Renal Flashcards
Alcoholic presents with Na+ - 110 plasma osmolarity - 265 Cortisol - WNL No edema, cyanosis etc. dx?
SIADH
High ADH causes water retention leading to hyponatremia and decreased plasma osmolarity
Causes - pulm dz, malignancy, CNS disorders (meningitis, brain ascess, trauma)
In an alcoholic - aspiration pneumo
A pt with a hx of recurrent calcium stones (seen on XR, and elevated urine Ca2+ but NL serum Ca2+). What should be done to prevent stone formation?
HCTZ
Lowers calcium excretion by inhibiting NaCl reabsorption in the DCT. The mild volume depletion leads to increased proximal sodium reabsorption which secondarily increases passive reabsorption of Calcium
What are the effects of an ACEI?
Angiotensin II regulates vasoconstriction and release of aldosterone. It also increases GFR by constricting the efferent arteriole. This also allows for reabsorption of bicarbonate and secretion of acid
A homeless alcoholic man presents unresponsive and dry mucus membranes. Following IV fluids he has decreased urine output and flank pain. On bx - ballooning and vacuolar degeneration of proximal renal tubules, multiple oxalate crystals in tubular lumen. Pathogenesis?
Toxic renal injury proximal tubular cell ballooning and vacuolar degeneration = Acute tubular necrosis. Oxalate crystals (envelopes) = ethylene glycol poisoning (antifreeze, coolant, brake fluid) High anion gap and metabolic acidosis, tubular cats, oxalate crystals.
What is observer bias?
When investigator’s choices are affected by prior knowledge of the exposure status (ie more likely to dx diabetec nephropathy when they know a bx came from a DM pt)
How does a beta blocker affect the RAAS system?
Renin, Ag1, AgII, aldosterone, bradykinin
Decreased renin, AgI, AgII, Aldosterone
No change - bradykinin
Beta blockers block the beta 1 mediated regulation of RAAS and reduces renin activity (and therefore everything else is decreased)
At 18 wks gestation fetal U/S demonstrates unilateral hydronephrosis in a male. Where is the site of the obstruction?
Ureteropelvic junction (connection b/w kidney and ureter).
Caused by narrowing or inking of the proximal ureter
Newborns present with palpable abdominal mass
Can be due to failure of canalization or abnormal development of cirucular musculature
Which artery feeds the proximal ureter (close to its exit from the kidney)?
Renal a.
Which artery feeds the distal ureter?
Superior vesicular a.
A healthy volunteer is found to have decreased intestinal absorption of lysine, arginine, ornithine, and cysteine. If untreated, what is he at risk of developing?
Cystine Kidney stones
Cystinuria is an ar disorder that causes reduced absorption of Cysteine, ornithine, lysine, and arginine (Cola) aa’s in the intestine and kidneys (b/c they share the same transporter).
the kidneys aren’t able to reabsorb these amino acids.
RFs include low urine pH, preexisting crystal nidus, and urine supersaturation
A pt on furosemide takes high dose ibuprofen for joint pain. Blunting of the diuretic response is due to decreased production of?
Prostaglandins
Loop diuretics stimulate prostaglandin release for their vasodilatory effects (increased RBF = increased GFR which enhances drug delivery)
NSAIDs inhibit prostaglandin synthesis
What is the action of high dose IL-2 in its ability to regress malignancy?
Enhanced activity of natural killer cells
iL-2 is produced by Cd4+ to stimulate growth of CD4+, CD8+, and B cells. Also activates NK’s and monocytes. Increased activity of T cells and NK cells is responsible for IL-2’s anticancer activity
Which cytokine increases expression of MHC I and II on APC’s?
IFN-gamma
If reabsorption of a molecule is blocked in the PCT, the clearance of that molecule will be approximately be equal to the clearance of?
Inulin
During a U/S midline cystostomy which structures (besides the bladder) could be pentrated?
Anterior abdominal aponeurosis
The bladder is extraperitoneal
Which kidney structures arise from the metanephric mesoderm?
DCT Glomeruli Bowman's space, PCT Loop of Henle
What are the 3 sheets of primitive nephrotic tissues?
