50 - Epidemiology of early onset dysnatremia in extremely preterm infants

Poster Number: 50
Publication Number: 50.1731

Background: Early onset dysnatremia(EOD) is common in extremely preterm infants(EPI).Numerous factors influence serum sodium(Na) concentrations in EPI including Na and fluid intake.Dysnatremia includes both hyponatremia(hypoNa)(Na < 135mmol/L) and hypernatremia(hyperNa)(Na>145mmol/L).Limited data is available on the epidemiology of dysnatremia in EPI

Objective: The objective of this study was to examine the demographics,clinical profile and short-term outcomes of EPI developing EOD

Design/Methods: Single centre retrospective cohort study of 100 EPI( < 28 wk gestation).Data from day(D)1 to 14 after birth was collected.Mild,moderate(mod) and severe(sev) hypoNa were defined as Na130-134,Na126-129 and Na < 125mmol/L,respectively.Mild, mod and severe hyperNa were defined as Na146-149,Na150-159 and Na>160mmol/L,respectively. Acute kidney injury(AKI) was defined based on neonatal adaptation of the kidney disease improving global outcomes(KDIGO) criteria.Descriptive analysis was performed for continuous and frequencies/proportions for categorical variables.Comparison of proportions was done using chi-square test.

Results: Prevalence of EOD in EPI was 98%;85% had hypoNa and 50% had hyperNa.77% had mild,37% had mod,and 18% had sev hypoNa;and 71% had mild,29% had mod,and 2% had sev hyperNa.One third of the population(37%) had both hypo and hyperNa,with 75% of infants with hyperNa in the first week(peak on D3),going on to develop hypoNa within the first 2 weeks after birth(peak on D8).(Fig 1) Demographic features between hypoNa vs hyperNa groups were comparable.There was 17% higher proportion of extremely low birth weight infants(ELBW) in the hyperNa group(p=0.0276).Mortality was higher in hyperNa group (12% vs 5%)(p=0.1396).(Table 1) AKI incidence based on serum creatinine was 14% each; and based on urine output was 27% and 26% respectively in the hypoNa and hyperNa groups.Serum creatinine was checked more often following hyperNa (57% vs 34%).While hypoNa was treated by increase in Na intake,hyperNa was treated by increasing fluid intake.(Table 2)

Conclusion(s): Early onset hypoNa is more common than hyperNa in EPI.HypoNa may follow hyperNa suggesting that electrolytes must be closely monitored in EPI.The demographic, clinical profile and short-term outcome of EPI with both types of dysnatremias is similar,except for higher ELBW infants and higher mortality in the hyperNa group,indicating they were likely sicker and therefore led to higher proportion of kidney function check,and fluid intake adjustment in that group.Prospective studies looking at EOD may help delineate epidemiology, understand pathophysiology and prevent EOD in EPI