Bartter syndrome a case of secondary hyperaldosteronism
Isabel Manita, Andreia Veloza, Catarina Coelho, Catarina Saraiva, Dolores Passos, Maria Cordeiro, Luísa Raimundo & Jorge Portugal
Introduction: Bartter syndrome represents a set of closely related autosomal recessive renal tubular disorders characterised by hypokalemia, hypochloremia, metabolic alkalosis and hyperreninemia with normal blood pressure. The underlying abnormality results in excessive urinary losses of sodium, chloride and potassium. Bartter syndrome is classified into 3 main clinical variants: neonatal Bartter syndrome, classic syndrome and Gitelman syndrome.
Case report: We present a 19 year-old male caucasian, the only child of a consanguinuos marriage, referred for severe hypokalemia detected during investigation of anemia (spherocytosis). Data concerning pregnancy, delivery and early childhood is not available. There is a history of nocturnal enuresis that lasted until 12 years of age, and of persistent polyuria and polydipsia. Growth and pubertal development were normal. Symptoms such as parestesias, fatigue and spasms were absent.
Laboratorial tests revealed hypokalemia alkalosis, normomagnesiemia, hypercalciuria and hyperaldosteronism. Renal ultrasound did not show alterations. We are waiting for the opportunity to order genetic testing. Other causes of hypokaliemia were excluded such as surreptitious diuretic and laxative abuse, persistent vomiting and diarrhoea.
On the ground of clinical appearance and biochemical data, the Bartter syndrome in classic variant was diagnosed. Good therapeutic effect was achieved using spironolacton, indomethacin and potassium supplementation.
Conclusion: Bartter syndrome is a rare autosomal recessive disorder. Recent molecular diagnosis has revealed that Bartter syndrome results from mutation in 5 distinct genes that affect the function of ion channels of the distal nephron segments. The literature confirms a lack of correlation of genotype and phenotype in this disease.
In this case the authors emphasize the unusual late and asymptomatic presentation.