Renal Flashcards
What are the 3 stimuli for renin release?
- Beta adrenergic stimulation
- Low sodium in the DCT (sensed by macula densa cells)
- Low renal arterial bp (sensed by JG cells)
What’s the equation for renal clearance?
CL=U*V/P
U=urine concentration of substance
V=urine flow rate
P=plasma concentration
How do we estimate GFR?
Clearance of inulin (UV/P)
What’s going on if the clearance of a substance is less than the GFR?
Substance is being reabsorbed by the tubules
What’s occurring if the clearance of a substance is more than the GFR
Substance is being secreted into the tubular lumen
What is a normal GFR?
~100ml/min
Does creatinine clearance overestimate or underestimate GFR?
Slightly overestimates GFR bc a little bit of creatinine is secreted from the tubules
What is PAH clearance used to estimate?
Renal plasma flow
CL of PAH
Why is PAH used to estimate RPF?
PAH is freely filtered and secreted.
All the PAH going to the kidney will be excreted!
What’s the equation for Filtration fraction?
FF=GFR/RPF
- GFR estimated with creatinine clearance
- RPF estimated with PAH clearance
What’s a normal FF?
20%
how do prostaglandins affect the GFR and RPF?
PG dilate the afferent arteriole, which will increase the RPF and GFR
What is the effect of NSAIDs on the GFR and RPF?
NSAIDs will block PG synthesis, leading to vasoconstriction of the afferent arteriole. This would decrease the GFR and RPF
Do NSAIDs affect the FF?
No, GFR and RPF are both decreased equally, so the FF would be the same
What is the effect of Angiotensin II on the glomerulus?
Angiotensin II preferentially constricts the Efferent arteriole. This creates a backpressure that will lead to increased GFR but decreased RPF (increased FF)
How do ACE inhibitors affect FF?
ACEIs inhibit the formation of AngT II, so this would lead to a vasodilation of the efferent arteriole. This would increase RPF but decrease GFR, leading to a Decreased FF
What’s the equation for filtered load of a substance?
FL=GFR*P
Equation for Excretion rate?
Excretion rate=U*V
How do you determine how much of a substance was reabsorbed?
filtered-excreted
How do you determine how much of a substance is secreted?
Excreted-filtered
Is glucose filtered?
Glucose and amino acids are freely filtered but reabsorbed by the renal tubules
How is glucose reabsorbed in the renal tubules?
Na/Glucose co-transporter in the PCT
How are amino acids reabsorbed?
Na cotransport
-There are separate transporters for neutral, positive and negative amino acids
Deficiency of transporter for neutral AAs. Leads to an inability to make niacin bc no tryptophan
Hartnup dz
inability to make niacin:
“3 D’s of pellagra”
-Dermatitis, Diarrhea, Dementia”
What substance is required for active secretion of anions in the PCT?
alpha-ketoglutarate exchanged for anions on the basolateral membrane. The anion is then secreted into the lumen
Which part of the loop of Henle is responsible primarily for water reabsorption?
Thin descending limp is impermeable to Na, so lots of water reabsorption occurs here
What is the thick ascending limb primarily impermeable to?
Water
What are 3 important points to remember about the thick ascending limb?
- Impermeable to water
- Ca and Mg are reabsorbed here
- Na/2Cl/K symporter is inhibited by loop diuretics
How does PTH increase Calcium levels?
Stimulates bone resorption
Stimulates kidneys to activate vitamin D
Stimulates kidneys to reabsorb more Ca (DCT)
Which diuretic is used to treat acute glaucoma?
Mannitol
Which diuretic is used to treat chronic glaucoma?
Acetazolamide
Drug class: Triamterene
K sparing diuretic
Drug class: Acetazolamide
Carbonic anhydrase inhibitor
Drug class: Hydrochlorothiazide
Thiazide diuretic
Drug class: Bumetanide
Loop diuretic
Drug class: Spironolactone
K sparing diuretic
Drug class: Chlorothiazide
Thiazide diuretic
Drug class: Ethacrynic acid
Loop diuretic
Drug class: Mannitol
Osmotic diuretic
Drug class: Metolazone
Thiazide diuretic
Drug class: Chlorthalidone
Thiazide diuretic
Drug class: Furosemide
Loop diuretic
Drug class: Amiloride
K sparing diuretic
Drug class: Torsemide
Loop diuretic
What are the diagnostic criteria for Nephrotic syndrome?
Proteinuria >3.5g/day
Hypoalbuminemia
Peripheral edema
Glomerular histology reveals multiple mesangial nodules. This lesion is indicative of waht dz?
Diabetic nephropathy
-Kimmelstiel-Wilson nodule
Kid presents with episodes of gross hematuria and high-frequency hearing loss. What’s the dz?
Alport syndrome
-“Can’t see, can’t pee, can’t hear high C”
Linear pattern of IgG deposition on Immunoflourescence?
Goodpasture syndrome
-Anti-GBM antibodies
Lumpy-bumpy deposits of IgG, IgM and C3 in the mesangium
Poststreptococcal glomerulonephritis
Deposits of IgA in the mesangium
IgA nephropathy
Anti-GBM antibodies, Hematuria, hemoptysis
Goodpasture syndrome
Nephritis, deafness, cataracts
Alport syndrome
Crescent formation in glomeruli
Rapidly progressing GN
Wire loop on LM
Lupus nephritis
MC nephrotic syndrome in children
Minimal change dz
MC nephrotic syndrome in adults
Focal segmental glomerulosclerosis
Kimmelstiel-Wilson lesions (nodular glomerulosclerosis)
Diabetic nephropathy
EM: effacement of podocyte foot processes
Minimal change dz
Nephrotic syndrome associated with Hep B
Membranoproliferative GN
Nephrotic syndrome associated with HIV
Focal segmental glomerulosclerosis
EM: subendothelial humps and tram-track appearance
Membranoproliferative glomerulonephritis
LM: segmental sclerosis and hyalinosis
Focal segmental glomerulosclerosis
Purpura on the back of arms and legs, abdominal pain, IgA nephropathy
Henoch-Schonlein purpura
Apple-green birefringence with congo-red stain under polarized light
Amyloidosis
EM: spiking of the GBM due to subepithelial deposits
Membranous nephropathy
RBC cast indicates:
Glomerular damage (GN, malignant HTN, etc)
WBC cast indicates
Acute pyelonephritis
Bacterial cast indicates:
Pyelonephritis
Epithelial cast indicates
ATN, toxic ingestions
Waxy cast indicates
Chronic renal failure, low urine flow situations
Hyaline cast indicates
Normal, dehydrated
Fatty cast indicates
Nephrotic syndrom
Granular cast
Chronic renal dz, ATN
MC tumor of the urinary tract system
Transitional cell carcinoma
MC renal malignancy of early childhood
Wilm’s tumor (flank mass)
Fever, rash, hematuria, Eosinophilia
Classic presentation of Acute interstitial nephritis
