A 10-year-old boy presents with short stature, round facies, and shortened fourth and fifth metacarpals. Vital signs show BP 102/68 mmHg, HR 78/min, RR 18/min, temperature 37°C. Laboratory studies reveal calcium 7.2 mg/dL (hypocalcemia), phosphate 5.8 mg/dL (hyperphosphatemia), PTH 156 pg/mL (elevated), and normal TSH. Physical examination shows no thyroid abnormalities. Which of the following best explains his condition?
- A)Parathyroid adenoma with autonomous secretion
- B)Loss of parafollicular C cells
- C)Defective Gs protein signaling causing end organ resistance to PTHGABARITO
- D)Activating mutation of the RET proto oncogene
- E)Vitamin D intoxication
Explicação
This patient has pseudohypoparathyroidism, classically associated with Albright hereditary osteodystrophy. The target organs are resistant to PTH because of defective Gs protein signaling, so calcium remains low and phosphate remains high despite elevated PTH.... Ver explicação completa e trilha adaptativa →