ESPN 51th Annual Meeting

ESPN 2018


 
Maximum urinary pCO2 determination after stimulation with acetazolamide and bicarbonate in pediatric age. A review.
MARIA ISABEL LUIS YANEZ 1 ISIDRO PACHECO LOPEZ 1 PEDRO ARANGO SANCHO 2 PATRICIA TEJERA CARREñO 1 FATIMA FRAGA BILBAO 3 ALMA SERRANO 4 MARIA VICTORIA MAGALLANES 4 VICTOR MANUEL GARCIA NIETO 1

1- SECCION DE NEFROLOGIA PEDIATRICA DEL HOSPITAL UNIVERSITARIO NUESTRA SEñORA DE CANDELARIA, SANTA CRUZ DE TENERIFE
2- UNIDAD DE NEFROLOGIA PEDIATRICA DEL HOSPITAL SANT JOAN DE DEU, BARCELONA
3- UNIDAD DE NEFROLOGIA PEDIATRICA DEL HOSPITAL UNIVERSITARIO DE CANARIAS, SANTA CRUZ DE TENERIFE
4- SERVICIO DE NEFROLOGIA PEDIATRICA DEL CENTRO MEDICO NACIONAL LA RAZA, MEXICO DF
 
Introduction:

Study of the capacity of distal renal tubular acidification by determining the urinary pCO2 after a simultaneous administration with half of the usual doses of acetazolamide and sodium bicarbonate.

Material and methods:

We reviewed the tests in which the maximum urinary pCO2 in pediatric age was determined by a simultaneous administration of sodium bicarbonate and acetazolamide. These tests were performed in the Functional Test Unit of our hospital from 1996 to the present (n=172). The doses administered orally were 2 mEq/kg of sodium bicarbonate and 500 mg/1.73 m2 of acetazolamide. In order for the test to be rated as normal, it was considered that urinary pCO2 should be greater than 70 mmHg (Kozeny GA et al). At the same time, to considered valid, the concentration of CO3H- urinary should be higher than 80 mEq/l (Laski ME,Kurtzman NA).

Results:

Thirteen tests were not valid. The age of children with valid acidification tests was 7.96±3.99 years (range:0.8-14) (n=159;79V,80M). Seventeen patients (10.7%) showed a defect in acidification capacity. Their diagnoses were distal type 1 RTA (n=5), renal lithiasis and prelitiasis (n=3), acute pyelonephritis (n=3) and other causes (n=6). In normal tests (UpCO2 >70 mmHg) (n=142) a direct correlation of urinary pCO2 was observed both with urine bicarbonate (r=0.57;p<0.001) and age (r=0.21;p=0.01). Likewise, statistically significant differences in the value of urinary pCO2 were observed when distributing the sample according to the different groups formed from bicarbonate levels (ANOVA,p<0.001). No side effects were observed.

Conclusions:

Our original method of performing the pCO2 test with half dose of acetazolamide and sodium bicarbonate is valid and has no side effects. There is a statistically significant direct relationship between maximum urinary pCO2 and urine bicarbonate levels. It is necessary to check if the normal minimum values of maximum urinary pCO2 are different according to the age of the patients and urine bicarbonate levels.