Thread by @TheRealDoctorT

(See pinned tweet for privacy statement. Hyponatremia is a maddeningly simple yet complex subject and my thread below is by NO means comprehensive.)

Sally is 85. She enjoys doing the crossword puzzle in the paper, playing bridge, and spending time with her dog, Alphonso. 1/

Her grandkids call him The Fonz. Sally doesn’t get it but finds it hilarious when they say, “Heyyyyyy!” as they pet him.

Sally hasn’t been feeling well for about a week.

She thinks she might have eaten something bad. Her stomach is roiling, and she’s been having nausea. 2/

She’s deathly afraid of getting dehydrated after a bad bout with a kidney stone several years ago, and so she makes sure she is drinking a ton of water.

In fact, she has been gulping water almost constantly for the last 48 hours... 3/

Sally takes medications for blood pressure and cholesterol. One of her blood pressure medications is a diuretic, called a thiazide. It is one of the most commonly prescribed blood pressure medications in the world, and works well.

Something strange is starting to happen. 4/

Sally’s nausea and pain are resolving, but she’s feeling worse and worse. It’s something she can’t quite put into words.

She feels like she’s floating inside her own body. 5/

Much later when asked to describe what it felt like, she will say it felt like her arms and legs were trying to detach themselves and crawl away from her torso.

Not painful, just ... disconnected.

Eventually she starts to become increasingly confused. 6/

She can’t work the crossword anymore. She’s having trouble thinking.

Alphonso senses something wrong, and starts barking.

As she finally slumps over, minimally responsive, it is her dog’s continual barking that saves her life.

Neighbors come to check on her, and dial 911. 7/

In the ER, a stroke workup is initiated. Bloodwork is sent and CT scans are done. Sally is more awake, but remains confused. A lab value comes back critically low.

Sodium.

Low sodium is one of the most commonly occurring electrolyte abnormalities in the human body. 8/

If salt (sodium chloride) concentrations in the blood get too low, it can result in swelling of the brain, leading to confusion, weakness, seizures, and even death.

To understand low sodium (or “hyponatremia”), you have to understand how the human body handles water... 9/

Hyponatremia is, at its heart, actually a water problem, not a sodium problem.

Excess water relative to salt leads to a drop in salt concentration, sort of like dilution.

The problem here isn’t a lack of salt.

It’s too much water. 10/

Normally the kidneys’ regulatory mechanisms can quickly get rid of excess water.

You can pee a staggering amount of water in 24 hours.

Sometimes, however, the systems are interfered with by meds or illness, and the kidneys start holding on to water instead of excreting it. 11/

When Sally got sick, a combination of factors contributed to her kidneys’ water retention. This, together with her heavy water intake, led to a steady drop in her serum sodium concentration.

The normal serum sodium level is around about 140.

Sally’s is 109. 12/

Anything less than 130 typically starts to get symptomatic, and less than 120 is dangerously so.

At a level of 109, Sally is in critical danger.

The ER doctor orders 3% saline, or “hypertonic” saline. Nicknamed “hot salt,” this is extremely concentrated saltwater. 13/

As the 3% saline is started, a phone call is also made to consult me. Here in South Texas, management of hyponatremia is one of my most common consult requests.

Sally is already feeling better.

As she receives the 3% intravenously she feels like she is coming out of a fog. 14/

She is able to start thinking again, slowly. She feels less disconnected as the hypertonic saline helps reduce the swelling in her brain from water shifts.

By the time I see her, Sally is able to smile and greet me.

She says she feels so much better.

But I’m worried. 15/

In fact, as I look at the latest labs, my heart is sinking.

Sally is now in even graver danger than when she came in.

Sodium abnormalities can often be unpredictable. As dangerous as low sodium is, correcting the sodium level too fast can be just as bad if not worse. 16/

There is a greatly feared complication of sodium overcorrection called “osmotic demyelination syndrome.”

A form of brain damage, it means the patient can end up “locked in” to their body, paralyzed, unable to do anything but blink their eyes.

It is potentially irreversible. 17/

The 3% saline by the ER doctor was the right call. It was a limited amount and was stopped long ago.

Everything has been managed correctly, by the book so far, but as I review the trajectory of Sally’s sodium, I realize that an overshoot is becoming inevitable. 18/

Her kidneys are starting to fix the problem, and they’re fixing it too fast.

I give her a med called DDAVP to make her hold on to water and lower her urine output. Also I give her IV water to try and “re-dilute” her sodium level and put the brakes on this overcorrection. 19/

This is challenging to do, and requires hourly sodium checks until we are out of the woods. This means my night, and sleep, will be shot, but so be it.

Every hour, I receive a phone call updating me on the sodium level. I titrate the IV water infusion rates as needed. 20/

I sleep in between the calls.

The next morning when I come in to see her, Sally is working a crossword puzzle.

She smiles and greets me, not remembering me from the ER. She’s doing so much better, and is going to recover well. I’m so happy, and also deeply relieved. 21/

She’s worried about Alphonso, but her family is taking care of the Fonz.

I picture a little dog in a leather jacket.

He looks ... salty.

I can’t help but laugh.

I have a full day ahead. Miles to go before I sleep.

We finish talking. I write a note in her chart, and move on.