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Joel Topf, MD FACP @kidney_boy
, 18 tweets, 8 min read Read on Twitter
Warning...warning...Tweetorial approaching
Last month Justin Berk @justinberk did a nice tweetorial on non-anion gap metabolic acidosis (NAGMA). If you haven't taken a look at it, go ahead check it out:
Scott @S_brimble asked about the urine osmolar gap and we had a nice little thread:

I think the urine osmolar gap is interesting and I want to expound on it here...but first, a rant on equations in nephrology
One of the weird truths about nephrology is that you spend your fellowship learning all of the equations and then for the first few years after fellowship you learn that they are rubbish.

Don't believe me...
MDRD is unable to correctly estimate the eGFR within 30 ml/min of the truth in 20% of people over 74. kar.kent.ac.uk/53613/2/44Appe…

Dr. Andrew Narva, "most GFR estimating equations have limited accuracy for values above 60 ow.ly/s1tuv"

The trans-tubular potassium gradient #TTKG, dutifully taught for years, was effectively withdrawn by its creator.

pbfluids.com/2013/06/and-th…
FENa? Swapnil @hswapnil pretty much took care of this:

twitter.com/i/moments/9649…
The famous Androgue-Madias Change in Na Formula from the NEJM:

ncbi.nlm.nih.gov/pmc/articles/P…
cjasn.asnjournals.org/content/2/6/10…
cjasn.asnjournals.org/content/2/6/11…

It is so inaccurate that it is dangerous.
The ANION GAP

ncbi.nlm.nih.gov/pubmed/2302951

(OMG I'm taking shots at the anion gap in a tweetorial on non-anion gap metabolic acidosis)
Serum osmolality with hyperglycemia?


More on the change in sodium induced by hyperglycemia:
pbfluids.com/2013/04/pseudo…
Adjusted calcium?

academic.oup.com/ndt/article/23…

The TL;DR is: We made a new formula to estimate ionized Ca in dialysis pts. We tested it and it is more accurate! But being better than the existing formulas did not make it accurate enough to use clinically.
Adjusted calcium conclusion: Don’t calculate the ionized calcium in sick patients. JUST MEASURE IT.
...and yes, even the urine anion gap.
cjasn.asnjournals.org/content/early/…

If you are interested in urine anion gap this is probably the best data ever collected on this, though it is focused on CKD patients, not an area we usually we usually use the urine anion gap.
How crazy that the urine anion gap is 2x higher than the urine NH4+!
They developed an “Improved” Urine Anion Gap, fortified with urine PO4 and sulfate (your local pathologist will likely have a seizure when you demand those labs) is off by 28 points meq/L! Even worse!
The wise doc learns that these equations can’t be used blindly. They can and should be used to teach physiology and to provide a scientific scaffold around fluids and electrolytes. I love the equations but they need to be used sparingly and carefully when treating patients.
With that out of the way, onto the urine anion gap and the urine osmolar gap
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More from @kidney_boy see all

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Everyone knows that potassium is an intracellular ion. And everyone knows that giving 40 mEq of KCl will raise the serum potassium by 0.4 mmol/L.

How much of that KCl infusion remains in the extracellular compartment? Not much, but more than I expected.
Let's start out by calculating the total extracellular potassium in our bodies:

70 kg * 60% water = 42 liters Total body water
one third of total body water is extracellular = 0.33*42 = 14 liters
14 * 3 mEq/L of K in our hypokalemic dude gives extracellular K of 42 mEq
Now lets give this guy 40 mEq of KCl by IV
His potassium goes up to 3.4 mEq/L as we know (clinmedjournals.org/articles/jcnrc…)

new extracellular K is 3.4 * 14 or 47.6 mEq of potassium
Read 5 tweets
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I spoke about the urine anion gap with the @curbsiders but I want to emphasize what is oing on here:

In metabolic acidosis the kidneys try to excrete excess acid as ammonium NH4+. This is essential because even at a pH of 4.4, the hydrogen concentration is
The right answer is 0.04 mmol/L. To get rid of even a modest daily acid load of 50 mmol would require:

50 mmol of H+/ 0.04 mmol/L = 1,250 liters of urine
So the protons must be smuggled out and there are two choices: phosphate and ammonium. The trouble with phosphate is it cannot be ramped up. The amount of phosphate available to secrete is limited by dietary phosphorus intake.
Read 18 tweets
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I’m going to throw my hat in the Tweetorial ring.

