Kidney Size, Blood Pressure, Microalbuminuria and Glomerular Filtration Should Be Monitored in the Follow-Up of Preterm Infants

Introduction: Children born prematurely grow up with risk of kidney damage. Objectives: To study blood pressure, glomerular filtration, microalbuminuria/creatininuria ratio and kidney size in preterm infants to determine the prevalence of high blood pressure and alterations in other variables. To associate kidney size with the variables studied. Methods: Prospective, cross-sectional study. Population: preterm infants and a group of full term newborns (controls). Period: July/2017 to July/2018. Inclusion: outpatient premature infants with gestational age <= 32 weeks, birth weight 1,500 g, >= 1 to <= 7 years. The following factors were studied: perinatal data, blood pressure and renal function at the time of ultrasound control. Length, antero-posterior and transverse diameters were measured in both kidneys through sonography. Relative length, absolute volume, relative volume and predictive volume were calculated. A descriptive and inferential analysis was carried out. Results: 43 premature infants and 21 controls were studied, their mean age being 4.42 and 3.9 years, respectively. Systolic hypertension was observed in 21% of cases and diastolic hypertension in 37%; altered glomcrular filtration was found in 74%; altered microalbuminuria/creatinine ratio was determined in 80%. The mean length was shorter than controls in 53% of preterm infants and it was lower than the Rosenbaum mean values in 86%. The mean volume was lower than controls in 58% of preterm infant as well as the predictive volume in 45% of them. Conclusion: Children born prematurely, aged between 1 and 7, presented a high frequency of high blood pressure, glomerular filtration and pathological microalbuminuria/creatinine ratio, as well as lengths and volumes different from the reference values. These could be considered risk factors for kidney health in preterm infants.