Abstract
2 sisters, 3 (sib I) and 7 (sib II) years old, from consanguineous and normal parents, presented with active rickets, skeletal deformities and alopecia totalis after years of vitamin (vit) D2 therapy (50,000 IU/d). Representative levels in serum for sib I and II, respectively, were Ca, mg/dl: 9.8, 8.9; P, mg/dl: 4.0, 2.9; 25-OHD, ng/ml: 47, 42 (normal 27±5); parathyroid hormone (PTH), μl-eq/L: 42, 44 (normal = < 40); 1,25(0H)aD3, pg/ml, was >300 (normal = 46) in both sibs. Both sibs had a calcemic response to PTH: ↑ Ca by 1.3 and 2.1 mg/d1 and normal renal responses (P and CAMP) to PTH. The TRP in both was 77-80%. The mean balances, mg/d, in sib I for Ca was -55 and for P-95, while in sib II the value for Ca was -140 and for P-190. 1,25(OH)aD3 treatment at doses of .04 and .06 μg/kg/d (.50μg and .75μg/d) failed to reverse the biochemical abnormalities or heal the ricketic lesions.
These 2 sibs have a new inborn error of vit D metabolism marked by intestinal end-organ unresponsiveness to supranormal levels of 1,25(OH)2D3, endogenously synthesized, leading to malabsorption of Ca and P and rickets. Also, both sibs have hyporesponsiveness to 1,25(OH)2D3 at bone in view of normo-calcemia despite extremely high 1,25(OH)2D3 and slightly elevated PTH levels in serum.
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Rosen, J., Fleischman, A., Finberg, L. et al. 338 A NEW TYPE OF RICKETS: UNRESPONSIVENESS OF BONE AND INTESTINE TO HIGH LEVELS OF ENDOGENOUSLY SYNTHESIZED 1,25-DIHYDROXYVITAMIN D3 [1,25(0H)2D3]. Pediatr Res 12 (Suppl 4), 420 (1978). https://doi.org/10.1203/00006450-197804001-00343
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DOI: https://doi.org/10.1203/00006450-197804001-00343