What lab pattern would suggest pseudohypoparathyroidism rather than hypoparathyroidism?

• A. Elevated PTH with hypercalcemia and hypophosphatemia
• B. Elevated PTH with hypocalcemia and hyperphosphatemia
• C. Low PTH with hypercalcemia
• D. Normal PTH with normal calcium

Answer: (B)

When the body fails to respond to PTH, you get pseudohypoparathyroidism. The parathyroid glands sense low calcium and pump out more PTH, but the kidneys and bones don’t respond to it. The result is low calcium and high phosphate despite an elevated PTH level. This pattern—high PTH with hypocalcemia and hyperphosphatemia—best distinguishes pseudohypoparathyroidism from true hypoparathyroidism, where PTH would be low and calcium would also be low (with phosphate high). The other patterns don’t reflect the endocrine resistance characteristic of pseudohypoparathyroidism.