Pseudohypoparathyroidism in MRCP

Pseudo- or pseudopseudohypoparathyroidism in MRCP

Before we understand any disease start off with pseudo-, we must understand the disease without the prefix of pseudo first. Therefore, before talking about pseudohypoparathyroidism, we must understand hypoparathyroidism first.

OK, I think it is easy, hypoparathyroidism just means you do not have enough parathyroid hormone. However, in order for you to understand the clinical and biochemistry features of hypoparathyroidism, you need to know the functions of parathyroid hormone.

Parathyroid hormone is important in calcium metabolism in human. Just remember that your parathyroid hormone will be released if there is hypocalcemia. Various mechanisms will be activated to bring back your calcium level to normal level such as,

1) increasing bone mineral dissolution, thus releasing calcium and phosphorus,

2) increasing calcium absorption but phosporus excretion by kidney,

3) enhancing calcium and phosphorus absorption from the gut,

Therefore, you anticipate patients with hypoparathyroidism to have hypocalcemia and hypophosphatemia.

OK, now you know the basic, pseudohypoparathyroidism just means patients with this disease actually do not have low level of parathyroid hormone ( that's why it is termed pseudo-) but they have the biochemical features of hypoparathyroidism.

How could that be possible? It is possible when your body/tissue does not respond to parathyroid hormone. The most common type of pseudohypoparathyroidism is type 1a, Albright's hereditary osteodystrophy, which is associated with short stature, round facies, obesity and brachydactyly.

As for pseudopseudohypoparathyroidism, it is easy patients have features of pseudohypoparathyroidism but biochemically, they are totally normal!

Just read a bit more how to have the diagnosis of these 2 conditions from your text book although I think it is not so important!