musings of a salt whisperer
Last week I posted a tweetorial on pseudohyperkalemia due to CLL and a high white blood cell count.
This case peaked with a potassium of 9.5. Pretty frightening, but that was nothing compared to the potassium of 15.5 I saw in 2014. Details here.
I had another case of pseudohyperkalemia in 2011. That one was due to thrombocytosis.
In response to my Tweetorial, Yash Chivate shared a case of pseudohyperkalemia of his own.
Awesome, current resource on onconephrology from the ASN. Nineteen chapters with everything you need to be a superior consultant nephrologist
The more you learn the cheaper that ASN membership looks.
I received this DM today (my DMs are open. I was nervous about opening DMs but a year later I would rate the experiment as a delightful success. It has opened up Twitter to many new discussions that otherwise would not have occurred).
Hi Dr. Topf, I’m a final year medical student from the UK. I’ve been following you for a while due to my interest in renal medicine. Are there any books/online resources that you would recommend to learn renal physiology? I feel that I lack fundamental principles and concepts which I’d like to improve. Thanks!
Arnav
This is actually a relatively common question and I am going to attempt to write this post so I can link to it in the future.
The answer depends on the goals of the student
Slim, readable. Good choice.
This is designed to be part of a workshop but it can be read on its own.
This list is for the learner who is looking to know what to do.
Of course I’m one of the authors and I edited every single word in this book but a year later I still am amazed at how well this review book walks the tightrope of being concise without over simplifying complex topics. I may be biased, but I think this is an excellent book.
Before Secrets this was my go to recommendation, but this book is getting long. I’m beginning to think this may be too long for a student resident on a one month nephrology rotation. That said you can’t find better renal educators that editors than Gilbert and Weiner.
Fluid, Electrolyte and Acid Base Companion
It is strange that one of the things I am most proud of in my entire career is a book I wrote as a resident but it is no exaggeration to say this book for transformative for my life. I poured five years of work into this project and i think it stands up. However you should skip the tremendously outdated and overly complex section on the treatment hyponatremia and instead read the European Clinical Practice Guidelines.
Burton Rose’s Clinical Physiology of Acid Base and Electrolyte Disorders.
People look at the copyright on Rose’s electrolyte book and conclude the book is out of date.
It is.
It doesn’t matter.
Rose excels at providing the reader a cohesive mental model of how the kidneys work so that things make sense. Then if you need to learn more and get a more up to date and nuanced view of how the kidney works it is pretty simple to plug those updates into your mental model of the kidney.
Use the following:
Read the first three cover-to-cover and then cover-to-cover again. The KDIGO Guidelines will give you the state-of-the-art for many of the important issues in Nephrology and the full guidelines provide a solid scientific rational for why the guideline are the way they are. You should have more than a superficial familiarity with the guidelines. Use UpToDate and Nature Reviews to go deep on every weird, rare, or interesting patient. Use the last one to stay up to date with clinical research. That’ll do. That’ll do quite nicely.
What did I miss? What are your favorites. Hit me up on #MedTwitter or slide into my DMs.
Some good updates from Twitter
And Mir Tariq Ali reminded me of major omission to my list. I forgot Daugirdas’ Handbook of Dialysis. This is the third book that every nephrology fellow should read cover to cover and then read again.
My team was consulted for acute kidney injury (AKI) and hyperkalemia. Before we saw the patient they had already been given the standard, calcium, bicarb, and insulin/glucose cocktail. This had no effect. Potassium went from 6.4 to 6.4.
The patient was still making urine. The AKI was due to emergency surgery with an impressive estimated blood loss (translation: blood loss measured in liters). We gave a liter of NS, 80mg of IV furosemide and 0.2 mg of oral fludrocortisone. Potassium went from 6.4 to 3.4 despite a further increase in the serum creatinine.
Remember to use the kidney for treating hyperkalemia. Even in AKI you can get impressive results.
Renal clearance of potassium is entirely dependent on the cortical collecting duct, specifically the principal cells. It is a multi-step process:
That is how potassium is excreted but, how is potassium regulated? There are two primary components to regulation:
The medical management we provided takes care of both aspects of potassium regulation, the furosemide and saline makes sure there is a robust supply of sodium delivered distally and the fludrocortisone makes sure there is ample aldosterone activity to assist with potassium clearance.