Rickets secondary to distal renal tubular acidosis: A case report

Abstract

Background: Rickets that does not improve with conventional treatment warrants evaluation for non-nutritional causes. Distal renal tubular acidosis (dRTA) can impair bone mineralization through persistent metabolic acidosis. Case summary: A 6-year-old boy born to consanguineous parents presented with three years of progressive bilateral leg bowing and poor growth, followed by polyuria and polydipsia. Treatment for rickets and hypothyroidism had not improved his symptoms. His height was 93 cm (−4.5 SDS), with marked leg deformity and muscle wasting. Investigations showed hyperchloremic metabolic acidosis (arterial pH 7.17, bicarbonate 8.2 mmol/L, chloride 122 mmol/L), hypokalemia (2.9 mmol/L), and an inappropriately alkaline urine pH of 7.0. He also had hypophosphatemia, elevated alkaline phosphatase (2502 U/L), and hypercalciuria. Radiographs showed metaphyseal fraying, cupping, and splaying; renal ultrasonography revealed bilateral medullary nephrocalcinosis. These findings supported a diagnosis of rickets secondary to dRTA. Alkali therapy, potassium, calcium, and vitamin D supplementation were initiated. Conclusion: In a child with treatment-resistant rickets, growth failure, polyuria, and hypokalemia, dRTA should be considered. Early diagnosis permits correction of acidosis and may help prevent further skeletal and renal complications. [J Assoc Clin Endocrinol Diabetol Bangladesh, 2026;5(Suppl 1): S76]