VITAMIN-D RESISTANT RICKETS WITH ALOPECIA - A FORM OF END ORGAN RESISTANCE TO 1,25 DIHYDROXY VITAMIN-D

A 4 yr old girl presented with severe clinical and radiological rickets and alopecia since the age of 1 yr. Laboratory studies revealed: hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, abnormally low intestinal Ca absorption, and markedly elevated circulating 1,25(OH)2D3 [dihydroxyvitamin D3] levels. A normal calcemic response to parathyroid extract was obtained. Treatment attempts with vitamin D2, 1.alpha.(OH)D3 and 1,25(OH)2D3 were totally ineffective. Intestinal resistance to the action of 1,25(OH)2D3 appeared well established in this case. Refractoriness of bone to this hormone seems less certain. From this new entity of vitamin D resistant rickets due to end organ unresponsiveness, 6 cases have been reported in the literature. However, only 2 have enough resemblance to this case, to constitute a distinct and well defined nosologic subunit. The molecular basis of this disorder(s) remains to be elucidated.