Match each of the following patient laboratory profiles to the most likely underlying pathophysiologic mechanism.
(Reference ranges: Serum Calcium: 8.4-10.2 mg/dL; Intact PTH: 10-65 pg/mL; Phosphorus: 2.5-4.5 mg/dL; 24-hour urine calcium: 100-300 mg/day).
- Serum Calcium: 11.2 mg/dL, Intact PTH: 55 pg/mL, 24-hr urine calcium: 45 mg/dayInactivating mutation of the calcium-sensing receptor (CaSR)
- Serum Calcium: 11.8 mg/dL, Intact PTH: 8 pg/mL, 1,25-dihydroxyvitamin D: elevated, Phosphorus: 3.8 mg/dLEctopic extra-renal 1-alpha-hydroxylase activity
- Serum Calcium: 12.5 mg/dL, Intact PTH: 5 pg/mL, Phosphorus: 2.1 mg/dL, PTHrP: elevatedTumor secretion of a peptide homologous to the amino-terminal end of PTH
- Serum Calcium: 11.5 mg/dL, Intact PTH: 120 pg/mL, Phosphorus: 2.2 mg/dL, 24-hr urine calcium: 350 mg/dayAutonomous overproduction of parathyroid hormone by a single hypercellular gland
- Serum Calcium: 7.5 mg/dL, Intact PTH: 110 pg/mL, Phosphorus: 2.1 mg/dL, Alkaline phosphatase: 250 U/LDefective intestinal calcium absorption leading to secondary parathyroid hyperplasia
Cevap
The accurate diagnostic match depends on differentiating PTH-dependent states (primary hyperparathyroidism, FHH) from PTH-independent states (malignancy, granulomatous disease) and identifying secondary responses to hypocalcemia (vitamin D deficiency).
Each laboratory profile distinctly isolates a core mechanism of calcium homeostasis disruption: a shifted CaSR set-point (FHH), unregulated endogenous hormone production (Primary HPT), ectopic vitamin D activation (Sarcoidosis), ectopic peptide secretion (HHM), or appropriate secondary response to nutrient deficiency (Osteomalacia).
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Anahtar Kavram
Differential diagnosis of calcium and phosphorus metabolic disorders using intact PTH, urine calcium, and specific systemic markers.