Pronephros
Mesonephros
Metanephros
Which kidney structures arise from the pronephros?
None. it regresses
Which kidney structures arise from the mesanephros?
Reproductive structures (Wolffian ducts, Gartners ducts)
A sexually active female presents with frequent UTI’s, cystitis, and pyelo. What is predisposing her to the pyelo?
Vesicoureteral urin reflux
Presents pathogens to the bladder due to urine returning into the ureter due to anatomic abnormality
A 7 y/o was given epi for a bee stink 2 weeks ago and is presenting with nephrotic symptoms. Dx?
Minimal change dz Inciting event can be due to infection, ummunization, or insect bite Normal LM, IF See diffuse podocyte effacement on EM Tx - corticosteroids
A pt tries to OD on diuretics. She presents with: Na - 122 K - 2.8 Cl - 84 Bicarb - 28 BUN - 22 Cr - 1.4 Ca2+ - 11.4 Albumin 3.9 What did she take?
HCTZ
Inhibits Na/Cl cotransporter in DCT
Causes hyponatremia, hypokalemia, metabolic alkalosis, and hypercalcemia
ONLY diuretic that causes hyponatremia
What would be expected in hyperacute allograft rejection?
min - hours
Recipients blood had preformed Ab against the graft
Histology - gross mottling, cyanosis, arterial fibrinoid necrosis, and capillary thrombotic occlusion
Would would be expected in acute allograft rejection?
What would be expected in chronic allograft rejection?
Months - years
Gradual decrease in allograft function (worsening HTN, progressive rise in serum Cr, proteinuria)
Low grade cellular and humoral response leads to fibrous intimal thickening leading to ischemia, atrophy of the parenchyma and tubules, and intersititial fibrosis
How do you calculate FF?
FF = GFR/RPF
RPF = RBF x (1-Hematocrit)
Because RBC’s are a portion of the RBF that are too large to be filtered
Pt presents with back pain, constipation, fatigability x months. Labs: Hgb - 8.6 MCV - 92 BUN - 68 Cr - 3.8 Total protein - 8.9 Albumin - 4.1 Bx - LM, atrophy of tubules with large obstructing intensely eosinophilic casts. Dx?
Multiple myeloma Suspect in an elderly pt with 1. fatigue (anemia) 2. Constipation (hypercalcemia) 3. Bone pain (lytic lesions) 4. Elevated serum protein (monoclonal) 5. Renal failure Myeloma cast nephropathy due to Bence Jones proteinscausein tubular obstruction and epithelial injury. Deposits = Light chain fragments
A pt on metoprolol is given an ACEI. His HTN improves but see a rise in Serum Cr. Why?
Reduction in renal filtration fraction.
ACEI can cause ARF in susceptible pts because decreased AgII means that there is less efferent arteriole vasoconstriction. This decreases GFR and therefore FF
ACEI can be detrimental in pts that rely on efferent arteriole constriction
An older pt with painless hematuria
Urinary tract cancer (urothelial or RCC)
Bx of RCC?
rounded polygonal cells with abundant clear cytoplasm. Roximal tubular epithelial cells with copious amounts of intracellular glycogen and lipids. Staining usually dissolves glycogen leaving clear psaces on bx.
Where would you expect to see the lower tubular fluid osmolarity in the nephron?
DCT
thick ascending loop
42 y/o man with T1DM presents with frequent involuntary loss of urine, difficulty maintaining stream, and nocturnal enuresis
Overflow incontinence Impaired detrusor contractility or bladder outlet construction. Increased postvoid residual volume T1DM affects detrusor muscle inn Dx with U/s or cath
During surgery a surgeon can palpate the R ureter immediately anterior to the?
internal illiac a., medial to the ovarian a.
but it would be posterior to the uterine a.
A pt recently treated for impetigo is presenting with nephrotic syndrome. What is causing his kidney damage?
Immune complexes Post streptococcal GN Type III HS reaction EM - electron dense sub epithelial humps IF - IgG and C3 +
A pt with anemia due to chronic kidney dz is given a erythropoiesis stimulating agent. What complication is most likely to be seen when this agent is used?
