This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
Increased PTH is seen in all except: 
Select and explain. 
A. Primary & secondary hyperparathyroidism, B. Lithium induced hyperparathyroidism, C. Thyrotoxicosis, D. Familial hypocalciuric hypercalcemia
C: Thyrotoxicosis
Answer: C: Thyrotoxicosis 
Explanation: (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.