Renal Exam 1 Flashcards
Location of kidneys in comparison to vertebral bodies and ribs
- Between vertebral bodies T12-L3
- Anterior to ribs 11/12
Contents of renal corpuscles
- Glomerulus (tuft of capillaries) and Bowman’s (glomerular) capsule
Contents of cortical labyrinth
- PCT, Loop of Henle, DCT
Contents of renal medulla
- Loop of Henle, collecting ducts, papilla. Note: no glomeruli
Define arterial supply to kidneys and subsequent divisions
- Renal = interlobar = arcuate = interlobular = afferent arteriole = efferent arteriole = peritubular capillary beds = vasa recta (specifically at Loop of H) —- venous (reversal of names)
Describe layers that make up the renal corpuscle from area of capillaries out
- Blood lumen
- Fenestrated endothelium
- Basement membrane (glomerular basement membrane): lamina rara, densa, rara
- Podocytes (visceral layer of Bowman’s) with pedicels that interdigitate. Slits between each process.
- Urinary space
- Parietal layer of Bowman’s
Function of mesangial (aka intraglomerular mesangial) cells
- Contractile: control GFR
- Phagocytic: clear immune cell complexes, clean BM
Function of glomerular BM
- Lamina rara: negatively charged (heparin sulfate) traps cationic molecules and repels anionic
- Lamina densa: composed of collagen type IV, restricts movement of molecules greater than 70 Kda
Describe flow of filtrate (ultimately urine) starting at glomerulus
- Glomerulus = PCT (proximal convoluted tubule) = descending Loop of Henle = ascending Loop of Henle = DCT (distal) = collecting duct = papillary duct (many collecting ducts converge on these) = renal papillae (many papillary ducts converge on these) = minor calcyx = major calyx = renal pelvis = ureters = bladder = urethra
Compare and contrast between epithelium of PCT, descending Loop of Henle, ascending Loop of Henle, DCT, collecting tubules/ducts and calyces / renal pelvis
- PCT: low simple columnar (to cuboidal) epithelium w/microvilli (brush border) d/t need for resorption
- Descending Loop (thick walled): simple cuboidal transitioning to simple squamous
- Ascending Loop (thin walled): simple squamous
- DCT: low simple columnar (to cuboidal) epithelium. Note: no brush border.
- Collecting tubules/ducts: simple cuboidal epithelium
- Calyces (minor/major) and renal pelvis: transitional epithelium
Location of JGA (juxtaglomerular apparatus)
- Adjacent to DCT and afferent arteriole
Contents and function of JGA
- JGA refers to: macula densa, JG cells, lacis cells
- Overall: regulates BP and GFR
- Macula densa: cells contained within DCT at vascular pole that sense NaCl concentration in filtrate
- JG cells: cells at vascular pole, release renin
- Lacis cells (aka extraglomerular mesangial cells): cells at vascular pole, resemble smooth muscle cells, play role in blood flow regulation
Where is macula densa always located in kidney?
- At vascular pole of glomeruli
Define normal constriction of ureters where kidney stones may become lodged
- Junction of renal pelvis with ureter
- Where ureters cross pelvic brim
- Junction of ureter into urinary bladder as it enters infero-medially where a flap valve is created preventing backflow of urine into ureter
In what pelvis does bladder lie?
- Lesser pelvis (aka true pelvis)
Epithelial lining of bladder
- Transitional epithelium
Where is internal urethral sphincter muscle located?
- Within neck of bladder
Innervation of detrusor muscle
- Detrusor = smooth muscle in walls of blader
- Innervation = PSNS
Describe micturition reflex and what controls it
- Mnemonic = store and pee
- Store: SNS increases tone of internal urethral sphincter in neck of bladder allowing for storage
- Pee: PSNS relaxes/inhibits internal urethral sphincter in neck of bladder allowing for peeing
- Somatic involvement of this reflex is present. Specifically through pubococcygeus muscle of levator ani. This muscle controls angle of neck of bladder with the urethra and provides voluntary control of urination together with external urinary sphincter muscle.
Parts of male urethra
- Intramural (pre-prostatic): neck of bladder surrounded by internal urethral sphincter muscle
- Prostatic
- Membranous: w/external urethral sphincter
- Spongy (penile)
Narrowest and least distensible part of male urethra
- Membranous
Innervation of external urethral sphincter muscle? Function?
