[Primary distal renal tubular acidosis in children in the south of Tunisia: study of 15 cases]

ABSTRACT

Primary distal renal tubular acidosis in children [RTA] is characterized by metabolic acidosis due to defect in urinary excretion of hydrogen [H+] in the distal tubular. To report the epidemiological, clinical, therapeutic and evolutionary of distal RTA in our patients. Patients and methods: We conducted a retrospective study of all cases of distal RTA collected in the department of pediatrics of Hedi Chaker University hospital in the south of Tunisia, during a period of 23 years [1988-2010]. We studied the epidemiological, clinical, biological, evolutionary and therapeutic data. During the study period 15 cases of distal RTA were collected. The average age was 6 months [1 month -2 years]. Most common presenting symptoms were vomiting [8cases], failure to thrive [4cases], lack of appetite, polyuria-polydipsia syndrome [1case] and urinary infection [2cases]. The clinical examination showed staturoponderal delay [9 cases], dehydration [6 cases], signs of rickets [3 cases] and polyuria [10 cases]. Biological data showed high urine pH in the presence of metabolic acidosis in 11 cases, hypokalaemia in 10 cases and hypercalciuria in all cases. Urine acidification test with ammonium chloride was performed in 4 cases, the urinary pH was always higher than 5.5 in all cases. Ammoniuria performed in 9 cases was less than 40mmol/l. Radiological investigation objectified a nephrocalcinosis in fourteen patients and signs of rickets in three cases. Deafness was found in three patients. Genetic study performed in two cases showed mutation of ATP6V1B1 gene. The medical treatment involved an alkali load. Long-term outcome was favorable in 7 cases. The distal renal tubular acidosis is a rare pathology in our country but probably under diagnosed. The clinical gravity of this disease and the risk of evolution towards the terminal renal insufficiency justify an antenatal diagnosis to establish a neonatal management or propose a therapeutic interruption of the pregnancy if the distal RTA is associated with a severe pathology