An endocrinology consult team is evaluating laboratory panels for four different patients who have presented with perturbations in calcium and phosphate homeostasis. To establish the correct diagnosis and formulate a management plan, the underlying pathophysiology must be identified. Match each patient's specific biochemical profile with the precise cellular or metabolic mechanism responsible for the findings.
- Elevated serum calcium, decreased serum phosphate, elevated intact PTHAutonomous hypersecretion of peptide from chief cells causing enhanced renal calcium reabsorption and bone resorption
- Decreased serum calcium, elevated serum phosphate, elevated intact PTH, low 1,25-dihydroxyvitamin DLoss of functional renal parenchyma leading to decreased 1-alpha-hydroxylase activity and failure of phosphate excretion
- Elevated serum calcium, high-normal serum phosphate, suppressed intact PTH, elevated 1,25-dihydroxyvitamin DUnregulated, extra-renal macrophage conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D
- Elevated serum calcium, decreased serum phosphate, suppressed intact PTH, elevated PTHrPTumor secretion of a peptide that binds to the PTH-1 receptor, stimulating osteoclastic bone resorption and renal calcium retention
Cevap
Profile 1 maps to autonomous chief cell hypersecretion (primary hyperparathyroidism). Profile 2 maps to loss of renal parenchyma and 1-alpha-hydroxylase activity (CKD). Profile 3 maps to extra-renal macrophage conversion of vitamin D (granulomatous disease). Profile 4 maps to tumor secretion of a PTH analog (humoral hypercalcemia of malignancy).
Each laboratory profile distinctly reflects a specific disruption in the calcium-PTH-vitamin D axis. High calcium with inappropriately high PTH points to primary parathyroid autonomy. Low calcium with high phosphate points to renal failure (secondary hyperparathyroidism). High calcium with suppressed PTH and high active vitamin D points to ectopic 1-alpha-hydroxylase activity (granulomas). High calcium with suppressed PTH and high PTHrP points to a paraneoplastic syndrome.
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Anahtar Kavram
Differential diagnosis of calcium and phosphate homeostasis disorders based on PTH, vitamin D, and PTHrP pathways