Particularités épidémiologiques, cliniques et évolutives de l’acidose tubulaire distale primitive chez l’enfant tunisien

Introduction

The distal renal tubular acidosis of children is characterized by hyperchloremic metabolic acidosis with normal anion gap, hypokalemia, hypercalciuria and nephrocalcinosis. It is secondary to the inability of alpha intercalar cells of the distal tubule to acidify urine of genetic origin.

Objective

To analyse the epidemiological aspects of distal tubular acidosis in Tunisia and study its evolutionary profile.

Patients and methods

We conducted a retrospective descriptive study involving 44 patients followed at the paediatrics department of the Charles Nicolle Hospital in Tunis for 28 years (1991–2018).

Results

The most common discovery circumstances were growth retardation (88.6%), dehydration (56.8%), ployuro-polydipsic syndrome (47.7%), vomiting (40.9%) and nephrocalcinosis (38.6%). Growth retardation was found in 52.3% of patients. Dehydration was diagnosed in 59.1% of patients on the first exam. Polyuria was constant with an average diuresis of 8 cc/kg/h. All patients had the complete form of distal renal tubular acidosis with an average alkaline reserve of 11.1 mmol/L. Nephocalcinosis was found in 77.3% associated with nepholithiasis in 22.7%. Twenty-four patients had sensorineural deafness, nine of whom had ATP6V1B1/2p13 mutation. The ATP6V0A4/7q33-34 mutation was present in two patients. We used a high alkaline treatment dose with an average maintenance dose of 8.17 mmol/kg/24 hours. In the long term, stunting persisted in 34% of patients. The mean of creatinine's clearance at the last evaluation was 89.38 mL/min/1.73 m² SC with stage 2 of chronic kidney disease in 50% of patients.

Conclusion

Distal renal tubular acidosis has long been considered a benign pathology but is responsible for a progressive decline in GFD. Adequate metabolic control is needed to stabilize kidney function.