Hello and welcome to the Zero to Finals podcast.

My name is Tom and in this episode I'm going to be talking to you about syndrome of inappropriate antidiarrotic hormone.

And you can find written notes on this topic at zero tofinals.com slash s I-A-D-H

or in the endocrinology section of the 0-2-finals medicine book.

So let's get straight into it.

Syndrome of inappropriate antidiarrotic hormone or S-I-A-D-H refers to increased release of antidiuretic

hormone or ADH from the posterior pituitary gland.

This results in increased water reabsorption from the urine which dilutes the blood

and leads to hyponetremia or a low sodium concentration in the blood.

Let's start with the pathophysiology.

Antidioretic hormone, or ADHD, is produced in the hypothalamus and secreted by the posterior

pituitary gland.

It's also known as vasopressin.

Antidiarrotic hormone stimulates water reabsorption from the collecting ducks in the kidneys. There are two potential sources of too much antidiotic hormone. Increased

secretion by the posterior pituitary or or ectopic ADH, most commonly by small cell lung cancer.

Excessive antidiarretic hormone results in increased water reabsorption in the collecting ducts, which dilutes the blood.

This excess water reduces the concentration of sodium,

which is hyponetremia.

The extra water is usually not significant enough to cause fluid overload.

Therefore, S-IADH results in eukolemic hyponotremia.

U refers to normal, vol refers to volume, and emic refers to blood.

So uvalemic refers to a normal volume of blood in the body.

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