A 2 year old boy has vitamin D refractory rickets. Investigations show serum calcium 9 mg/dl. Phosphate 2.4 mg dl, alkaline phosphate 1040 parathyroid hormone and bicarbonate levels are normal. The most probable diagnosis is –
Distal renal tubular acidosis
Hypophosphatemic rickets.
Vitamin D dependent rickets
Proximal renal tubular acidosis