Renal tubular dysfunction with nephrocalcinosis in a patient with beta thalassemia minor

Thalassemia is a hereditary anemia resulting from defect in hemoglobin production. Beta thalassemia is due to impaired production of beta globin chains, leading to a relative excess of alpha globin chains. The term beta thalassemia minor is used to describe heterozygotes, who carry one normal beta globin allele and one beta thalassemic allele. The vast majority of these patients are asymptomatic. However, a variety of renal tubular abnormalities including hypercalciuria, hypo­magnesemia with renal magnesium wasting, decreased tubular absorption of phosphorus, hypo­uricemia with renal uric acid wasting, renal glycosuria and tubular proteinuria have been described even in patients with beta thalassemia minor. We here in report a 24-year old female patient who was found to have thalassemia minor and nephrocalcinosis with evidence of renal tubular dysfunction. Investigations revealed normal renal function, hypercalciuria, reduced tubular reabsorption of phos­phorus, hypomagnesemia and renal magnesium wasting. Screening for aminoaciduria was found to be negative. An acid loading test revealed normal urinary acidification. Ultrasonogram of the abdomen revealed nephrocalcinosis and splenomegaly. Detailed work up for anemia showed normal white cell and platelet count while peripheral smear showed microcytic hypochromic anemia with few target cells. Hemoglobin electrophoresis revealed hemoglobin A of 92%, hemoglobin A2 of 6.2% and hemo­globin F of 1.8% consistent with beta thalassemia minor. Her parental screening was normal. A diag­nosis of beta thalassemia minor with renal tubular dysfunction was made and the patient was started on thiazide diuretics to reduce hypercalciuria and advised regular follow-up.