Variable Factors affecting the Neonatal Kidney Size

Lee, Hyun Ju; Cha, Jung Hwa; Lee, Soo Jeong; Lee, Sun Wha; Park, Eun Ae

Abstract

OBJECTIVE
There are reports that a history of low birth weight, and accordingly, a small kidney could be a risk factor for hypertension and end-stage renal disease in older age. We looked for factors that have an influence on the kidney size to make guidelines for follow up and early detection of renal diseases.
METHODS
From April 2003 to October 2004, we studied the kidney size of neonates, who had an abdominal ultrasound done within two weeks of life. We measured the kidney length and anterior-posterior (AP) diameter and compared the values with each patient's gestational age, birth weight, height, body surface area (BSA), percentile, blood pressure, laboratory findings and various neonatal diseases.
RESULTS
The kidney length and AP diameter had a good correlation with the patient's gestational age, birth weight, height and BSA. The kidney size was larger in the appropriate for gestational age (AGA) than in the small for gestational age (SGA) group in full term neonates. The kidney size did not have a correlation with systolic and diastolic blood pressure, laboratory findings, such as hemoglobin or hematocrit, and various diseases, except congenital heart disease, which had a weak correlation with kidney size.
CONCLUSION
Neonates with early gestational period, low birth weight, small height and BSA tend to have a small kidney. Also SGA patients, especially symmetrical type, tend to have a small kidney. So we recommend high risk neonates to be followed up for early detection of hypertension and renal diseases.