Tony Breu Profile picture
Hospitalist, VA Boston. Faculty, @HMSbioethics. Co-host, @CuriousClinPod. Usually at #AMreport. Views are my own.
Rockyang MD Profile picture Bollam rajesh Profile picture Inmate 6238 Profile picture Reza Hosseini, MD MPH Profile picture Karen Reynolds MD, MHQS Profile picture 95 subscribed
Feb 22 10 tweets 6 min read
1/10
🤔Why is pulmonary embolism (PE) relatively rare in those with Factor V Leiden?

This Factor V Leiden Paradox was pointed out to me by @DrSamelsonJones after I posted about a similar difference with Behçet Syndrome.

Let's have a look. 2/
In 1993, Dahlback, Carlsson, and Svensson first described a heritable resistance to activated protein C.

A year later the same group found this to be the most common form of hereditary hypercoagulability.


ncbi.nlm.nih.gov/pmc/articles/P…
pubmed.ncbi.nlm.nih.gov/8302317/Image
Image
Feb 18 9 tweets 4 min read
1/8
🤔Why is pulmonary embolism (PE) so rare in Behçet Syndrome?

The condition is associated with a 14-fold increased risk of deep vein thrombosis (DVT) but almost none of these result in PE.

What is it about the thrombus in Behçet that makes it so unable to embolize? 2/
Numerous case series have reported a markedly increased risk of deep vein thrombosis with Behçet Syndrome.

One reported the following rates of venous thrombosis:
➣ Behçet Syndrome: 18/73 (25%)
➣ Controls: 4/146 (3%)

pubmed.ncbi.nlm.nih.gov/11426022/Image
Dec 12, 2023 7 tweets 3 min read
1/7
🤔What is the hemodynamic response to a chronic hemoglobin of 1.5 g/dL.

A fascinating 1963 study published in @CircAHA provides some interesting answers. Let's have a look at Patient One.

ahajournals.org/doi/pdf/10.116…
Image @CircAHA 2/
Patient One had chronic anemia with a hemoglobin 1.5 g/dL. You'll see that before receiving blood they had the following cardiac parameter:

• HR 100 (elevated)
• Cardiac index 8.9 (elevated)
• Stroke index 89 (elevated) Image
Dec 10, 2023 17 tweets 7 min read
1/17
🤔Why don't we transfuse to a normal hemoglobin?

In many cases, we aim to restore values to the normal range. Potassium and other electrolytes. Even white blood cells.

But not hemoglobin.

In most situations, we accept >7g/dL, far less than normal. Why are we so tolerant? Image 2/
The principal rationale for red blood cell transfusion is to increase the O₂-carrying capacity and therefore O₂ delivery to tissues.

As hemoglobin is lowered O₂ delivery decreases, assuming all else remains unchanged.

So giving blood makes sense.
Oct 12, 2023 8 tweets 3 min read
1/7 - The Mystery

A 57-year-old presents with the following labs:

WBC 2.7 / HGB 2.2 / PLT 111
Bili 3.2 (direct 0.4)
LDH 4360
Haptoglobin <10
INR 1.6 / PTT 35
Reticulocyte count 3.4
Smear with schistocytes

🤔What is the most likely diagnosis? 2/7 - The Answer

💡This patient was diagnosed with profound B12 deficiency secondary to pernicious anemia (PA)!
Aug 29, 2023 17 tweets 7 min read
1/14
In a recent thread I discussed immunosuppression after xenograft heart valve replacement.

Did you know that we also use homografts (i.e., valves taken from human cadavers)? I didn't.

And these valves don't require HLA and ABO matching or immunosuppression either.

Why? 2/
Valve replacement surgery emerged in the 1950s to mitigate the dreadful outcomes of progressive heart valve failure.

The first valve was plastic and was placed in the descending aorta of a 30-year-old woman with rheumatic heart disease.

pubmed.ncbi.nlm.nih.gov/24539965/
Aug 28, 2023 18 tweets 8 min read
1/18
🤔Why don't we use immunosuppression after bioprosthetic valve replacement?

Not only is the graft not self, but most aren't even from the same species and instead are from cows or pigs.

