Which of the following lists the three forms of pseudohypoparathyroidism?

• A. PHP Type 1A; PHP Type 1B; PPHP (pseudo pseudo)
• B. PHP Type 1A; PHP Type 2; PPHP (pseudo pseudo)
• C. PHP Type 1B; PPHP (pseudo pseudo); PHP Type 3
• D. PHP Type 1A; PHP Type 1B; PHP Type 2

Answer: (A)

Pseudohypoparathyroidism is defined by resistance to parathyroid hormone at the end organ level, and the forms are distinguished by whether Albright hereditary osteodystrophy (AHO) features are present and which hormones show resistance. The classic trio includes PHP type 1A, which combines AHO with resistance to PTH (and often other hormones like TSH); PHP type 1B, where PTH resistance occurs without AHO features; and PPHP (pseudo-pseudohypoparathyroidism), where AHO features are present but there is no biochemical PTH resistance. This last distinction explains why PPHP is grouped with the other forms as part of pseudohypoparathyroidism variants, whereas PHP type 2 is not included in this trio—it represents a different pattern of PTH resistance without the same AHO association. Therefore, the list of PHP type 1A, PHP type 1B, and PPHP best matches the three recognized forms.