- Pudendal nerve
- Voluntary urination
Difference between male and female internal urethral sphincter muscle
- Females: not as well organized
Location of visceral afferent fibers conveying pain sensation from urinary system
- T10-L2 via DRG
Where is referred pain for kidney stones that pass through ureter
- Loin to groin (ipsilateral lower quadrant of anterior abdominal wall to groin)
List the major functions of the kidney
- Excretion of metabolic waste products and foreign substances
- Regulation of body fluids and electrolyte balance, acid-base balance and arterial BP
- Elaboration of endocrine hormones (EPO, final step in activating vit D3, renin)
- Gluconeogenesis
How is the renal circulation unique in terms of circulation?
- Two capillary beds structured in series from each other: glomerular capillaries and peritubular capillaries, separated by efferent arteriole
Which nephrons assist in formation of concentrated urine?
- Juxtamedullary nephron with their vasa recta
Steps in urine formation in the kidney
- Glomerular filtration
- Re-absorption
- Secretion
- Excretion = filtration – reabsorption + secretion
Where in the nephron does the reabsorption of each of the following occur: glucose, amino acids, water, Na, Cl and K?
- Glucose: 99% reabsorbed at PCT
- Amino acids: 99% reabsorbed at PCT
- Water: PCT, descending limb, DCT and collecting duct. Not ascending limb that is impermeable to water
- Na: PCT (up to 70%)!»_space; ascending limb > DCT and collecting duct where reabsorption fine tuning is done
- Cl: PCT (up to 70%)»_space; ascending limb > DCT ??
- K: PCT (up to 70%)»_space; ascending limb. DCT and collecting duct is where secretion or re-absorption can occur.
Where in the nephron does the counter current multiplication occur?
- Loop of Henle
Where in the nephron does the counter current exchange occur?
- Vasa recta
Where in the nephron does aldosterone have its effect? What is the effect?
- Distal part of DCT which is the cortical collecting tubule at the principle cell
- Increases Na reabsorption and K secretion
Where in the nephron does ADH have its effect? What is the effect?
- Collecting tubule
- Increase permeability of collecting tubule to water = increase water reabsorption and less H2o excreted
Describe renal control of acid-base balance
- HCO3- excretion leads to bases being removed from blood.
- H+ are secreted into lumen by epithelium of tubule leading to acid being removed from blood.
- If more H secreted than bicarb filtered, net loss of acid. If more bicarb filtered than H secreted, there will be net loss of base
- Alkalosis: kidney will not re-absorb filtered bicarb increasing bicarb excretion leading to production of more bicarb and proton to drive acid production
- Acidosis: kidney re-absorbs filtered bicarb decreasing excretion leading to drive that reduces acid accumulation
Explain forces governing glomerular filtration and tubular reabsorption
- Net filtration pressure = sum of hydrostatic forces/pressure and colloid osmotic forces/pressure = glomerular hydrostatic pressure – Bowman’s capsule pressure – glomerular oncotic pressure. Note: glomerular hydrostatic pressure favors filtration while glomerular colloid osmotic pressure and Bowman’s capsule pressure oppose filtration.
- Glomerular capillary filtration fraction coefficient (three layer barrier between the blood lumen and the urinary space)
Explain the effect of size and charge on the glomerular filtration. How does this change when a disease process causes the loss of the filtration barrier of the glomerulus?
- Negatively charged BM impedes movement of both negatively charged and large (> 70 Kda) substances including proteins into glomerular filtrate. Increased permeability leads to protein entry into filtrate. This is seen in nephrotic syndrome. Proteinuria = reduced colloid oncotic pressure = edema and reduced plasma volume.
How is GFR affected by vasoconstriction of afferent arteriole? Vasodilation?
- Vasoconstriction = decreased GFR
- Vasodilation = increased GFR
How is GFR affected by vasoconstriction of efferent arteriole? Vasodilation?
- Vasoconstriction = increased GFR
- Vasodilation = decreased GFR
Ability for kidney to form urine that is more concentration than the plasma is essential for survival of mammals on land. What are the requirements for this?
- High osmolarity of renal medullary interstitial fluid
2. High level of ADH
Describe mechanisms for producing a hyperosmotic renal medulla
See SG for explanation
Describe how ADH is released
- ADH: Increase in fluid osmolality surrounding osmoreceptors in hypothalamus leads to them shrinking. Shrinkage signals supraoptic nuclei to release ADH (posterior pituitary).