Sometimes salt tablets work for hyponatremia and sometimes they don’t. How can you figure out when to use them and when not to?
The kidney regulates total body sodium and total body water independently. The renin angiotensin aldosterone system regulates total body sodium while ADH (water excretion) and thirst (water intake) regulates total body water.

Hyponatremia is a failure of the regulation of:
Though the two systems are independent there is some cross-over. When people get profound drops in perfusion ADH will be up regulated. This usually requires at least a 10-15% drop in perfusion.
Read 36 tweets

Related threads

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This study is yet another one in a growing list demonstrating that dysplastic nevi are NOT obligate precursor lesions for melanoma. Let me give you a brief history/discussion of the 40 year old controversy.

A thread/#Tweetorial 👇🏾👇🏾👇🏾
Dysplastic nevi are atypical looking moles that appear on the skin that can look like melanoma.
The term clinically atypical nevus (CAN) describes the clinical appearance of a mole on visual examination, while dysplastic nevus (DN) refers to the histopathological features of the lesion.
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Hold my bubbly water...
This is going to be fun
Dear @KenPaxtonTX federal law prohibits you from buying a gun because you’re under a felony criminal indictment
18 U.S. Code § 922 - Unlawful acts
One of many...
Come on Ken...tell the good people of Texas and “Mercia how many times you’ve delayed your criminal fraud trial?
Is it 2?
Is it 3?
Is it 4?
Nope FIVE times and the tax payers of Texas are footing your legal bills.
Gawd
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"Well, well, well." Grace recalls her Porygon and stows it on her belt. "Looks like you're out of Pokemon. You owe me something~" Her boot lands on your groin. She smiles and teases until you fall under her spell.

Next time you're in her gym, it's cleaner than last time. Weird.
(Picture by @WhatdoIDH !)
Her lips glow pink. She plants a mind-fogging Sweet Kiss on your cheek. The spell swirls into your mind and clouds your thoughts.

"What's wrong, dear? Confused?" She strokes your cheek and whispers into your ear. "Maybe you're worn out from wasting my pokemon's time."
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Introduction to Archival Research: A Thread
This could also rightly be called Archives 101 & Why Theory Matters. This is the way I explain it, other archivists will disagree. Feel free to ask questions or comment how you would explain it differently/how you contextualise it differently.
We're going to start at the beginning. What is an archive? An archive is the documents and records created by a person or institution during the course of their life and/or work. Also the location (physical or digital) where all of these ‘archives’ are stored.
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Last night I posted this lovely gross picture; I’m now adding a couple of histologic images. Kudos to @kriyer68 and @DrAldehyde for being the first to submit the correct answer- this is indeed a synovial sarcoma! Not a bad time for a #Tweetorial #BSTPath
Synovial sarcoma is actually uncommon in joint cavities & does not recapitulate synovium in any way. Its rare amongst soft tissue sarcomas, representing only 5-10% of the cases. The disease is most prevalent in teenagers & young adults; 50% of cases are seen in pediatric patients
These most commonly present as pain in the affected site with an associated mass. In many cases the duration of symptoms is 2-5 years. They are seen most commonly in the extremities and are often associated with tendons. #BSTPath
Read 12 tweets
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1/
 on January 17th, 2018
@caitoz made a terrible error
@caitoz decided to debate @ThomasWictor on Syria

Two HeavyWeights
Two Equals
Two Opposites

This Tweetstorm is the play-by-play
then you can decide how it went

I have to go slow
I'm doing screen captures
But this was epic
1/
 Appears the debate started around 3pm on Jan 17th

@Caitoz was discussing Tillerson comments about Syria

tweet 👇
2/
 @Caitoz then discussed it further
by quoting an article
and
stating

"#MAGA"

(my browser that copies tweets has a problem with attachments, but the tweets will be linked below for your verification)

tweet #2 👇
Read 109 tweets

Trending hashtags

#modern #AmJGastro #tweetorial #BVS #pembified #OCTImaging #TipsForNewDocs #Supremacist #RussianActiveMeasures #Hungary #Tweetorial #Collagen #TTE #MAGA #surgery #OCTimaging #doublethink #pathtweet #Israel #AI #pathology #ihcpath #Afib #verification #PFEs

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