Chapter 42: Agents That Affect Bone Mineral Homeostasis
Which of the following drugs is routinely added to calcium supplements and milk for the purpose of preventing rickets in children and osteomalacia in adults?
The 2 forms of vitamin D—cholecalciferol and ergocalciferol— are commonly added to calcium supplements and dairy products. Calcitriol, the active 1,25-dihydroxyvitamin D3 metabolite, would prevent vitamin D deficiency and is available as an oral formulation. However, because it is not subject to the complex mechanisms that regulate endogenous production of active vitamin D metabolites, it is not suitable for widespread use. The answer is A.
A 65-year-old woman presents with chronic intermittent lower back pain for the last 8–10 years. She has spinal curvature. Six months ago back pain and spasms kept her in bed for 2 weeks. Radiographs of her lower back and pelvis showed increased bone density with cortical thickening with a coarse trabecular pattern and a lytic area in the greater trochanter. Which of the following drugs is most useful for the treatment of hypercalcemia in her disease?
This patient has Paget disease, which is characterized by excessive bone resorption, poorly organized bone formation, and hypercalcemia. Bisphosphonates and calcitonin are first-line treatments. Pamidronate is a powerful bisphosphonate used parenterally to treat hypercalcemia. The answer is C.
The active metabolites of vitamin D act through a nuclear receptor to produce which of the following effects?
(A) Decrease the absorption of calcium from bone
(B) Increase PTH formation
(C) Increase renal production of erythropoietin
(D) Increase the absorption of calcium from the GI tract
(E) Lower the serum phosphate concentration
The active metabolites of vitamin D increase serum calcium and phosphate by promoting calcium and phosphate uptake from the GI tract, increasing bone resorption, and decreasing renal excretion of both electrolytes. They inhibit, rather than stimulate, PTH formation. The answer is D.
A 59-year-old female was referred to your clinic for evaluation of osteopenia. She was diagnosed with adult-onset cystic ...