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Updated: Jul 27, 2026
Estimation of Nephron Number in Whole Kidney using the Acid Maceration Method
Published on: May 22, 2019
Renal parameters during infancy
K P Mehta1, S R Karnik, A Sathe
1Department of Pediatrics, Jaslok Hospital and Research Centre, Bombay.
Insights
Neonatal renal function shows immature acidification, leading to mild metabolic acidosis and hyperchloremia. High renin and aldosterone levels are also normal in infants up to six months old.
Area of Science:
- Pediatric Nephrology
- Neonatal Physiology
Background:
- Renal function in neonates differs significantly from adults.
- Understanding these early changes is crucial for accurate assessment.
Purpose of the Study:
- To prospectively evaluate key renal parameters in healthy term neonates.
- To track these parameters through the first year of life.
Main Methods:
- Prospective study of 48 full-term neonates.
- Repeated measurements at 6 and 12 months for 15 infants.
- Assessed serum creatinine, uric acid, blood gases, electrolytes, plasma renin activity, and aldosterone.
- Renal size evaluated by ultrasonography.
Main Results:
- Elevated serum creatinine and uric acid at birth, normalizing by 6 months.
- Low blood pH and bicarbonate at birth, reaching adult levels by 12 months.
- High chloride levels at birth, normalizing by 6 months.
- Persistently high plasma renin activity and elevated plasma aldosterone at birth, decreasing by 12 months.
- Renal length and volume within normal American standards.
Conclusions:
- Mild metabolic acidosis and hyperchloremia in neonates are due to immature renal acidification.
- High renin and aldosterone levels indicate partial distal tubule nonresponsiveness, a normal finding.
- Elevated neonatal serum creatinine and uric acid are expected and should be considered when assessing renal function.
Abstract:
In a prospective study we estimated common renal parameters in 48 full term normal neonates, of which 15 were also tested at 6 months and 12 months of age. The mean levels of serum creatinine, were high at birth (0.73 mg/dl) but normal for age at 6 and 12 months; uric acid followed a similar trend. The blood pH and bicarbonate were low at birth (7.28 and 20.36 mEq/L, respectively) reached normal adult values by 12 months; chloride levels were high at birth (110 +/- 5 mEq/L) and normal at 6 months. The plasma renin activity was higher than normal all throughout the first year (27.1, 416.8, 64.8 ng/ml/hr by RIA). Plasma aldosterone values were high at birth (1387.5 pg/ml) and reached normal level (301.6) at 12 months. Renal length and volume as assessed by ultrasonography compared well with American standards. Urinary constituents were variable due to breast feeding up to 6 months and varied diet during the weaning period. This study shows that mild metabolic acidosis and hyperchloremia due to immaturity of renal acidification mechanism and high renin and aldosterone levels due to partial nonresponsiveness of distal tubules are normal variables in babies from birth to 6 months. The levels of serum creatinine and uric acid are high at birth and in assessing renal functions this should be borne in mind.
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