Refractory rickets due to Fanconi's Syndrome secondary to Wilson's disease

Renal tubular disorders are an important cause of refractory rickets. Wilson's disease, an inherited disorder of copper metabolism has varied presentations. We present a case of refractory rickets due to Fanconi's syndrome attributable to Wilson's disease. An adolescent girl presented with pain in the hip and knee joints and a knock-knee deformity since six years. She had received multiple doses of cholecalciferol with little improvement. There was no history of seizures, polyuria, jaundice, intake of drugs, or similar complaints in the family. Examination revealed a severely short stature with widening of the wrist joint and genu valgum. Examination of the central nervous system (CNS) was normal. Skeletal radiographs showed features suggestive of rickets at the hip and knee joints. Routine biochemistry was normal, 25-hydroxyvitamin D [25(OH)D] was adequate (57.1 ng/dL), with normal corrected calcium (9.24 mg/dL), low phosphate (2.76 mg/dL), elevated bone-specific alkaline phosphatase, and normal renal functions. Twenty-four-hour urine revealed phosphaturia, kaliuresis, and glucosuria with normal blood sugars and aminoaciduria. Blood gas analysis revealed normal anion gap metabolic acidosis with a urine pH of 7. Ammonium chloride (NH4CL) challenge test revealed proximal tubular acidosis. A search for causes revealed Kayser-Fleischer rings. The diagnosis of Wilson's disease was confirmed by low serum ceruloplasmin levels (6.5 mg/dL; normal: 18-35 mg/dL) with high 24-hour urine copper levels (433 mcg; normal: 20-50 mcg). She was started on a replacement of alkali, phosphate, calcium, and vitamin D, with zinc acetate for Wilson's disease. Rickets as a presenting feature of Wilson's disease has been reported rarely. Recognition of this entity is important, as treatment of the primary condition may improve tubular function as well.