A 63-year-old man with stage 4 chronic kidney disease presents with progressive diffuse bone pain and muscle weakness. Vital signs: BP 148/92 mmHg, HR 88/min, RR 16/min, temp 37.2°C. Laboratory studies reveal ionized calcium 6.8 mg/dL (low), phosphate 5.2 mg/dL (elevated), PTH 487 pg/mL (markedly elevated), and normal 25-hydroxyvitamin D levels. He denies recent fractures. Which pathophysiologic mechanism best explains his endocrine abnormality?
- A)Autonomous PTH secretion by parathyroid adenoma
- B)Reduced phosphate excretion and decreased calcitriol productionGABARITO
- C)Suppressing antibodies against the TSH receptor
- D)Increased renal conversion of vitamin D to calcitriol
- E)End organ resistance to parathyroid hormone
Explicação
Chronic kidney disease causes phosphate retention and impaired 1 alpha hydroxylation of vitamin D, leading to low calcitriol and reduced intestinal calcium absorption. The resulting hypocalcemia stimulates compensatory parathyroid hormone secretion, producing ... Ver explicação completa e trilha adaptativa →