Worsening HTN
Increased risk of thromboemolic events
But, it does allow pts to avoid transfusions
Unilateral kidney atrophy is suggestive of?
Renal a. stenosis
Occurs in elderly with atherosclerotic changes or in women of childbearing age with fibromuscular dysplasia
Often presents with HTN and abdominal bruit
10 y/o presents with tea-colored urine after exercise, HTN, and periorbital edema. Urinalyusis = RBC casts and mild proteinuria. Dx?
Post-infectious GN
Following exercise pt has muscle pain, elevated creatine kinase, myoglobinuria (but not RBC’s). Dx?
Rhabdomyolysis
A young pt presents with recurrent kidney stones and hexagonal crystals are found on urinalysis. Dx?
Cystinuria
Defect in dibasic amino acid transport causes hexagonal cysteine stones.
Sodium cyanide-nitroprusside test can detect excess cystine in the urine
Tx - hydration and alkalinize the urine (acetazolamide)
Differential for a pt with crescent formation on renal bx
- anti-GBM RPGN )Goodpastures)
- Immune complex RPGN - (lympy bumpy, PSGN, SKE, IfA nephropahty, Henoch-Schonlein purpura)
- Pauci-immune RPGN - ANCA (granulomatosis with polyangiitis or microscopic polyangiitis)
A pt presents with heamturia, fatigue, nasal congestion x months. PE = edema. Labs = elevated BUN and serum Cr. Urinalysis = moderate proteinuria, hematuria with RBC casts. Bx = crescentic glomeruli. IF = no immunoglobulin or complement deposits
Crescentic formation with no Ig or complement deposits = pauci-immune GN
Dx - ANCA Abs
Either granulomatosis with polyangiitis or microscopic polyangiitis
Can be idiopathic
Why do pts with MS develop urge incontinence (sudden urge to urinate)?
Loss of central nervous system inhibition of detrusor contraction in the bladder.
As the dz progresses, the bladder can become atonic and dilated, leading to overflow incontinence
A 12 year old immigrant has HTN but asymptomatic. U/S reveal dilated calyces with overlying cortical atrophy bilaterally mostly in the upper and lower poles. Dx?
Reflux nephrophathy
Caused by retrograde urine flow from the bladder to ureter. Hydrostatic pressure of the refluxed urine and infections causes inflammation.
Papillae in the upper and lower poles are most susceptible to reflux-induced damage and appears as dilated calyces with overlying renal cortical scarring
Obese woman presents with peripheral edema and proteinuria. Serum contains IgG4 ab to the phopholipase A2 receptor (PLA2R), a transmembrane protein abundant on podocytes. Dx?
Membranous Nephropathy
Idiopathic membranous nephropathy is associated with circulating IgG 4 Ab to the phospholipase A2 receptor, which might play a role in the development of dz
Which part of the kidney is injured in acute tubular necrosis?
Proximal tubules and thick ascending loops of Henle in the outer medulla are the most sensitive.
ATN is caused by decreased renal perfusion due to severe hypovolemia, shock, or surgery.
Muddy brown casts
17 y/o presents with occasional bloody urine that follows a flu like illness. Nephritic urinalysis. What would be seen on bx?
Mesangial deposition of IgA
IgA nephropathy (Berger dz) presents as recurrent self-limited painless hematuria within 5 days after a UR. Bx = mesangial IgA deposits on immunofloresence
Vs PSGN that would be seen 1-3 weeks after strepotcoccal pharyngitis and is not usually recurrent
What changes are seen in:
Rening, AgI, Ag II, aldosterone, bradykinin after a pt initiates an ACEI?
Increased: renin, Ag I, Bradykinin
Decreased: Ag II, aldosterone
Don’t forget that ACE also breaks down bradykinin
A 67 yo man presents with weakness, fatigue, anorexia, and intermittent nausea x months and also notes itching. PE - bilateral edema.
Renal bx = LM demonstrated narrowing of the renal arterioles with deposition of homogenous glassy material in the subendothelial space that stains pink with periodic acid-Schiff (PAS) stain. What is the underlying condition?
