Kidneys
The kidneys are both important and difficult. Let's break the kidney down into fundamental blocks. 90% of the diseases covered on your test will fall into one of these blocks. The other 10% consists of some congenital problems and nephrotoxic medications.
The only other weird thing about the renal system is the electrolytes. The electrolytes are an important topic for both boards and wards. And they often get thrown in with the kidneys because the nephron is responsible for regulating them.
Here’s another big picture framework.
Azotemia - elevated BUN and Cr
AKI - Acute Kidney Injury
ATN - Acute Tubular Necrosis
AIN - Acute Interstitial Nephritis
APSGN - Acute Post Streptococcal Glomerulonephritis
DPGN - Diffuse Proliferative Glomerulonephritis
CKD - Chronic Kidney Disease
ESRD - End Stage Renal Disease
MCD - Minimal Change Disease
FSGN - Focal Segmental Glomerulonephritis
MN - Membranous Nephropathy
MPGN - Membranoproliferative Glomerulonephritis
AFFERENT & EFFERENT ARTERIOLES
Regulators
The Afferent and Efferent Arterioles are the vessels connected to glomeruli. They play a critical role regulating our fluid levels. They lie at the intersection of the RAAS system, the natriuretic peptides, the sympathetic system and prostaglandins. I can’t emphasize enough how important they are.
MALIGNANT HYPERTENSIVE & DIABETIC NEPHROPATHY
Onions yummy
Diabetes and hypertension will strangle your kidneys if given enough time. They achieve this by transforming the blood vessels that travel to the kidney. They narrow the lumens by thickening the arterial walls, and this chokes off the blood flow. There are a couple of different ways that they can fatten the walls, and the USMLE thinks it's important that we recognize these images, particularly the onion-skinning one. When the kidneys begin to notice that they’re receiving less blood than usual, they respond by turning on the RAAS system. This jacks up the blood pressure further. It’s a vicious cycle. You can stop this vicious cycle by blocking RAAS with ACE Inhibitors or ARBS. I think the point that the USMLE wants to convey is that we should know why diabetes and hypertension hurt our kidneys.
I define Malignant Hypertension as “fucking awful blood pressure for decades.” I want you to think in the 170+ systolic range. Every day. For 20 years. These patients often refuse to take their hypertension drugs or haven’t seen a doctor in decades.
ENDOCRINE KIDNEY
The kidney makes a lot of interesting molecules
