Renal Flashcards
Although only a transient structure, what is the first functional unit of the kidney to appear?
Mesonephros
What adult structures of the kidney are derived from the mesonephric duct?
Collecting ducts, calyces, renal pelvises, and ureters. All of these derive from the ureteric bud which is an EXTENSION of the mesonephros
What’s the 60-40-20 rule for remembering body fluid?
60% of total body weight is water
of that 40 would be ICF and 20 would be ECF (i.e. 2/3 is intracellular, 1/3 is extracellular)
Of the extracellular fluid, only 1/4 is plasma
What compartment is highest in Mg2+?
Intracellularly
What is the molecular pathogenesis of diabetic nephropathy?
Microalbuminuria results from non-enzymatic glycosylation of the basement membrane eliminating the normal negative charge barrier.
What will you see on glomerular histology in diabetic patients?
Kimmelstiel-Wilson nodules, ovoid or spherical lamellated eosinophilic nodules located in the peripheral mesangium. They also stain PAS+.
Aka nodular glomerulosclerosis
How would diabetic nephropathy be described on histology/path?
Glomerular basement membrane thickening
Increased mesangial matrix deposition
Kimmelstiel-Wilson nodules
What is the equation for clearance?
Cx = UxV/Px
The perfect estimate of GFR is _____, but instead we use _____.
Inulin
Creatinine, even though creatinine slightly overestimates GFR.
What is PAH used to estimate?
RPF
Kidneys receive ___% of CO at rest.
25%
Renal blood flow is approximately ___x the RPF. Why?
2x
because almost or nearly 50% of the blood flow is red cells which does not pass the glomerular BM
What is the typical filtration fraction? GFR/RPF?
Roughly 20%
Which diuretic is a carbonic anhydrase inhibitor? Where does it act and what does it do?
Acetazolamide used in the treatment of acute angle-closure glaucoma and altitude sickness
Inhibits carbonic anhydrase in the PCT preventing NaHCO3 reabsorption -> HCO3- wasting -> metabolic acidosis and alkaline urine
Which diuretic class is contraindicated in patients prone to forming kidney stones?
Loop diuretics (e.g. furosemide) due to increase Ca2+ concentrations in the urine
In these patients thiazides are a better choice
Triamterene and amiloride are K____ diuretics that act on the ____ channel in the _____.
K-sparing
Inhibit ENaC in the principal cells of the collecting tubule
What is Fanconi Syndrome?
Failure of reabsorption in the PCT -> loss of glucose and AA, HCO3-, and phosphate reabsorption most affected
What is Bartter syndrome?
Failure of reabsorption in the TAL -> hypokalemia and metabolic acidosis (like loop diuretics)
Liddle’s syndrome, which is autosomal ____ leads to increased activity of _____.
Autosomal dominant
Overactive sodium channels in the collecting duct
Why does alkalosis cause hypokalemia?
There is a K+/H+ exchanger that will push K+ into cells in order to get H+ out into the bloodstream in an effort to correct pH.
What is the mnemonic for remembering renal tubule disorders (in order from proximal tubule to collecting duct!)?
FABulous Glittering LiquidS
FAnconi - PCT
Bartter - TAL (NKCC)
Gitelman - DCT (NaCC co-transporter)
Liddle - increased ENaC
Syndrome of apparent mineralocorticoid excess (i.e. 11betahydroxy def.)
How do you calculate the anion gap? What is a normal range?
Na - (Cl + HCO3-)
Normal range = 8-12
What is the mnemonic for high anion gap metabolic acidosis?
MUDPILES
Methanol Uremia DKA Propylene glycol Iron tablets Lactic acidosis Ethylene glycol Salicylates (late)
What is the mnemonic for normal anion gap acidosis?
HARDASS
Hyperalimentation Addison disease Renal tubule acidosis Diarrhea Acetazolamide Spironolactone Saline infusion
What are the various shapes of kidney stones/crystals?
Hexagonal - cystine
Coffin - struvite/magnesium ammonium phosphate
Pyramid or dumbbell - calcium oxalate
Rectangular, diamond, or rhombus - uric acid
Elongated/wedge shaped or rosette - Calcium phosphate
What effect do ACE inhibitors have on bradykinin?
Increase, this is thought to be responsible for the ACE inhibitor-induced cough
(ACE normally breaks down bradykinin)
Abrupt onset gross hematuria in an otherwise healthy patient with sickle trait = ?
Renal papillary necrosis
Sickled cells cause obstruction of small kidney vessels -> ischemia
What is the pathogenesis of minimal change disease?