But unlike other transplants, we forego immunosuppression. Why?

Let's have a look. Image 2/
First, some history.

The first valve replacements were performed in the 1950s and were made of plastic or metal.

The desire to forego anticoagulation saw the emergence of homografts (i.e., valves taken from human cadavers) in the 1960s.

dx.doi.org/10.4414/cvm.20…
Image
Jul 15, 2023 13 tweets 6 min read
1/13
🤔Why does iron administration relieve symptoms of restless leg syndrome (RLS) in some patients?

Turns out BRAIN iron deficiency matters more.

Let's have a look. 2/
In 1945 Karl-Axel Ekbom offered the first description of RLS.

Soon after Nils Nordlander observed that blood transfusion treated the condition. He then administered IV iron to 21 patients.

💡20 (95%) saw the complete resolution of symptoms!

https://t.co/X22mRa1srfpubmed.ncbi.nlm.nih.gov/13079659/
Image
Jul 7, 2023 8 tweets 3 min read
1/6
🤔Why does alcohol burn?

Placed on a wound or downed in a shot, alcohol leads to a noxious sensation on my skin or in my esophagus.

Sometimes it feels good, other times, not so much.

Let's have a look. 2/
The noxious burning sensation results from the activation of the capsaicin receptor.

Identified in 1997 and named vanilloid receptor subtype 1 (VR1), it is activated by:
🌶️ Capsaicin in hot and spicy foods
🌡️ Temperatures above 40-42ºC (104-107.6ºF)

pubmed.ncbi.nlm.nih.gov/9349813/
Image
Jul 2, 2023 15 tweets 6 min read
1/15
🤔Why does drinking alcohol make me feel warm?

I was recently at a soccer game with colder weather than anticipated. I told my friend I wish I had a flask with whisky to "warm me up." I soon realized, I didn't know how it had this effect.

Let's have a look. 2/
For centuries we've known that alcohol leads to a sensation of warmth.

In 1915 BMJ published letters on the military Rum Ration. Much of the debate related to this effect with Woodman arguing that coffee is hardly a practical substitute for alcohol.

bmj.com/content/1/2827…
Image
May 3, 2023 9 tweets 4 min read
I argue against sodium restriction in acute heart failure. The line of reasoning is that:

(1) Current evidence suggests restriction is not helpful.
(2) And may be harmful.
(3) There is a solid pathophysiologic basis for this evidence Regarding evidence, the trials are small but generally consistent.

In 2013 Aliti showed no differences in change in weight or clinical congestion when a 800 mg/d sodium diet was compared with no restriction.

More thirst was seen in the restriction arm.

pubmed.ncbi.nlm.nih.gov/23689381/ ImageImage
Apr 30, 2023 18 tweets 15 min read
1/18
🤔Why is the BUN/Cr elevated in upper gastrointestinal bleeding?

This question has been covered by @AdamRodmanMD and @WilliamAird4 but the literature is SO FASCINATING that I had to review it myself. @AdamRodmanMD @WilliamAird4 2/
In 1933 LV Sanguinetti reported the association between GI bleeding and elevated BUN.

The next two decades were the golden age of experimentation on this question with dozens of studies performed with the goal of identifying the cause.

dx.doi.org/10.1001/archsu… Image
Apr 29, 2023 12 tweets 5 min read
1/12
🤔Why is plasma albumin low in nephrotic syndrome?

"Urinary losses!" seems like the obvious answer.

But there is much more to it.

Let's have a look. 2/
Recall that excretion of >3.5 g/day of protein is required for a diagnosis of nephrotic syndrome (NS).

In one study of 982 patients, the median value for proteinuria in NS was 6.7 g/day.

Can the liver make up for this daily loss?

pubmed.ncbi.nlm.nih.gov/28425160/ Image
Apr 24, 2023 15 tweets 8 min read
1/15
🤔Why does ticagrelor cause dyspnea?

In one analysis, dyspnea was the number one reason for drug discontinuation, accounting for 56% of withdrawals!

