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Pseudohypoparathyroidism

by Carlo Raj, MD
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    00:01 There is a condition known as pesudohypoparathyroidism.

    00:05 I’ll break this entire diagnosis up for you so that you clearly see why we call it false or pseudo and why we call it hypoparathyroidism.

    00:16 So, why is it a false hypoparathyroidism? Because the receptors for PTH aren’t working properly.

    00:23 The particular mutation that you very much want to keep in place is GNAS mutation.

    00:29 This GNAS mutation results in decreased receptor activity for PTH.

    00:37 In other words, this is PTH resistance.

    00:39 So, therefore, the reason we call this pseudohypoparathyroidism is because if there’s PTH resistance, what is the actual PTH levels? Increased.

    00:50 So, we call this pseudohypoparathyroidism, but you still have to call this hypoparathyroidism because if the receptors aren’t working properly in the distal convoluted tubule, then how in the world are you expected to reabsorb your calcium? You’re not.

    01:03 So, therefore, there’s hypocalcemia which is still our topic very much so.

    01:08 So, the serum PTH will be elevated as you can expect because the receptors aren’t working properly and there’s hypocalcemia.

    01:15 In addition, take a look at the hands of your patient here, it’s a child.

    01:19 The child, he or she, is short stature.

    01:23 So, they’re not growing properly.

    01:25 In addition, if you take a look at the fourth and fifth digits, they’re shortened, specifically the fourth and fifth, and you’ll find that there’s something called knuckle-knuckle, dimple-dimple and what that basically means is the following: your metacarpal phalangeal joint, which makes up your knuckle, if you want to go ahead and make a fist, the knuckles here is your metacarpal phalangeal joint.

    01:48 Your fourth and fifth digit will include your ring finger and your pinkie, anatomical position fourth and fifth, one, two, three, four and five.

    01:55 So, these two, the pinkie and the ring finger.

    01:57 The metacarpal phalangeal joints in the fourth and fifth, interesting enough and very specifically for pseudohypoparathyroidism, will be shortened.

    02:05 In addition, that knuckle-knuckle, dimple-dimple literally means you find a knuckle in the first, excuse me, the first, second and third metacarpal phalangeal joints are perfectly okay and then you find dimpling of your fourth and fifth metacarpals.

    02:21 Interesting, isn’t it? You make this diagnosis on your wards you will be then carried down the ward as if you are ha, ha, royalty.

    02:32 The symptoms are not improved by administration of PTH, for obvious reasons.

    02:37 The receptors and the mutation is something that you very much want to commit to memory is called GNAS mutation.


    About the Lecture

    The lecture Pseudohypoparathyroidism by Carlo Raj, MD is from the course Parathyroid Gland Disorders.


    Included Quiz Questions

    1. Defective tyrosine kinase receptor
    2. Autosomal recessive inheritance pattern
    3. PTH resistance
    4. Hypocalcemia
    5. Increased serum PTH
    1. Administration of PTH with no improvement
    2. Administration of GH with no improvement
    3. Administration of calcium with improvement
    4. Administration of PTH with improvement
    5. Administration of calcium without improvement

    Author of lecture Pseudohypoparathyroidism

     Carlo Raj, MD

    Carlo Raj, MD


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