Ans. is 'c' i.e., Hypoparathyroidism o This child has :- i) Hypocalcemia ii) Hyperphosphatemia in) Normal PTH levels o Option b & d can be ruled out because :- i) In Vitamin D deficiency :- serum calcium is normal or slightly reduced (7.5 -slightly reduced; and parathormone levels are increased. ii) hypoxic ischemic encephalopathy is not related to calcium and phosphate me o Now, we are left with Pseudohypoparathyroidism and hypoparathyroidism both hyperphosphatemia. o In Pseudohypoparathyroidism, there is increased concentration of parathyroid most of the times. Thus, this option is also excluded. o Coming to hypoparathyroidism: As the name suggests, PTH is low in hypoparathyroidism. But, sometimes PTH may be in normal range (10-60 Pg/ml) and this is inappropriately normal PTH. However it is generally believed that 'Normal' levels of PTH in a patient with hypocalcemia indicate 'inappropriately normal PTH' and relative Hypoparathyroidism should always be considered as the initial diagnosis. `Serum PTH levels should be related to the concurrent serum calcium. High PTH is the normal response to hypocalcemia and therefore 'normal' PTH in a patient with Hypocalcemia indicates relative Hypoparathyroidism' -Practical Algorithms in Pediatric Endocrinology' by Hochberg (2007)/71. 'Because normally hypocalemia is a potent stimulus for secretion of PTH, patients with intact parathyroid gland function should be expected to have high circulating levels of PTH, during hypocalcemic episodes. Low levels of serum PTH and in some assays even inapropriately 'normal' levels despite hypocalcemia should prompt consideration of various form of hypoparathyroidism' - Principles and Practice of Endocrinology & Metabolism' by Beeker.