Which statement about PHP Type 1A and PHP Type 1B labs is true?

Which statement about PHP Type 1A and PHP Type 1B labs is true?

• A. Type 1A shows normal labs; Type 1B shows normal labs
• B. Type 1A and Type 1B both show high calcium
• C. Both have hypocalcemia, hyperphosphatemia, and elevated PTH
• D. Type 1B shows low PTH despite high phosphate

Answer: (C)

Both Type 1A and Type 1B are forms of pseudohypoparathyroidism, meaning the body makes PTH but tissues don’t respond to it. In this situation, the kidney and bone don’t react to PTH, so calcium can’t be properly mobilized or reabsorbed, and phosphate isn’t adequately excreted. The result is low calcium and high phosphate in the blood, which stimulates the parathyroid glands to release even more PTH, hence elevated PTH levels. So, the typical lab pattern for both types is hypocalcemia, hyperphosphatemia, and elevated PTH. The other statements clash with this pattern: normal labs wouldn’t reflect PTH resistance, high calcium wouldn’t fit, and low PTH with high phosphate would imply hypoparathyroidism rather than pseudohypoparathyroidism.

Both Type 1A and Type 1B are forms of pseudohypoparathyroidism, meaning the body makes PTH but tissues don’t respond to it. In this situation, the kidney and bone don’t react to PTH, so calcium can’t be properly mobilized or reabsorbed, and phosphate isn’t adequately excreted. The result is low calcium and high phosphate in the blood, which stimulates the parathyroid glands to release even more PTH, hence elevated PTH levels. So, the typical lab pattern for both types is hypocalcemia, hyperphosphatemia, and elevated PTH. The other statements clash with this pattern: normal labs wouldn’t reflect PTH resistance, high calcium wouldn’t fit, and low PTH with high phosphate would imply hypoparathyroidism rather than pseudohypoparathyroidism.