Question

All of the following statements about pseudohypoparathyroidism are true, except:

• A. Decreased serum PTH
• B. Decreased serum calcium
• C. Increased serum phosphate
• D. Albright hereditary osteodystrophy

Hint:

In pseudohypoparathyroidism PTH is high because tissues resist it.

Answer 1

The Correct Option is A

The trick word here is pseudo. The hormone is present and even abundant, but the tissues ignore it because the receptor signalling pathway is broken. Keep that resistance idea front and centre.

Since the kidney and bone cannot hear the PTH message, calcium cannot be raised and phosphate cannot be excreted. The result is low blood calcium and high blood phosphate, exactly mimicking a hormone deficiency. So both the decreased calcium and the increased phosphate statements are genuine features.

Now the discriminator. With calcium chronically low, the parathyroid glands keep firing and the measured PTH level rises rather than falls. So the line claiming decreased serum PTH is false, and that is the answer. This high PTH with low calcium is what separates pseudohypoparathyroidism from real hypoparathyroidism, where PTH is low.

Finally, the type 1a form carries Albright hereditary osteodystrophy, with its round face, short stature, and shortened fourth and fifth metacarpals, so that statement is correct.
\[\boxed{\text{Decreased serum PTH}}\]