Diabetes mellitus
Homogenous deposition of eosinophilic hyaline material in the intima and media of small arteries and arterioles characterizes hyaline arteriolosclerosis. This is typically produced by untreated or poorly controlled HTN or diabetes
56 y/o man with colon cancer and general edema. Urine findings are nephrotic. Bx = glomerular capillary wall thickening without an increase in cellularity. When stained with silver methenamine irregular spikes protruding from the GBM are seen. Dx?
Membranous glomerulopathy
Most common nephrotic syndrome in adults. Secondary to tumors, infection, and meds (bug, bugs, and rheum). Diffuse increased thickness of the GBM on LM without increased cellularity, “spike and dome” appearance on methenamine silver stain, and granular deposits on immunofluoresence is daignostic
During emergency hemodialysis to correct lithium overdose, blood is passed over a semipermeable membrane and allowed to equilibrate with a disalysate solution. What would increase the rate of drug removal?
Increasing surface area of the membrane
Diffusion rate across a semipermeable membrane increases with higher molecular concentration gradients, larger membrane surface areas, and increased solubility of the diffusing substance. Diffusion speed decreases with increased membrane thickness, smaller pore size, high molecular weights, and lower temperatures.
Renal cell carcinomas originate from which cell?
Epithelial cells of the proximal renal tubules.
Clear cell carcinoma is the most common kidney tumor. Easily recognizable due to high lipid content.
Gross exam - golden yello mass
LM - cells with abundant clear cytoplasm and eccentric nuclei
Why does Lithium cause nephrogenic DI?
Lithium has an antagonizing effect on the action of vasopressin on principalcells within the collecting duct system
What is the main mechanism in stone formation?
Urine supersaturation
Low-fluid intake increases the concentration of stone-forming agents. All pts with nephrolithiasis should be advised to consume lots of water.
Most common type of renal stone?
Calcium
Most common site of metastasis for renal cell carcinoma?
Lungs
Fever, maculopapular rach, and syx of acute renal failure 1-3 weeks following B-lactam abx use is highly suggestive of?
Interstital nephritis
Peripheral eosinophilia and eosinophiluira are important clues. Syx resolve after d/c the offending med
Also induced by NSAIDS, sulfonamides, rifampin, and diuretics
Presentation and lab findings of secondary hyperparathyroidism
Presents with chronic kidney dz with mineral bone dz and hyperphophatemia and decreased calcitrol. Pts can be asymptomatic or develop weakness, bone pain, and fractures.
Long term elevation of PTH (secondary hyperparathyroidism) can lead to?
Friable bone dz and osteitis fibrosa. Pts have weakness, bone pain, and fx
What urine chemistries would be expected in a pt with DKA? (pH, HCO3, H2PO4)
pH, Bicarb, and phosphate all reduced
Urinary acid excretion is primarily in the form of NH4+ and H2PO4. In metabolic acidosis the urin pH will decrease due to increased excretion of H+, NH4+, H2PO4-.
In acidodic states, which metabolite will be completely reabsorbed from the tubular fluid?
Bicarbonate
21 y/o male presents with hematuria x 2 days with passage of small blood clots. Family history of sickle cell dz. Dx?
Papillary necrosis = abrupt onset of hematuria + FHx of Sickl cell dz
Classically presents with gross hematuria, acute flank pain, and passage of tissue fragments in urine. Commonly seen in pts with sickle cell dz or trait, DM, analgesic nephropathy, or severe obstructive pyelonephritis
A pt has DI syx that is responsive to vasopressin should be dx’d with?
Central DI?
Unable to concentrate urine in response to dehydration but urine osmolarity increases following vasopressin or desmopressin administration.
Nephrogenic DI would not respond
Albumin loss in nephrotic syndrome falls into which category?
Selective
Proteinuria can be either highly or poorly selective. MCD = high selective proteinuria: mostly low-molecular weight proteins such as albumin and transferrin are excreted
Subepithelial humps on EM
PSGN RBC casts, mild hematuria LM - enlarged hypercellular glomeruli IF - granular deposits of IgG and C3 "lumpy bumpy" Look for hx of recent infection
General edema + massive proteinuria following a URI?
