In PPHP, what are the typical serum calcium and PTH levels?

• A. Low calcium and high PTH
• B. Low calcium and low PTH
• C. High calcium and high PTH
• D. Normal calcium and normal PTH

Answer: (D)

Pseudopseudohypoparathyroidism (PPHP) presents with the physical features of Albright hereditary osteodystrophy, but without true PTH resistance. The underlying genetic imprinting can cause the characteristic phenotype without disrupting the PTH signaling pathway in the kidneys and bones. Because PTH resistance is not present, calcium and phosphate balance remains normal, so serum calcium is in the normal range and PTH levels stay normal as well. In contrast, true PTH resistance (pseudohypoparathyroidism) would show low calcium, high phosphate, and elevated PTH. Thus, the typical pattern in PPHP is normal calcium and normal PTH.