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Best post I have read on how to pay donors for kidneys

If you want to start a fight among nephrologists, start talking about paying donors for their kidneys. This may be the most contentious issue in nephrology. I personally am a believer in the concept but trying to imagine a free market for organs makes me nauseous.

Rohin Dhar, at the Priceonomics Blog has put together a brilliant, straight-forward essay describing the problem, showing how current ideas for increasing the organ supply (make donating organs the default after death, paired kidney donation, improved donor-recipient matching) are not working and cannot hope to solve the problem and then goes on to describe a hypothetical organ purchasing system run by medicare. I’m convinced.
When discussing this on twitter, the always interesting Christos Argyropoulos talked a bit about the problem with Greece’s implementation of default organ donation:

@kidney_boy The Iranian system was covered last year in KI if I am not mistaken. Opt out can also backfire as it has in Greece
— ChristosArgyropoulos (@ChristosArgyrop) May 29, 2013

@kidney_boy Opt out legislated in 2011;hugely unpopular, a couple of high profile resignations from the Ntl Transplant body-> # of Txps down
— ChristosArgyropoulos (@ChristosArgyrop) May 29, 2013

@kidney_boy Public pushback makes ICUs reluctant to refer donors,even though almost everyone is. Opt out systems are embraced not imposed
— ChristosArgyropoulos (@ChristosArgyrop) May 29, 2013

An open access review of Iran’s transplant system can be found here (A non-systemic review from McGuil University? I grow feint.) Here is the Kidney International paper Dr. Argyropoulos was referring to.
Look at how the number of transplantations is growing in Iran:
Mitra Mahdavi-Mazdeh. Kidney International, 2012
While it is flat in the US:

USRDS

The current system of paired exchanges and campaigns for kidney donors has noble intentions, but it’s not working. People are needlessly dying as a result.

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And therefore never send to know for whom the bell tolls; It tolls for the TTKG

I was never a big fan of the trans-tubular potassium gradient. I taught it because it was expected core knowledge for medicine residents. While I thought it was a poor test to assist in clinical management I delighted in using it to teach physiology. Understanding how the TTKG works, why it works and the thinking behind the exclusion criteria required sophisticated understanding of potassium and solute handling in the distal nephron.

My primary complaint of the TTKG was how useless it was in the assessment of hyperkalemia. In persistent hyperkalemia the TTKG is always inappropriately low (except in cases of rhabdomyolysis or tumor lysis syndrome where it is possible to get persistent hyperkalemia despite normal renal potassium handling, woe to the patient, whose doctor is relying on the TTKG to diagnose rhabdo). The TTKG was not useful for differentiating the various elements of renal potassium handling that can go off the rails to cause hyperkalemia.

The TTKG could do a neat job of differentiating renal from extra-renal potassium losses in hypokalemia.

Then in 2011 this article came out which showed urea cycling to occur in the late cortical collecting duct. The authors believed that urea delivery to the cortical collecting duct was an important driver of potassium secretion. This broke one of the central assumptions of the TTKG: that no appreciable solute resorption occurs in the medullary collecting duct, the only reason the osmolality increases is the absorption of water.

It looks like the editors of UpToDate have voted the TTKG off the island, here is what UpToDate has to say about the TTKG. In Evaluation of the patient with hypokalemia:

Trans-tubular potassium concentration gradient — The transtubular potassium concentration gradient (TTKG) has been primarily used in the evaluation of patients with hyperkalemia. However, we do not recommend using the TTKG. Details pertaining to the TTKG and the reasons for our recommendation not to use it in hyperkalemia are discussed in detail elsewhere. (See “Causes and evaluation of hyperkalemia in adults”, section on ‘Transtubular potassium gradient’.)

In Causes and evaluation of hyperkalemia in adults

Trans-tubular potassium gradient — It would be desirable to assess the degree of aldosterone activity in patients with hyperkalemia by estimating the tubular fluid potassium concentration at the most distal site of potassium secretion in the cortical collecting tubule. Although this measurement cannot be made in humans, it was proposed that the potassium concentration at this site could be estimated clinically from calculation of the transtubular potassium gradient (TTKG) [91-93]. 

