essential nutritional electrolyte and its deficiency is associated with neurological sequelae and poor growth. The provision of an adequate sodium intake to preterm neonates is hampered by the technical difficulty in clinically assessing total body sodium content. As addressed in this review, there is a lack of consensus on the definition of hyponatremia early in life, but there is no evidence that it should deviate from the widely accepted normative data for adult subjects. A low urinary sodium content is accepted by many as reflecting total body sodium deficiency, yet spot urinary sodium measurements are of questionable clinical value. The hormonal regulation of sodium homeostasis is here reviewed and the mechanism accounting for sodium deficiency-induced growth impairment in preterm infants addressed. Lastly, we provide evidence-based gestational and postnatal age-dependent recommendations for the provision of adequate sodium intake to preterm neonates.

Risk Factors and Effects of Severe Late-Onset Hyponatremia on Long-Term Growth of Prematurely Born Infants

“…3 ). A causal relationship between sodium deficiency and impaired growth was suggested previously [ 11 ], and LOH of premature infants could reportedly influence extrauterine growth retardation [ 4 ]. In previous reports, the duration of hyponatremia could impair growth during the neonatal period, and delayed supplementation of sodium could partially restore growth.…”

Physiological Approach to Sodium Supplementation in Preterm Infants

“…Finally, spot urine sodium concentration is dependent on circadian cycle, urine flow rate, and dietary and fluid consumption and thus may not reflect a continuous pattern of renal sodium excretion. 28 However, in contrast to older children and adults, there is typically a consistent pattern of provision of diet and fluid to preterm infants, ameliorating some of this concern.…”

Salt need needs investigation

“…Many preterm (about 10 % of babies) and some full-term babies are at risk of hyponatraemia and receive Na supplementation to ensure proper growth and neurological and cognitive development (31,(84)(85)(86)(87) . The severity of the obligatory neonatal dehydration and Na loss predicts the Na content of the diet we will compose in childhood and possibly beyond (36)(37)(38)88) (Fig.…”

“…In fact, it may be that the consequent increase in dietary Na of such children (aged 10-15 years) is unaccompanied by a preference for the taste of salt per se (37) (but see Liem (89) ), a known dissociation (80,89,96) . Finally, in the adolescent growth spurt, Na intake outstrips the intake of energy content, other macronutrients and electrolytes, together suggesting a unique developmental or maturational requirement (39,40,(84)(85)(86)97,98) .…”