Three Things Today

A guy back home told me that if I can aim to learn and retain three new things in medicine each day, then I'll be good to go. That doesn't seem like much at first, but it would mean that over the course of a year, 1095 new concepts would be "mastered" and committed to memory.

#1: Mechanism of Anemia in Infective Endocarditis (IE)

So we're just wrapping up a four week cardio block with a look at valvular heart disease. One of the things that IE can present with is anemia. We weren't sure of the mechanism behind this form of anemia. Someone in my PBL group suggested that the pathogen (Strep viridans, Enterococcus, Staph aureus, Staph epidermidis, HACEK orgs, Candida, or other G -ves) attacked the red blood cells, resulting in a hemolytic anemia. But when I thought about it, it seemed like there weren't too many pathogens that routinely infect red blood cells. There are a couple parasites I know of (Plasmodium spp in malaria and some Mycoplasma bacteria) and a mention of hookworm in Robbins that infect RBCs, resulting in hemolytic anemia.

It looks like bacterial endocarditis falls under the impaired RBC production in anemia of chronic disease. This is what Robbins had to say:

1) Low EPO.
Chronic inflammatory state results in release of many cytokines (particularly IL-1 and TNF from macrophages and IFN-gamma from Th1 cells) that reduce renal EPO generation. They also stimulate hepcidin synthesis in the liver --> inhibits release of iron from storage (ferritin). This leads to...

2) Reduced serum iron. There is high ferritin iron storage but low serum iron and reduced TIBC suggesting a problem in getting iron from storage to erythroid precursors in the bone marrow. Lack of iron --> Fe deficiency. May mimic Fe deficiency anemia (hypochromic and microcytic) but the high serum ferritin and low TIBC rule out Fe deficiency as the 1º cause.

I read some stuff from Google about decreased RBC half-life and some effects of cytokines directly on the bone marrow. Not sure how reliable those sources are...

#2: Polycystic Kidney Disease

So last thursday during my clinical bedside coaching, I got pimped out pretty badly. My preceptor (a registrar) was running a bit late so she had one of the registered medical officers (RMOs) on her team take us around to see the patients. Thus began one of the longest GI exams ever, during which my preceptor came back and I got tag-teamed drilled for what seemed to be like an eternity of questions that I had no answers to. Some I should have known the answer to - like guessing that his abdominal bruising was from his enoxaparin if I had known that he had been in hospital for a long time. Others I had never even heard of doing before like auscultating for splenic infarcts or hepatocarcinomas. Didn't realize you could actually hear a carcinoma...

Pimper: "What else would you listen for?"
Pimped (me): "Other than bowel sounds? umm...renal bruits?"
Pimper: "No"
Me: "Uh...check the aortic bifurcation for bruits?"
Pimper: "No, this is a GI exam"
Me: "Uh...i'm not sure."
Pimper: "What did you just do earlier?"
Me: "I palpated for his liver, spleen, and kidneys."
Pimper: "So...what would you listen for?"
Me: "Uh...I don't know"
Pimper: "You need to listen for splenic infarcts and hepatocarcinomas."
Me: "Oh...what do they sound like?"
Pimper: "They sound like friction rubs"
Me: "Okay..."

One thing that I should have known was that a top differential for a palpable kidney is polycystic kidney disease. I found out that there are two forms. The adult version is the most common (accounts for 5-10% of chronic renal failure) and is autosomal dominant whereas the autosomal recessive (childhood) variant is rare and often presents perinatally. The more you know...

#3: Chest X-ray in Left Heart Failure

Doing some revision, I came across a nice little mnemonic to help with remembering what you would find on a CXR in LHF. It's as simple as ABCDE!

Alveolar Edema
Kerley B lines
Cardiomegaly
Dilated prominent upper lobe vessels
Pleural Effusion


Hopefully, blogging this stuff will help it stick to my long-term memory...

Figure 1. Me in my small group room looking super impressed with the fact that I need to basically memorize Talley and O'Connor cover to cover so that I don't get pimped out so badly next week...