MCD
Most common nephrotic syndrome in kids 2-6 yrs
Effacement of podocyte foot processes
Why do pts with nephrotic syndrome develop sudden onset abdominal flank pain, hematuria, and R sided varicocele?
Renal v. thrombosis
due to hypercoagulable state caused by nephrotic syndrome.
Loss of anticoagulant factos (esp antithrombin III)
Varicoceles are typically seen on which side?
Left
Left testicular v. drains directly into left renal v.
Renal metabolism of which amino acid is most important when maximizing acid excretion?
Glutamine
Generates ammonia to be excreted and bicarb that is absorbed into the blood
Hyperacute transplant rejection is mediated by?
Antibody-mediated hypersensitivity
Recipient has anti-donor Abs
Causing mottling and cyanosis of the organ
Which artery supplies blood to the proximal (near the kidney) ureter?
Renal a.
Which part of the kidney is the main site of uric acid precipitation?
PCT or Collecting duct due to low urine pH
Suppression of endogenous flora, colonization of the distal urethra would cause infection in the?
Lower urinary tract
Vesicouretral reflux would predispose a pt for an infection in the?
Kidney (acute pyelo)
Where is the highest osmoloarity in the nephron?
The bottom of the loop of henle (deepest part of the medulla)
What are the risk factors for nephrolithiasis?
Low fluids
High oxalate, calcium, uric acid
Hypocitraturia
High urine citrate and fluids = protective
How do you calculate excretion?
(Inulin clearance x Serum concentration of X) - tubular reabsorption of X
A pt with central DI is given desmopressin. Renal clearance of which substance will decrease the most?
Urea
Desmopressing (and vaspressin) cause a V2 receptor-mediated increase in water and urea permeability at the inner medullary collecting duct. Causes increased urea reabsorption to enhance the medullary osmotic gradient to allow maximally concentrated urine
Elderly pt with low back pain takes naproxen QD. U/S reveals bilateral shrunken and irregular kidneys. Dx?
Chronic interstitial nephritis
Chronic NSAID use can lead to renal injury (chronic interstitial nephritis an papillary necrosis)
Pt has HTN due to an adrenal mass. How should he be treated?
Eplerenone, Spironolactone
Aldosterone antagonists = Conn’s syndrome (adenoma secreting aldosterone)
HTN, hypokalemia, metabolic alkalosis
Metanephric mesoderm develops into?
DCT Glomeruli Bowman's Proximal tubules Loop of Henle
A pt has a kidney rejection 1 wk post transplant due to?
Host T cell sensitization against graft MHC
Acute rejection
Where will urine have the lowest osmolarity in the nephron?
DCT
Pt with HF is put on spironolactone in order to decrease?
Hydrogen secretion from the collecting tubules
Spironolactone = aldosterone blocker
Aldosterone acts on principal and intercalated cells in the renal collecting tubules to cause reasorption of Na and water and loss of K+ and H+
Aldosterone antagonists reduce the secretion of K+ and H+ in the collecting tubule
In dialysis, diffusion rates are increased by?
Higher concentration gradients
Large membrance SA
Increased solubility of the diffusing substance
Decreases with - increased membrane thickness, pore size, high molecular weight, low temp
Following a blood transfusion a pt develops urine that is brown in color. Why?
Complement mediated cell lysis
Acute hemolytic transfusion rxn (Type II HS)
Pre-existing anti-ABO Ab bind Ag on donor RBCs. Subsequent complement activation results in RBC lysis, vasodilation and shock
Fever, hypotension, chest/back pain, hemoglobinuria
T1 DM pt is have involuntarly loss of urine. What else would be expected on PE?
Increased postvoid residual volume
Overflow incontinence due to inability to sense a full bladder and incomplete emptying
Sensation over perinum would be intact (that’s cauda equina syndrome)
In the setting of chronic hypoperfusion which cell types would be most likely to undergo hyperplasia/hypertrophy?
