Healing of rickets during vitamin D therapy despite defective vitamin D receptors in two siblings with vitamin D-dependent rickets type II.

We report the healing of severe rickets despite hypocalcemia in two siblings with absent vitamin D receptors; long periods of treatment with excessive doses of vitamin D led to relative hypoparathyroidism and a return to normal of calcium metabolism during calcitriol treatment. This finding suggests that some other regulating factor may substitute for the defective vitamin D receptor.