<prompt> Causes of Hypocalcemia in a child areDiGeorge syndromeHypoparathyroidismMagnesium deficiencyAll of above  <response>: Causes of hypocalcemia HypoparathyroidismDiGeorge syndrome PTH receptor defect pseudohypoparathyroidismMagnesium deficiency Exogenous organic phosphate excess Vit D difecidecien 