However, in a later publication, the authors of the original studies found that the assumptions underlying the TTKG were not valid [94]. It was concluded that the TTKG was not a reliable test for the diagnosis of hyperkalemia. We recommend not using the TTKG to evaluate patients with hyperkalemia.

RIP TTKG

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Hey Hey it’s your birthday!

Five years.
584 posts.
545,000 pageviews.

Monthly page views. (The posts from 2007 are back dated pages written at a later time that I use for my schedule
and some other projects, first true post was May 30, 2008. Work arounds for dealing with the limits of Blogger)

The first peak is my review of medical calculators for the iPhone.
The second peak is the Margaret Atwood Super Hero Costume experience.
The most recent surge looks less like a peak and hopefully a new plateau, I don’t know the reason but it may have something to do with Google rolling out Penguin 2.0. Decreased search results for spam presumably mean more research results from high quality content.

I asked for a list of nephrology blogs last week and I know have what I believe is a comprehensive list of nephrology blogs oriented to medical professionals. There are dozens (hundreds?) of patient blogs and I did not include those unless they included significant scientific and or nephro-medico-politico content (see Hemo-Doc and Dialysis from the sharp end of the needle). I have found 30 blogs:

Looking at the data you can see how ordinary PBFluids is. The average number of posts is weirdly average, there are a number of blogs with more posts (I fully expect to be passed by the Kidney Doctor in his next bolus of productivity). It is only remarkable in that it is the third oldest active blog, behind the Renal Tsar and RFN.

I also asked you to vote for your favorite post (here and here). We have a winner:

Other honorable mentions:

The blog has been a total gas and I really appreciate all the readers and their feedback. Five years down and I still have plenty of steam. I look forward to celebrating the blog bar mitzvah in 2021.

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App.GoSoapBox.com. Three times a charm.

I have been trying to use GoSoapBox to add some interactivity to my lectures. My first attempt did not work out at all like I wanted it. I used quizzes instead of polls. Then I added  GoSoapBox elements to my non-anion gap lecture and I tried to use it at McClaren Macomb a couple of weeks ago. McClaren built this beautiful auditorium under the hospital. It is state-of-the-art in every way except it has no way to plug in your laptop. My Kingdom for a free VGA cable. So I had to run the lecture off Dropbox on the Window’s machine they had available. Not surprisingly it looked like ass. Then, when I tried to use GoSoapBox, I found that the auditorium had no cell signal penetration (basement) and no wifi (whiskey-tango-foxtrot). Who builds a modern auditorium like that? Total Fail.

On Tuesday I gave the same lecture to the Internal Medicine Residents at Providence. This time the system worked great.

Non-anion gap metabolic acidosis (Powerpoint, PDF)

As the residents were getting food I was joking with a few them and we were stuck on what Batman’s father’s name was. The residents found the Social Q&A section and used it to provide the answer.

I started the lecture with a couple of slides walking them through logging in and getting familiar with the system.
Then I had them do a pre-test to assess what their baseline knowledge of the subject was
Then I posted an ABG and asked them to interpret it.

Use of Winter’s Formula

I had a series of questions on the proper use of the urinary anion gap.

And the lecture finished with a series of quick case vignettes designed to test knowledge of NAGMA.

The feedback on the system I received from the residents was excellent. They loved it. I made a mistake of using my laptop to both run the presentation and manage GoSoapBox. GoSoapBox requires the presenter to open the polls at the appropriate time so students can’t see the poll until the appropriate time. Powerpoint got cranky when I would bounce to my web bowser and then back. Next time I will manage GoSoapBox on my iPad.

Disclaimer: I was given a free 6 month trial of this product. I have received no additional payment or inducement for promotion. I was looking for a system like this and Gary Abud, a friend and Michigan Teacher of the Year, suggested I give this a try. He arranged the free trial.

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The Road to NephMadness

I know I said I would stop talking about NephMadness, but I just got a headset in order to record screen casts and I wanted to try this out. This is my first Screencast, as delivered at Beaumont’s MedEd Week.