Modified smooth muscle cells of the afferent arteriole
Renal a. stenosis -> hypoperfusion -> activation of the RAAS system
Modified smooth muscle = juxtaglomerular cells of the afferent glomerular arterioles, synthesize renin
How do you calculate RBF when you have a pt with 50% HCT and urine flow of 1 ml/min?
RBF = (PAH clearance)/ (1-HCT) RBF = (Urine inulin x urine flow rate/plasma inulin)/(1-0.5)
How do you calculate FF when you know GFR, RBF and HCT?
FF = GFR/RPF RBF = 1 - HCT FF = GFR/(1-HCT)
Why is IL-2 supplementation useful following resection of a tumor?
Enhances NK activity
Helps to kill off the remaining tumor cells and shrink mass at sites of metastasis
IL-2 is produced by helper T cells and stimulates the growth of CD4 and CD8 and B cells
IL-2 also activates NK and monocytes.
Anticancer effect in metastatic melanoma and RCC
CMV pt becomes resistant to ganciclovir is is switched to a medication causing hypocalcemia and hypomagnesemia. What is the new drug?
Foscarnet
pyrophosphate analog . Chelates calcium to promote nephrotoxic renal magnesium wasting. Results in hypocalcemia and hypomagnesmia -> seizures
Neonate has tachypnea and hypoxia. No prenatal care. PE - flat nose and bilateral club feet. Dx?
Potter sequence (Pulmonary hypoplasia + facial and lower limb deformities)
Caused by renal agenesis
Oligohydramnios -> fetal compression and pulmonary hypoplasia
Lung hypoplasia = COD
Pt has sudden severe eye pain and ipsilateral HA and “halos” around objects. Following appropriate tx pt and increased diuresis with highly alkaline urine.
Dx
Tx
And acts on which segment of the nephron?
Dx - Acute angle-closure glaucoma
Tx - Acetazolamide (carbonic anhydrase inhibitor)
Acts on PCT - acetazolamide blocks bicarb and water reabsorption in the PCTS causing bicarb wasting.
CA inhibitors also useful in relieving intraocular pressure in open-angle and angle-closure glaucoma
MOA of lithium induced DI?
Lithium anatagonizes the effect of vasopressin on principal cells within the collecting duct system
Resolves by d/c lithium
DI is caused by antagonism or decreased release of?
Vassopressin (ADH)
Child has proteinuria and hematuria following an infection?
PSGN
Immune complex deposits (subepithelial humps)
Deposition of IgG, IgM and C3
Pathogenesis of HUS?
Kid has bloody diarrhea that resolves and a few days later presents with red urine (proteinuria and hematuria)
Caused by microthrombi in the small blood vessels (microangiopathic hemolytic anemia + throbocytopenia + acute kidney injury)
Tx of choice for DKA?
Insulin and hydration
Pt has hematuria that has been progressing over 3 months. He takes NSAIDs and used to work in a rubber manufacturing plant. Dx?
Transitional cell carcinoma of the bladder
Gross hematuria in an elderly man
RF = smoking (napthalene), occupational exposure to ruber, plastics, aromatic amine containing dyes, textiles, leather
Pt that is unable to absorb lysine, arginine, ornithine, and cysteine is at risk of developing?
Renal stones
Cystinuria, ar, unable to absorb COLA
Also decreased absorption of these aa’s from the tubular lumen
U/A - hexagonal cystine crystals
During dehydration, the majority of water reabsorption will occur in which region of the nephron?
PCT
Regardless of rehydration status the majority of water reabsorption will occur in the PCT
Following hernia repair a pt is having difficulty voiding and has post-void residual volume. Which tx should he receive?
Bethanechol (muscarini agonist)
Post-op urinary retention = decreased micturittion reflex, decreased bladder contractility, increased vesical sphincter tone
Could also use a alpha1 antagonist
Crescentic glomeruli formation is a type of?
RPGN
Consists of glomerular parietal cells, monocytes, macrophages, fibrin.
Crescent become sclerotic and disrupt glomerular fxn causing irreversible reanl injury