Let's have a look at this unexpected side effect of an anti-platelet agent.

pubmed.ncbi.nlm.nih.gov/24612612/
Image 2/
The association between ticagrelor and dyspnea has been observed since the initial phase 2 trials.

Recent meta-analyses show significantly higher rates when compared with the more common P2Y₁₂ inhibitor, clopidogrel.

☞ OR = 1.9

ncbi.nlm.nih.gov/pmc/articles/P…
Image
Mar 15, 2023 8 tweets 4 min read
1/8 - The Mystery

It's 1981, 10 years before filgrastim is approved by the FDA.

You're hoping to mitigate chemotherapy-induced neutropenia in one of your patients.

🤔What medication might provide this ELEMENT of cancer care? 2/8 - The Answer

LITHIUM!

💡Soon after its use for bipolar emerged, LEUKOCYTOSIS was observed to be a common side effect.

pubmed.ncbi.nlm.nih.gov/20034171/
Mar 12, 2023 13 tweets 6 min read
1/13
🤔Why does smoking cause leukocytosis?

I see this with some frequency but haven't taken to time to understand the mechanism.

Let's have a look. 2/
The association between smoking and increased white blood cell (WBC) count was first noted in 1970. The following counts were observed:

➣Never smoker: 5.8 × 10⁹/L
➣Quit: 6.0
➣Current (<20 cigarettes/day): 7.1
➣Current (≥20 cigarettes/day): 7.6

pubmed.ncbi.nlm.nih.gov/4194535/
Jan 21, 2023 16 tweets 7 min read
1/16
🤔Why does carcinoid syndrome affect the right heart valves more often than the left heart valves?

The difference is striking.

Let's have a look. 2/
Let's start by confirming that the valves of the right heart are disproportionately affected.

A 1993 study of 74 patients with carcinoid heart disease reported the following rates by valve:

➤97% tricuspid
➤88% pulmonic
➤7% mitral
➤3% aortic

pubmed.ncbi.nlm.nih.gov/7681733/
Jan 12, 2023 6 tweets 3 min read
1/6 - The Mystery

🤔Why do we use thrombopoietin (TPO) receptor agonists in immune thrombocytopenia (ITP)?

If the issue is peripheral destruction of platelets, why would ramping up TPO help?

Turns out, ITP Is more than a disease of platelet destruction! 2/6 - The Solution

In ITP, platelet destruction is central. But...

💡Depressed platelet production plays a role as well!

pubmed.ncbi.nlm.nih.gov/31483965/
Jan 8, 2023 18 tweets 8 min read
1/18
🤔Why does the diagnosis of Streptococcus bovis bacteremia immediately raise the specter of colon cancer?

If colon cancer leads to barrier disruption and translocation of bacteria into the blood, shouldn't E. coli bacteremia raise the same concern?

Is S. bovis unique? 2/
In 1977, Klein et al reported a strong association between colon cancer and fecal carriage of S. bovis.

☞ 10% of controls were fecal carriers of S. bovis

versus

☞ 56% of those with colon cancer

pubmed.ncbi.nlm.nih.gov/408687/
Dec 31, 2022 4 tweets 2 min read
Are humans prokaryotes or eukaryotes?

Clearly, the answer is that we're eukaryotic. But notice that nearly 90% of our cells lack a nucleus.

☞ 84% are red blood cells
☞ 5% are platelets

ncbi.nlm.nih.gov/pmc/articles/P… Red blood cells (RBCs) begin with a nucleus and organelles.

During erythropoiesis they under enucleation and organelle clearance.

That leaves mature RBCs without a nucleus, mitochondria, ribosomes, or other organelles.

Sounds prokaryotic.

ncbi.nlm.nih.gov/pmc/articles/P…
Dec 31, 2022 9 tweets 4 min read
1/9
Is a human body more human or more bacteria?

It depends on how you answer the question. 2/
Let's start with human cells.

A 2016 study estimated that a 70 kg nonanemic male to have approximately:

🧍🏿‍♂️30 trillion human cells

Interestingly, most of our cells lack a nucleus:
☞ 84% are red blood cells
☞ 5% are platelets

ncbi.nlm.nih.gov/pmc/articles/P…