If you ever wanted to know what the traffic at PBFluids looks like?
Ever wonder how many copies of the Fluids book are out there?
Ever wonder what the hell the Microbiology Companion is?
All of these secrets and more are revealed in the presentation.
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Please tell me is this a comprehensive list of kidney blogs

I’m trying to generate a master list of renal blogs. I a m looking for blogs that would be of interest to nephrologists, doctors and medical students. I am not looking for patient blogs unless they have significant scientific information. See HemoDoc and Sharp End of the Needle as examples. I am also interested in blogs that are no longer being maintained or may have disappeared from the internet (see Utah Renal Fellows). I am limiting my analysis to English Language, sorry NephroHug.

Here is my list so far:

  1. uremic frost
  2. PBFluids
  3. Renal Fellow Network
  4. Utah Renal Fellows
  5. Nephron Powers
  6. The Kidney Doctor
  7. Sharp end of the needle
  8. eAJKD
  9. uKidney
  10. HemoDoc
  11. Global Kidney Academy
  12. Kidney Notes
  13. ACO Blog
  14. Mahesh’s Top Reads
  15. allen’s Blog
  16. Demystifying Kidney Disease…
  17. WhizzBang
  18. Pediatric Nephrology Blog
  19. Nephrology on Demand
Besides eAJKD any other journals with blogs? ASN deadline is bearing down so a quick response in the comments, by e-mail (joel.topf@gmail.com) or twitter would be appreciated.

Update found another one:
20. Kidney Talk by Shalini Mundra published from Feb 2010 to March 2010.

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May 20, Clinical Trial Day

Clinical trial day is held on May 20th in honor of the first clinical trial, James Lind’s 1747 Trial on the treatment of Scurvy. The ironic thing is how shoddy the study design was. He took 12 sailors with scurvy and divided them into 6 groups of 2. He then treated each group with a different dietary supplement:

  1. quart of cider
  2. sulfuric acid
  3. vinegar
  4. seawater
  5. oranges and lemons
  6. spicy paste and barley water
By the time they ran out of lemons, six days the two sailors in group 5 showed remarkable improvement. No other group showed any improvement. I guess with an N of 2 you better hope for an NNT of 1.
Read the wikipedia page, it has a fascinating account of how this medical breakthrough was ignored and missed for 47 years until lemon juice was issued as part of provisions in 1794.

‘What the Industrial Revolution Did for Us: Modern Medicine’ from James Lind Library on Vimeo.

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Doxepin, mastocytosis and hyponatremia

Patient comes to the ER. She has a a sodium of 119.

Four days earlier the sodium was 134.

ER provides normal saline and the sodium falls to 114.

This is classic SIADH. If you see the serum sodium fall with normal saline, SIADH is your diagnosis.

The fellow ordered all the right tests:

  • Urine Sodium: 81
  • Urine Potassium: 87
  • Urine osmolality: 583
  • Uric acid: 2.6
  • BUN: 13
  • Cr: 0.95
She had negative free water clearance, and a lot of it. For every liter of urine she made it was like she had a 400 mL glass of water.
The patient was on doxepin for mastocytosis. Doxepin is a known cause of SIADH. She also took anti-histamines which cause dry mouth so she was always thirsty. Cruel disease.
From the drug insert
That was stopped and the patient was put on a fluid restriction. She almost immediately turned around and his sodium started to rise. By the following morning the SIADH had completely resolved. Without the inappropriate ADH the pituitary looked at the serum osmolality of 250 and shut down all ADH secretion. This turns the urine to almost pure water. Here are her urine electrolytes from the following morning:
  • Urine Sodium: less than 10 
  • Urine Potassium: 10
  • Urine Osmolality: 111

Her electrolyte free water was 87% of urine output.
If you need refresher, here is a video, different numbers but the concept hold.
Sodium rose to 120 the next morning. The patient was making 250 mL per hour of 87% free water. We were concerned about over correction and decided to start D5W at 100 mL per hour to slow the rate of correction. Her sodium rose at a measured pace after that. We planned on adding DDAVP if the sodium went up to fast. Not needed.

Blogged with patient permission. Release on file at PBFluids world headquarters.