<prompt> Increased PTH is seen in all except:Primary secondary hyperparathyroidismLithium induced hyperparathyroidismThyrotoxicosisFamilial hypocalciuric hypercalcemia  <response>: C ThyrotoxicosisNone Chronic renal failure results in phosphate retention and hyperphosphatemia. Hyperphosphatemia, in turn, induces secondary hyperparathyroidism because phosphate appears to regulate parathyroid hormone secretion directly. Hypocalcemia develops as the levels of vitamin D 1,25-dihydroxyvitamin D3 1,25-2 D3 fall because of decreased conversion from the vitamin D metabolite 25-OHD3 by damaged kidneys; inhibition of the renal hydroxylase involved in the conversion of 25-OHD3 to the more active metabolite 1,25-OHD3 by the high levels of phosphorus; and reduced intestinal absorption of calcium because of low levels of 1,25-OH2 D3 . Thyrotoxicosis - since thyroid hormone an increase tissue responsiveness to catacholamine and they can stimulate PTH secretion. Lithium - S.calcium S. Phosphate f Urine calcium excretion - PTH Familial hypocalciuric hypercalcaemia - Most cases are associated with loss of function mutation in ASR genu, which exceedscalcium sending receptor expressed in parathyroid and leads to high level of PTH and the positive hypercalcemia. 