Increased PTH is seen in all except:
(C) Thyrotoxicosis/None # 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-(OH)D3 by damaged kidneys; inhibition of the renal hydroxylase involved in the conversion of 25-(OH)D3 to the more active metabolite 1,25-(OH)D3 by the high levels of phosphorus; and reduced intestinal absorption of calcium because of low levels of 1,25-(OH)2 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.
Primary & secondary hyperparathyroidism
Lithium induced hyperparathyroidism
Thyrotoxicosis
Familial hypocalciuric hypercalcemia
Miscellaneous