A 61-year-old woman presents with progressive fatigue, constipation, and diffuse bone pain for 3 months. Vital signs: BP 138/88, HR 92, RR 16, Temp 37°C, SpO2 98%. Hand radiographs demonstrate subperiosteal bone resorption. Laboratory studies reveal serum calcium 11.2 mg/dL (normal 8.5–10.2), PTH 187 pg/mL (normal 15–65), and normal 25-hydroxyvitamin D level. She denies recent weight loss. Which pathophysiologic mechanism best explains her skeletal findings?
- A)Parathyroid hormone induced osteoblast expression of RANKLGABARITO
- B)Inhibition of renal 1 alpha hydroxylase by parathyroid hormone
- C)Decreased osteoblast activity from low thyroid hormone
- D)Direct osteoclast stimulation by parathyroid hormone
- E)Calcitonin mediated activation of osteoclasts
Explicação
Parathyroid hormone does not directly activate osteoclasts. Instead, it stimulates osteoblasts to increase expression of RANKL, which then activates osteoclasts and promotes bone resorption. Chronic excess PTH can therefore produce osteitis fibrosa cystica wit... Ver explicação completa e trilha adaptativa →