Describe mechanisms for release of renin
- Baroreceptor: increased pressure in afferent arteriole inhibits renin release, decreased pressure promotes renin release
- SNS: beta-1 adrenergic nerves stimulate renin release
- Macula densa: increased NaCl in distal nephron inhibits renin release; decreased NaCl promotes renin release
Function of renin downstream
- Renin cleaves angiotensinogen into ang I
- Ang I is converted into ang II via ACE
- Ang II: vasoconstriction, renal retention of salt & water and stimulates aldosterone release
Effect of increased renal SNS nerve activity
- Reduction in GFR by constriction of renal arterioles
- Increase in tubular Na reabsorption
- Increase in renin release
Why do we care about renal clearance?
- Quantifies the excretory function of the kidneys.
How is GFR measured?
- GFR = [Vdot x U(x)] / P(x)
- Vdot = urine flow rate
- U(x) = urine concentration of X
- P(x) = plasma concentration of X
Explain why the clearance of creatinine is a reasonable estimate of GFR. Is Cr absorbed or secreted?
- Creatinine is cleared almost entirely by glomerular filtration. Cr is freely filtered with a small amount secreted, so calculation is a slight over-estimation.
Explain why clearance of PAH (para-amino hippurate) is a measure of effect renal plasma flow rate.
- Renal plasma flow: if substance is completely cleared from plasma, the clearance rate of that substance is equal to the total renal plasma flow
- RPF = [U(s) x V] / P(s)
- Waiting for Di Sole
What is filtration fraction? Calculate FF if given GFR and RPF. The FF is usually about what percentage of the renal plasma flow?
- FF = fraction of RPF that is filtered into Bowman’s capsule at glomerulus.
- FF = GFR / RPF.
- FF is usually about 20% of GFR
Which factors are needed to calculate a patient’s GFR using Cockroft-Gault formula. What factors are needed to use the modification of diet in renal disease (MDRD) study formula for calculating GFR?
- Cockcroft-Gault: Age, body weight, plasma creatinine, gender
- Equation Ccr = (140 – Age) x body weight (kg) / 72 x Pcr (mg/dl). Multiply x 0.85 for females. - MDRD: Plasma creatinine, age, AA, gender
How can abnormalities in kidney function cause HTN?
- Increase vascular resistance, decreased glomerular capillary filtration fraction coefficient, excessive tubular sodium re-absorption
Causes and effects of AKI (acute kidney injury)
- AKI = sudden decrease in kidney function or damage (few hours or days) indicated by rapid decline in GFR
- Causes:
a. Pre-renal: kidney hypoperfusion
b. Renal: vascular, glomerular, tubular or interstitial problems
c. Post-renal: UT obstruction - Effect: water/hypernatremia (edema, HTN), hyperkalemia, metabolic acidosis, anuria
Define chronic kidney disease (CKD).
- Progressive and irreversible loss of large number of nephrons. Clinical sx appear until nephrons fall to 75% below normal.
Three ways which body can regulate pH. Over what time frames does each operate?
- Bicarbonate buffer system: almost instantaneous
- Respiratory compensation: regulates PCO2 in matter of hours
- Renal compensation: regulates bicarb concentration and H excretion in matter of days
Define Henderson-Hasselbach equation to determine pH in the body
- pH = 6.1 + log[(HCO3-)/0.03PCO2]
What effect does normal metabolism have upon acid-base balance?
- Oxidation of nutrients generates CO2
- Oxidation of methionine/cysteine and other sulfur-containing compounds generate sulfuric acid
- Phosphate-containing compounds are consumed that form phosphoric acid
- Metabolism of glutamate and aspartate forms bases
Do protons leave the body as free H? Explain.
- Cannot leave as free H d/t limiting urine pH. Removed by binding to HPO4- (leaves as H2PO4) and NH3 (leaves as NH4+)
How are hydrogen ions secreted into tubular lumen?
- Proximal acidification: PCT
- Na/K ATPase sets up energy gradient. Na/H secondary active antiporter moves H out into tubular lumen and Na comes back in. - Distal acidification: DCT and collecting ducts
- Low pH stimulates insertion of H/ATPase into luminal membrane, which moves H out into tubular lumen.
Describe the reabsorption of bicarbonate.
- Virtually all reabsorbed (90% in PCT, 10% in collecting duct)
- Proximal tubule: H+ in tubular lumen reacts with HCO3- to form H2CO3, which is broken down by carbonic anhydrase into water and CO2. These enter into tubular cell where they are formed back into H2CO3 via another carbonic anhydrase isoform. They dissociate into HCO3- and H+. HCO3- moves back into peritubular capillary with Na via symporter. Note: Na entered from tubular lumen via Na/H antiporter. Net = movement of NaHCO3 from filtrate to blood.
