A 72-year-old man is recently found to have hypocalcemia and Osteomalacia is suspected based on the decrease in the cortical bone thickness and osteopenia seen on x-rays. Which of the following is the most likely mechanism of the resistance to the effects of vitamin D?
excess parathyroid hormone secretion
insufficient parathyroid hormone secretion
defective receptors for 25(OH) vitamin D
defective receptors for 1,25OH2 vitamin D
Deficient or defective 1,25(OH)2 vitamin D receptors will result in vitamin D resistance. Parathyroid hormone levels increase secondary to decreased vitamin D effect. The 1(OH) vitamin D is an intermediate metabolite.
Immunology and Rheumatology