Which statement best describes the pseudopseudohypoparathyroidism (PPHP) phenotype?

Which statement best describes the pseudopseudohypoparathyroidism (PPHP) phenotype?

• A. AHO with low calcium and high PTH
• B. AHO with high calcium and high PTH
• C. AHO with normal calcium and normal PTH and no PTH resistance
• D. No AHO phenotype with PTH resistance

Answer: (C)

PPHP is defined by the physical features of Albright hereditary osteodystrophy (AHO) without the biochemical evidence of PTH resistance. In this scenario, the body’s tissues respond to parathyroid hormone normally, so calcium and PTH levels stay within the normal range. The hallmark is having the skeletal/soft-tissue manifestations of AHO (such as characteristic hand bone changes and rounded facial features) without hypocalcemia, hyperphosphatemia, or an elevated PTH level. If PTH resistance were present, you’d expect low calcium with high PTH (and often high phosphate), which is not the case in PPHP. Therefore, the best description is AHO with normal calcium, normal PTH, and no PTH resistance.

PPHP is defined by the physical features of Albright hereditary osteodystrophy (AHO) without the biochemical evidence of PTH resistance. In this scenario, the body’s tissues respond to parathyroid hormone normally, so calcium and PTH levels stay within the normal range. The hallmark is having the skeletal/soft-tissue manifestations of AHO (such as characteristic hand bone changes and rounded facial features) without hypocalcemia, hyperphosphatemia, or an elevated PTH level. If PTH resistance were present, you’d expect low calcium with high PTH (and often high phosphate), which is not the case in PPHP. Therefore, the best description is AHO with normal calcium, normal PTH, and no PTH resistance.