- Collecting duct: Same as above (except H+ present in tubular lumen d/t H/ATPase). HCO3- exits renal tubular cell via HCO3-/Cl- antiporter.
Is bicarbonate always reabsorbed? Can it be excreted?
- In metabolic alkaloses, bicarb can be actively secreted. This is accomplished by B-type intercalated cells of collecting duct.
- Here, the cell reverses the polarity of the H/ATPase and bicarb/Cl antiporter to peritubular and tubular lumen respectively. Now proton reabsorbed into peritubular capillary and bicarb excreted.
Why does excretion of free H make a minimal contribution to pH regulation? What is meant by limiting urine pH?
- H/ATPase stimulated by high acid load can raise the proton concentration in filtrate to a max vaue of 0.04 mmol/L, corresponding to urine pH of 4.4. At this pH, the transporter is inhibited. This is referred to as the limiting urine pH. The daily acid load is much higher than what can be eliminated using this method. Excretion of proton takes place therefore by H2Po4 and NH4+.
What is the role of phosphate in the excretion of H ions? Explain how this works.
- Filtered HPO4- binds to proton and is excreted in urine. Each time this occurs, one H+ is eliminated and one new HCO3- is formed and added to blood. This corrects as acidosis.
Define titratable acid and describe how it is measured.
- Titratable acid is the measure of protons excreted in urine as un-dissociated weak acid. The most abundant one is H2PO4.
- Measured: Do 24 hr urine collection, measure amount of NaOH required to back-titrate urine pH to 7.4.
What is the role of NH4+ in the excretion of H ions? How are glutaminase and glutamate DH involved in this process?
- NH4+ is a means to remove proton from the body in response to severe acidosis.
- Glutamine converted to glutamate via glutaminase, which generates NH4+. Glutamate is converted to alpha-ketoglutarate by glutamate DH, which yields a second NH4+. When H+ combines with NH3 and excreted as NH4+, HCO3- is released to the blood. Net effect = 2 HCO3- added to blood.
What regulates the rate of H secretion by renal tubular cells?
- pH dependent
- Low pH activates Na/H antiporter and H/ATPase
List what happens in kidney during acidosis
- H+ secretion increases, all bicarb reabsorbed, titratable acid excreted in form of H2PO4, NH4+ production/excretion increased
List what happens in kidney during alkalosis
- HCO3- secreted in urine via B-type intercalated cells of collecting duct
Normal lab values for arterial PCO2, arterial pH, arterial bicarb, urinary titratable acid, urinary ammonium ion
- Arterial PCO2: 40 torr
- Arterial pH: 7.35 – 7.45
- Arterial bicarb: 24 mmol/L (rarely measured)
- Urinary titratable acid: 0-20 mmol/day. Up to 40 seen in acidosis
- Urinary ammonium ion: 20-40 meq/day. Upon to 250 seen in acidosis
Define anion gap. How is it calculated? What conditions might produce a large anion gap?
- Difference between primary measured cations and anions in serum. Commonly performed in patients who present with AMS, unknown exposures, acute renal failure and acute illnesses.
- Calculated: [Na plasma] – [Bicarb plasma] + [Cl plasma]
- Normal = 8-12 meq/L
- Large gap d/t ingestion of production of fixed acid
Define base deficit.
- Difference between measured bicarb concentration and bicarb concentration predicted by normal buffer slope at that pH given buffering/compensation.
View cases from L5
View cases from L5
Who are more at risk for urolithiases?
- Men, elderly until age 60, history
Primary CT signs of ureteral obstructions d/t stones
- Stone seen in ureter on symptomatic side, inspected along course, with soft tissue rim sign (ureteral wall edema surrounding stone)
Secondary CT signs of ureteral obstructions d/t stones
- Perinephric stranding (edema): non-crisp kidney border, collecting system dilation, ureteral dilation, nephromegaly, decreased enhancement
What is the first line choice in workup of flank pain suspicious for urinary calculi?
- Non-contrast CT
- US appropriate in pregnant population
First line imaging test in patient with unexplained hematuria or renal dysfunction
- Ultrasound
Major method for imaging and characterizing cystic and solid renal lesions
- CT w/ and w/o contrast
Most common renal mass
- Simple cyst
Does CT or US have better sensitivity for detecting solid mass?
- CT. 95% compared to 77%
Define attenuation. Define enhancement?
- Attenuation: Decrease in intensity of x-ray beam caused by absorption of photons in tissue. Air (very black)
How do you differentiate between a complicated cyst in the kidney vs a renal cell carcinoma?