Systemic T cell dysfunction leads to the production of glomerular permeability via podocyte foot process fusion -> decreased negative charge -> selective albuminuria
(albumin is small enough to pass through slits normally and relies on the negative charge to avoid filtration)
What is the a good diuretic treatment for acute ICP or cerebral edema? What is a possible side effect?
Manitol (osmotic diuretic)
Can cause pulmonary edema, dilutional hyponatremia, metabolic acidosis, and hyperkalemia.
Which stones precipitate in alkaline urine? in acidic?
Alkaline urine =
Calcium oxalate
Calcium phosphate
Magnesium ammonium phosphate/struvite
Acidic urine =
Uric acid
Cystine
What are the first 2 lab tests in the work up of metabolic alkalosis?
Urine chloride and volume status
(differential can be initially separate on low vs high chloride and then for high chloride low vs high volume.
Poisoning with what substance can precipitate calcium oxalate stones?
Ethylene glycol
What effect does urea ADH/vasopressin have on urea reabsorption?
Activates urea transporters in the medullary collecting duct, increasing urea reabsorption.
What effect do beta blockers have on renin secretion?
Beta blockers block beta 1 receptors in the juxtaglomerular cells, which stimulate the release of renin.
Nephritic syndrome is marked by damage to the _____, while nephrotic damage is marked by damage to ____. What is the protein cut off ?
Nephritic = GBM Nephrotic = podocytes
> 3.5 gm lost per day = nephrotic
Which is an inflammatory condition: nephritic or nephrotic disease?
Nephritic, so with those you’ll see fever and other signs of an inflammatory state
Will minimal change disease show any defects on LM?
No!
“spike and dome appearance” with subepithelial deposits = ?
Membranous nephropathy
Increased pH = calcium ____ stones
Decreased pH = calcium ____ stones
inc = phosphate dec = oxalate
What is the treatment for calcium oxalate and phosphate stones (other than more fluids!)?
Thiazides or citrate
Which of the kidney stones is radiolucent (i.e. can’t be visualized on xray)?
Uric acid
How does PSGN look on immunofluorescence? On EM?
lumpy bumpy on immuno
subepithelial humps on EM
Which nephritic syndrome looks like “wire looping” on LM/EM?
Diffuse proliferative glomerulonephritis (due to SLE or MPGN)
What are the main deposits in RPGN?
Fibrin and macrophages
What type of nephritis/nephrosis is seen in Wegener’s kidney manifestations?
RPGN (crescentic nephritis)
What is IgA nephropathy/how does it present?
Most common cause of glomerulonephritis
Often affects older children/young adults
Painless hematuria 5-7 day after URI -> often subsides but returns with subsequent URIs
Mesangial hypercellularity
Mesangial IgA deposits
What are the symptoms of the 3 phases of ATN?
Initiation: ischemic injury to renal tubules precipitated by hemorrhage, acute MI, sepsis, surgery, etc.
Maintenance: decreased urine output, fluid overload, increasing creatinine/BUN, hyperkalemia, metabolic acidosis (retention of hydrogen and anions)
Recovery: Gradual inc in urine output -> high vol diuresis. Hypokalemia, Hypomagnesia, hypophosphatemia, and hypocalcemia due to slowly recovering tubular function
Where do JG cells reside?
In the wall of the afferent arteriole. JG cells themselves are actually modified smooth muscle cells.
What two buffers seen in the urine are used to excrete acid?
NH4+ (due to extra NH3 production)
H2PO4- (due to extra HPO4)
If urine osmolarity is >500, what kind of AKI do you have?
Prerenal
Osmolarity will be decreased (<350) in intrarenal and postrenal AKI
High BUN/Cr ratio (i.e. >20) = ___renal AKI
prerenal
BUN/Cr ratio <15 = ___renal AKI
intrarenal
What is AIN/how does it present?
Hypersensitivity reaction to drug (usually 1-2 weeks after starting it) -> interstitial inflammation
Marked by pyuria + eosinophils!
Diuretics, penicillins, sulfonylureas, rifampin, NSAIDs, are all especially common offenders
Patients in the maintenance phase of ATN have oliguria and are thus at risk for what metabolic abnormalities?
Hyperkalemia
Metabolic acidosis
Which diuretic can cause calcium wasting?
Loop diuretics (e.g. furosemide)
What cell type becomes malignant in renal (clear) cell carcinoma?
Epithelia of proximal convoluted tubules
What complications can result from BPH?
UTI
Bladder hypertrophy
Hydronephrosis
CKD
Recurrent pyelonephritis can lead to _____.
Renal scarring
