So thank you for the introduction and thank you for the kind invitation Felix and Kai.

We will be diluting your acid Friday a little bit with water and so I'll be switching to

hyponatremia as the next topic.

This will be the outline of my presentation and I think it's important to discuss hyponatremia

for a number of reasons.

One reason being that it's one of the most common or arguably the most common electrolyte

disorder.

It's quite complex and it can be of acute danger to the patient, especially if it develops

acutely.

A strategic point of hyponatremia is that if you come to master it or maybe only half

of it, you are easy to impress your peers or even your supervisors and if you're not

convinced then you can always confuse them with certain things I'll be presenting in

the next few slides.

So that's a strategic point of listening hopefully.

I don't think we should over emphasize hyponatremia because it is not a disease by itself, it's

an indication of an underlying process, so clue to pathophysiology.

If you're doing epidemiological research, hyponatremia and hypernatremia are great because

they always associate with mortality, which is not to say that this is in any way causal.

So since we're moving on to afternoon lectures, I thought it would be good to show you how

many slides to go so that you can coordinate your attention span a little bit during the

presentation.

So the main and bottom line of the presentation will be to focus on water balance because

both hyponatremia, and as the next speaker will illustrate, hypernatremia are water balance

disorders.

So in your thinking I think it's important to focus on water, but obviously this would

be a simplification and therefore I brought this slide from a very nice review article

last year in the New England where you see the determinants of external sodium, potassium

and water balance and also the determinants of the plasma sodium concentration.

I thought it would be especially appropriate to show this because it also shows the novel

insights in non-osmotic sodium storage or as I learned during breakfast, it may now

be osmotic sodium storage, for example, under the skin, which is really pioneered by Jens

Tietze who is from Erlangen.

Another important point in this slide is that potassium is in there and clinicians who have

used the Adroge-Mariaz formula to, for example, correct hyponatremia know to include potassium

as an effect of osmol when you try to predict the changes in sodium concentration.

And the same is true when using urinary sodium plus potassium in the urine to predict changes

in the serum sodium concentration.

It's also I think relevant to mention, this is my most difficult slide, so you can rest

assured after this one, to show you the Edelman formula.

He also was a pioneer in finding out the determinants of the plasma sodium concentration and how

and in this formula you also see in addition to total body water, which is still I think

the primary determinant, exchangeable sodium and potassium.

And there has been a nice experimental study in PICS where they gave the hormone, desmopressin,

in addition to water, induced acute hyponatremia and when you do the analysis only by calculating

the effect of dilution, so only accounting for water, you get this curve and if you then

use the Edelman equation you get a better fit of this curve illustrating that indeed

other factors including exchangeable sodium and potassium are important and determinants

of plasma sodium concentration.

But having said that, think water for the remainder of the presentation.

So if we think water then obviously we need to show a slide on osmoregulation which is