- Can be indistinguishable
US is most cost effective method of defining and confirming a benign cyst. What are the properties of a simple cyst on US?
- Sonolucent (aka anechoic), demonstrates enhancing through transmission, thin/almost imperceptible wall
Properties of a simple cyst on CT
- HU
Features that makes a cyst non-simple?
- Calcification, hyperattenuation on CT (> 20 HU), septations, multiloculated, nodularity, thick wall/septations (> 2mm), enhancement on CT (> 15)
Bosniak classification of cystic masses. What is management (workup / follow up)?
- I: thin walls, fluid with water attenuation, no septa, no calcifications. Benign, no imaging follow-up.
- II: benign, thin septa, fine/linear calcifications in walls/septa, minimal wall / septal enhancement is sometimes present. Almost all benign. If hyperattenuating > 3 cm, followup, otherwise no imaging f/u.
- IIF: more complex with further increase in septa and calcifications, may be thicker and more nodular, enhancement may be present but not in tissue in which calcification is present. Majority benign. May need additional imaging/followup.
- III: indeterminate for benignity or malignancy, thick/irregular walls or septa +/- calcifications, wall or septal enhancement can be clearly appreciated. Close followup, many will require surgical excision.
- IV: malignant thick irregular enhancing walls or septa containing small or large amounts of calcium, soft tissue enhancement may extend from walls or septa. Surgical excision.
Most common primary solid renal tumor
- Renal cell carcinoma. Note: increased incidence in VHL disease.
What condition are angiomyolipomas associated with?
- Tuberous sclerosis. Note: angiomyolipomas are benign.
How are renal masses characterized?
- Shape (tumefactive aka ball, infiltrative), composition, epicenter
Compare and contrast what the findings are for tumefactive vs infiltrative renal masses
- Tumefactive (aka ball): CYST, RENAL CELL CARCINOMA, angiomyolipoma, oncocytoma, metastases, abscess
- Infiltrative: infiltrating tumor (TRANSITIONAL CELL CARCINOMA, scc, lymphoma, RCC (ball-like) rarely!, metastases), infection (focal pylenonephritis), infarction
What imaging will detect fat in renal mass?
- Non-contrast CT
- US cannot always
Imaging characteristics of transitional cell carcinoma?
- Shape: infiltrative
- Composition: soft tissue
- Epicenter: renal sinus
Imaging characteristics of renal cell carcinoma?
- Shape: tumefactive
- Composition: soft tissue
- Epicenter: parenchymal
Define an adrenal incidentaloma
- Incidental adrenal mass discovered on imaging study obtained for other reasons with no overt sign of adrenal hyperfunctioning.
Risk of malignancy of adrenal incidentalomas
- 1 in 1 million w/ rate of metastatic dz 1%
- If you called every adrenal incidentaloma
Size cutoff for adrenal incidentaloma vs malignancy
- 3 cm: 95% malignant.
Describe workup of > 6cm, 3-6 cm and
- > 6 cm = surgery
- 3-6 cm = surgery biopsy or other imaging
-
Define enhancement between adenomas and malignancy/metastases
- 60% or more washout (ie. rapid washout) = adenoma
- Lower washout (ie. slow washout) = more chance of met/malignancy
- Note: generally
Best test for determining whether an incidental adrenal mass is an adenoma?
- CT scan with pre and post contrast delayed imaging
F/u of benign adrenal adenoma
- Once it is determine to be a benign adenoma without hyperfunction, forget out it. Don’t have to repeatedly image.
Types of renal congenital defects. Describe each.
- Agenesis: kidneys fail to differentiate and are absent, enlarged adrenals seen, incompatible with life if bilateral (commonly)
- Hypoplasia: failure of kidneys to develop into normal size, UNILATERAL
- Ectopic: kidney in another location, usually above pelvic brim, KINKING OR TORTUOSITY OF URETER MAY OCCUR PREDISPOSING TO INFECTION
- Horseshoe: common, increased chance for infection, compatible with life
Kidney cystic diseases
- ADPKD (Autosomal Dominant Polycystic Kidney Disease)
- ARPKD (Autosomal Recessive PKD)
- Acquired cystic disease (dialysis associated)
- Simple cysts
Mutations involved in ADPKD
- PKD1 or PKD2
What is ADPKD?
- Multiple expanding cysts in kidney that eventually destroy them by 50s when renal failure occur. It is the 4th leading cause of ESRD.
