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Abnormal urinary acidification in infants with hydronephrosis
J Chandar1, C Abitbol, M Novak
1Department of Pediatrics, University of Miami School of Medicine/Jackson Memorial Medical Center, FL 33101, USA.
Insights
Infants with hydronephrosis show impaired urinary acidification, leading to metabolic acidosis. This defect in net acid excretion affects both unilateral and bilateral cases, highlighting a kidney function issue in dilated urinary tracts.
Area of Science:
- Pediatric Nephrology
- Urology
- Renal Physiology
Background:
- Dilated urinary tract disorders, including reflux and obstruction, are associated with distal renal tubular abnormalities.
- Understanding urinary acidification defects is crucial for managing infants with hydronephrosis.
Purpose of the Study:
- To investigate patterns of urinary acidification in infants with varying degrees of hydronephrosis.
- To compare acid excretion in infants with hydronephrosis versus controls with secondary metabolic acidosis.
Main Methods:
- Prospective study of three infant groups: hydronephrosis with acidosis (IA), hydronephrosis without acidosis (IB), and controls with diarrhea (II).
- Measurements included serum electrolytes, creatinine, urine pH, urinary titratable acidity, ammonium (NH4) excretion, and net acid excretion (NAE) via titrimetry.
Main Results:
- Infants with hydronephrosis exhibited reduced urinary buffering capacity and low NAE, even when acidotic.
- Both titratable acid and NH4 excretion were deficient in hydronephrosis patients compared to controls.
- Metabolic acidosis occurred similarly in unilateral and bilateral hydronephrosis, irrespective of severity.
Conclusions:
- Confirms a defect in distal urinary acidification in infants with hydronephrosis (unilateral or bilateral).
- Infant immaturity and endogenous acid load may contribute to metabolic acidosis in unilateral hydronephrosis.
Abstract:
Distal renal tubular abnormalities have been observed in patients with dilated urinary tract disorders. The present study was undertaken to look for patterns in urinary acidification in infants with varying degrees of hydronephrosis due to either reflux or obstruction and occurring as unilateral or bilateral disease. Three groups of infants (mean age 3.7+/-3.8 months) were studied prospectively. Groups IA and IB included patients with hydronephrosis who were acidotic and non-acidotic, respectively. Group II served as controls and consisted of patients with diarrhea and secondary metabolic acidosis with no known renal disease. Serum electrolytes, creatinine, and urine pH were measured in all patients. Urinary titratable acidity, ammonium (NH4), and net acid excretion (NAE) were measured by the titrimetric method. Infants with hydronephrosis demonstrated lower urinary buffering capacity, reflected in low NAE in the face of acidosis. Deficiencies were noted in both titratable acid and NH4 excretion compared with control infants. Acidosis was as common in unilateral as in bilateral disease, regardless of severity score. These data confirm a defect in distal urinary acidification in infants with hydronephrosis, whether unilateral or bilateral. Immaturity and endogenous acid load may play a significant role in the manifestation of metabolic acidosis with unilateral disease.