Introduction: Hypothyroidism has been reported to affect renal function and structure. However, the association of hypothyroidism with distal renal tubular acidosis (dRTA) is rarely reported in children.
Case presentation: We present a 6-year-boy with Down syndrome admitted in our department due to vomiting, weakness, polyuria, polydipsia, irritability and weight loss in the last few weeks. Investigations revealed features of hypokalemia, metabolic acidosis and alkaline urine consistent with dTRA. Abdominal ultrasound found nephrocalcinosis. In addition, Antithyroid peroxidase antibodies were positive, suggesting an autoimmune background for the pathogenesis of the tubular dysfunction. Treatment for dRTA and hypothyroidism was started and symptomatic improve was noticed.
Conclusion: dRTA should be excluded in children with autoimmune disorders who develop weakness, polyuria, polydipsia or growth failure. Early diagnosis would reduce long-term complications.
Keywords: Down syndrome; Hashimoto thyroiditis; distal renal tubular acidosis; nephrocalcinosis.