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Oral acetazolamide in the assessment of (urine-blood) PCO2
U Alon1, S Hellerstein, B A Warady
1Department of Pediatric Nephrology, Children's Mercy Hospital, University of Missouri-Kansas City 64108.
Insights
Acetazolamide offers a viable alternative to sodium bicarbonate for assessing urine-blood PCO2 difference in children, showing comparable results despite altering blood pH and bicarbonate levels.
Area of Science:
- Pediatric Nephrology
- Clinical Chemistry
- Acid-Base Balance
Background:
- Assessing urine-blood PCO2 difference is crucial in pediatric kidney function evaluation.
- Oral sodium bicarbonate (NaHCO3) is commonly used but often poorly tolerated by children.
- Alternative methods for urine alkalinization are needed for accurate pediatric studies.
Purpose of the Study:
- To compare the efficacy of oral acetazolamide versus oral sodium bicarbonate (NaHCO3) in assessing urine-blood PCO2 difference in children.
- To evaluate the impact of acetazolamide on blood and urine parameters compared to NaHCO3.
- To determine if acetazolamide can serve as a suitable alternative to NaHCO3 for this diagnostic procedure.
Main Methods:
- A study involving 14 children and adolescents with normal or impaired kidney function.
- Each participant underwent two separate assessments: one with oral sodium bicarbonate (2.5 mEq/kg) and one with acetazolamide (17 ± 2 mg/kg).
- Standard protocols were followed to measure blood pH, serum bicarbonate, urine PCO2, plasma PCO2, and urine-blood PCO2 difference.
Main Results:
- Acetazolamide administration led to significantly lower blood pH and serum bicarbonate levels compared to NaHCO3.
- Acetazolamide resulted in a significantly higher urine PCO2 compared to NaHCO3.
- No significant differences were observed between the two methods regarding their effects on urinary pH, HCO3- concentration, plasma PCO2, and the urine-blood PCO2 difference.
Conclusions:
- Acetazolamide and sodium bicarbonate (NaHCO3) demonstrate good linear correlation in their effects on urine PCO2 and urine-blood PCO2 difference.
- Acetazolamide is a potentially effective alternative to oral NaHCO3 for assessing urine-blood PCO2 difference in pediatric patients.
- Further research may confirm acetazolamide's utility, especially in cases where NaHCO3 is not well-tolerated.
Abstract:
Urine-blood (U-B)Pco2 difference in children is usually assessed following urine alkalinization with oral sodium bicarbonate (NaHCO3). Since oral NaHCO3 is often poorly tolerated by children, we compared oral acetazolamide with oral NaHCO3 in a study of (U-B)Pco2. In the first phase of the study 14 children and adolescents aged 11.1 +/- 3.7 years (mean +/- SD) were studied. Eight participants had normal kidney function and 6 had disturbed distal acidification capacity. Each child was studied twice, once with oral NaHCO3 (2.5 mEq/kg) and once with acetazolamide (17 +/- 2 mg/kg). All studies were performed according to the standard protocol. Acetazolamide administration resulted in a lower blood pH than NaHCO3 (7.30 +/- 0.03 vs 7.38 +/- 0.06, P less than 0.001) and a lower serum bicarbonate (HCO3-) concentration (25.1 +/- 2.2 mEq/l vs 27.5 +/- 2.1 mEq/l, P less than 0.025). Acetazolamide also resulted in a higher urine Pco2 (81.9 +/- 26.2 mm Hg vs 71.6 +/- 18.2 mm Hg) than NaHCO3 (P less than 0.025). No significant differences between acetazolamide and NaHCO3 were observed with respect to their effects on urinary pH and HCO3- concentration, plasma Pco2 and (U-B)Pco2. Good linear correlations were found between the effects of acetazolamide and NaHCO3 on urine Pco2 (r = 0.878, P less than 0.001), and on (U-B)Pco2 (r = 0.795, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)