Friday, February 24, 2023

The Mountain Model of Hyponatremia

“The Mountain Model of Hyponatremia” is an educational project by Joel Topf and me.

Imagine this is the clinical scenario of severe hyponatremia:

  • You are driving in a car at the top of a mountain. (The top of the mountain is the low sodium level.) 
  • There is a forest fire behind you. (The fire represents brain swelling and seizures if the sodium level drops much lower.)
  • Your goal is to drive safely to the bottom of the mountain. (The bottom of the mountain is a normal sodium level.)
  • But, to be safe, you must follow the “sodium speed limit”: a rise in sodium of 8 every 24 hours. (If you exceed this “sodium speed limit,” you increase the risk of a car crash: osmotic demyelination syndrome.)

Based on this model, there are five possible therapies for patients with hyponatremia: 

  1. Press the accelerator (when the car is in “drive”): 3% (hypertonic) saline
  2. Press the accelerator (but the car may be in “drive,” “neutral,” or even “reverse”): 0.9% (normal) saline
  3. Cruise control: desmopressin/DDAVP and 3% (hypertonic) saline (“proactive strategy”)
  4. Press the brake: desmopressin/DDAVP (or large amounts of D5W) (“reactive strategy”)
  5. Reverse gear: desmopressin/DDAVP and D5W (“rescue strategy”)
Additional technical notes:
  1. The “sodium speed limit” might change depending on the clinical situation.
  2. The slope of the mountain represents rapid correction due to water diuresis that can occur in patients with a reversible cause of hyponatremia (hypovolemia, beer potomania/low solute hyponatremia, adrenal insufficiency, and other causes).
  3. If a patient has SIADH, the mountain might slope upward. (This is a separate figure.)
  4. If the patient has SIADH, giving 0.9% (normal) saline may not work or may cause the sodium to go down — when you press the accelerator, the car may be in “neutral” or even “reverse.” (See therapy #2.) 
  5. Usually, fluid restriction is also important. 
  6. In the right clinical circumstances, other therapies might include salt tablets, loop diuretics, urea, and vaptans. (These are not included in the model.) 

Saturday, February 4, 2023

Calculators for EKFC eGFRcys, EKFC eGFRcr, and EKFC eGFRcr-cys

The most accurate race-free eGFR equation (EKFC eGFRcys) isn't yet available in EMRs or in a calculator app, so here's an Apple shortcut to use on the iPhone or Mac. Also, here’s a calculator as a Google spreadsheet of the EKFC eGFRcys, EKFC eGFRcr, and EKFC eGFRcr-cys equations

Comments/corrections are welcome. Please message @joshuaschwimmer on Twitter.

Thanks to Dr. Hans Pottel for his guidance.


(Yes, this is important enough to post to KidneyNotes after a break of over 5 years. Hello!)

Wednesday, December 2, 2015

“We’ve selected our case of the week. This surgical...

"We've selected our case of the week. This surgical procedure was relatively common prior to the widespread use of antibiotics. Do you know what it is?" By figure1 on Instagram

Posted on infosnack.

“Baking Soda and Vinegar” via

"Baking Soda and Vinegar" via

Posted on infosnack.

Friday, November 20, 2015

Thursday, November 5, 2015

“The $3.7 billion World Trade Center Transportation Hub...

"The $3.7 billion World Trade Center Transportation Hub will soon house the luxury Westfield World Trade Center mall, which calls itself "the most complete retail destination in New York City, the most alluring retail landmark in the world." But a persistent water leak, among other things, has delayed the opening of the $1.4 billion shopping center. The problems of building such a complex structure — a four-block-long interconnected network with the soaring Oculus as its centerpiece — have nearly doubled the price tag that was estimated 12 years ago. @bryanthomasphoto photographed construction crews working at the #Oculus on Monday." By nytimes on Instagram.

Posted on infosnack.

Wednesday, October 7, 2015

Monday, September 14, 2015

“This drawing of one of our specimens is by Cynthia Muñoz,...

"This drawing of one of our specimens is by Cynthia Muñoz, who participated in our Anatomical Anomalies class earlier this year. We're super excited to announce that we're running another class this season! Check out for details and to sign up. Link also in profile.

Drawing: graphite on paper. Skeleton of Cephalothoracopagus Twins. Fused at the head and chest. To see more photos from this series visit:

#medical #pathology #art #sketching #drawing #philadelphia #medicaldrawing #skeleton #twins" By muttermuseum on Instagram.

Posted on infosnack.

Friday, September 11, 2015

High Blood Pressure Treatment Should Be More Aggressive, Study Finds— Joshua...

Posted on infosnack.

Monday, August 31, 2015

f.lux, my favorite Mac app for automatically dimming the screen at night, just got a major update....

Posted on infosnack.

Thursday, August 27, 2015

Article on Doctor Ratings in the Wall Street Journal— Joshua Schwimmer, MD...

Posted on infosnack.

Wednesday, August 19, 2015

Wednesday, August 12, 2015

My photos from the epic all-night insane puzzle game Midnight Madness 2015 which raised $3.1 million...

Posted on infosnack.

Tuesday, August 11, 2015

Midnight Madness: Inside Wall Street’s massive all-night puzzle challenge...

Posted on infosnack.