Intro to Renal Medicine

Question 1

Reasons to do a renal biopsy?

Answer 1

When diagnosing PROTEINURIA, HEMATURIA, GLOMERULONEPHRITIS, RENAL ALLOGRAFT DYSFUNCTION, INTERSTITIAL PROCESSES (Sarcoidosis)

Kidney is VERY vascular (20% of the total CO!) so we want to be very careful to avoid vessel injury!

Question 2

Stains for biopsies (Light Microscopy)

Answer 2

H & E –> gold standard for pathological stains in general

Periodic Acid Schiff –> highlights BASEMENT MEMBRANE

Silver methenamine –> highlights BASEMENT MEMBRANE and IMMUNE COMPLEX DEPOSITS

Masson Trichrome Stain –> Useful in looking for FIBROSIS

Processing time for LM? 5 Hours

Question 3

What are the five categories of renal disease?

Answer 3

Vascular - diabetes, small vessel vasculitis (Takayasu, Wegener’s, Microscopic polyangitis), uncontrolled HTN, thrombotic microangiopathy, Sickle Cell, Renal artery stenosis)

Tubulointerstitial Nephritis - caused by infections, toxins, metabolic disorders, physical factors, neoplasms, immunological rxns, and hereditary diseases

Glomerular - can be Primary and Secondary

Cystic - ADPKD, ARPKD, APKD, etc.

Neoplastic - Renal cell carcinoma, Wilm’s Tumor: Nephroblastoma, Fibrosarcoma, Leiomyosarcoma

Question 4

Nephritic Vs. Nephrotic

Answer 4

Nephritic –> Associated with HEMATURIA, Proteinuria ( LESS THAN 3.5g/24hrs), active urinary sediment (RBCs, WHCs, granular cells, RBC/WBC casts)

RBC CASTS = NEPHRITIC DISEASE!

Nephrotic! HIGH GRADE PROTEINURIA (> 3.5 g/24 hrs), EDEMA, HYPOALBUMINEMIA

Occasionally fatty casts, fat droplets in the sediment

Question 5

Renal Blood Flow Review

Answer 5

Aorta – renal artery – smaller arteries in lobes of kidneys – afferent arteriole – glomerulus – efferent arteriole – vasa recta OR peritubular capillaries – renal vein – inferior vena cava

Question 6

Review of Urine Production

Answer 6

The glomerular tufts filter blood through a basement membrane that keeps out protein by
being negatively charged and is covered by podocyte foot processes. This filtrate travels through the proximal tubule, then the loop of Henle where it is concentrated because of an osmotic difference
between the lumen of the tubule and the interstitum. The filtrate then travels to the collecting ducts –
drains to papilla of pyramids – calyx – renal pelvis (in the hilus) – ureter.