Match each patient's clinical presentation and laboratory profile to the most likely underlying pathophysiologic mechanism.
- A 68-year-old man with a long smoking history presents with confusion and a central lung mass. Laboratory studies show serum calcium 13.5 mg/dL, phosphorus 2.1 mg/dL, and intact PTH 9 pg/mL (normal 15-65 pg/mL).Secretion of a peptide homologous to parathyroid hormone
- A 45-year-old woman is evaluated for a history of recurrent renal colic. Laboratory studies show serum calcium 11.2 mg/dL, phosphorus 2.4 mg/dL, and intact PTH 88 pg/mL.Autonomous overproduction of parathyroid hormone
- A 24-year-old man is found to have asymptomatic hypercalcemia on routine insurance screening. Laboratory studies show serum calcium 11.4 mg/dL, intact PTH 42 pg/mL, and 24-hour urine calcium of 35 mg/day.Inactivating mutation in the calcium-sensing receptor
- A 32-year-old African American woman presents with persistent dry cough, erythema nodosum, and bilateral facial nerve palsy. Laboratory studies show serum calcium 11.9 mg/dL, phosphorus 4.4 mg/dL, and intact PTH 12 pg/mL.Ectopic extra-renal 1-alpha-hydroxylase activity
- A 60-year-old housebound woman presents with diffuse, dull bone pain and proximal muscle weakness. Laboratory studies show serum calcium 7.8 mg/dL, phosphorus 2.2 mg/dL, intact PTH 145 pg/mL, and elevated alkaline phosphatase.Impaired osteoid mineralization due to severe 25-hydroxyvitamin D deficiency
Cevap
The clinical vignettes represent distinct mechanisms of calcium and phosphorus dysregulation: Humoral hypercalcemia of malignancy (PTHrP), Primary hyperparathyroidism (PTH overproduction), Familial hypocalciuric hypercalcemia (calcium-sensing receptor mutation), Sarcoidosis (ectopic 1-alpha-hydroxylase), and Osteomalacia (Vitamin D deficiency).
Correct matching requires evaluating serum calcium alongside serum phosphorus, intact PTH levels, and key clinical contextual clues to determine whether the metabolic abnormality is PTH-driven, PTH-independent, or a result of a defective receptor set-point.
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Anahtar Kavram
Differential diagnosis of calcium and bone metabolism disorders using paired serum calcium, phosphorus, and parathyroid hormone levels.