In patient with ADPKD, what else should they be checked for?
- Hepatic cysts, splenic cysts and berry aneurysms (Circle of Willis) resulting in SAH in ~10% of patients.
Gross appearance of kidneys in ADPKD
- Grossly enlarged, multiple cysts containing blood, no recognizable kidney tissue
In what age group is ADPKD seen typically?
- ADults (mnemonic: AD)
In what age group is ARPKD seen typically?
- Childhood
Mutation(s) involved in ARPKD
- PKHD1 (PKHD = polycystic kidney and hepatic disease)
Gross appearance of kidneys in ARPKD
- Hugh, white, smooth-surfaced kidneys at birth with cysts 1-2 mm developing from collecting ducts
What else should ARPKD patients be checked for?
- Hepatic fibrosis that is congenital
Compare and contrast: focal vs diffuse and global vs segmental in terms of renal pathology
- Focal = 50% of glomeruli
- Global = whole glomerulus; segmental = portion of glomerulus
Immunoglobulins present and not present in glomerular disease
- GAM present
- Not ED. Mnemonic: don’t want your friends to get ED.
Pathogenesis of glomerular disease
- Antibodies against native GBM, antibodies against planted antigens, trapping of ag-ab complexes, antibodies against glomerular cells, cell mediated immunity
3 main clinical renal syndromes. Define where injury is and main clinical Ssx?
**
- Nephritic syndrome: breaks in glomerular capillary loops. Sx = hematuria, HTN, RBC casts. Renal failure can happen, in which case it is called acute nephritic syndrome.
- Nephrotic syndrome: defects in glomerular filtration, with podocyte processes effaced. Sx = severe proteinuria (> 3.5 g/24 hr), hypoalbuminemia (edema), fatty casts
- Acute renal failure: tubular injury. Sx = oliguria and rapid rise in serum Cr.
Gross and microscopic findings of chronic renal failure
- Note: results from untreated on unresponsive nephrotic syndrome/nephritic syndrome or acute renal failure
1. Gross: kidneys small, cortex thinned, increased pelvic fat
2. Micro: glomerular sclerosis, interstitial fibrosis, tubular atrophy
Causes of nephrotic syndrome
- Primary = minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, membranoproliferative glomerulonephritis (MPGN)
- Secondary = diabetic nephropathy, SLE, amyloidosis
- Other systemic disorders: DM, amyloidosis, SLE, drugs, infection, malignancies
What is the most common cause of nephrotic syndrome in children 2-6 yo?
- Minimal change dz (MCD aka minimal change glomerulopathy / lipoid nephrosis)
What is minimal change disease?
- Glomerular disease. One of causes of nephrotic syndrome and most common cause of this in children 2-6 yo.
Microscopic findings (LM, IF and EM) in MCD
- LM: normal, maybe lipid in tubular cells *different to FSGS
- IF: normal
- EM: diffuse epithelial foot process effacement *like FSGS
Tx of MCD
- Almost always responsive to steroids
What is focal segmental glomerulosclerosis (FSGS)? Causes? Describe morphologic course?
- What? Progressive glomerular scarring (fibrosis) disease that leads to nephrotic syndrome. Has some nephritic syndrome components (HTN often, microscopic hematuria).
- Causes: 80% idiopathic, other = virus associated (incl. HIV), drug associated (incl. HEROIN), genetic, hemodynamic adaptations
- Morphologic course: Early in disease, glomerulosclerosis = focal and segmental. Late in disease, becomes diffuse and global.
Microscopic findings (LM, IF and EM) in FSGS
- LM: segmental sclerosis (“hyalinosis”) if early stage *different to MCD
- IF: mild IgM and C3 or negative *different to MCD
- EM: diffuse epithelial cell injury (foot process effacement)* like MCD
Tx of FSGS
- Responds to steroids variable
What is membranous glomerulopathy (aka membranous nephropathy/glomerulonephritis)?
- Glomerular disease with deposition of Ag-Ab complexes that leads to nephrotic syndrome.
Microscopic findings (LM, IF and EM) in membranous glomerulopathy (aka membranous nephropathy/glomerulnephritis)?
- LM: thickened stiff capillary walls (SPIKES) on silver stain
- IF: GRANULAR IgG and C3 along glomerular BM
- EM: subepithelial deposits of ab/ag complex
What is membranoproliferative glomerulonephritis (MPGN)? Type 1 vs type 2? Cause? Tx?
- What: Slow progressive glomerular disease that leads to nephrotic syndrome with a nephritic component (hematuria). 50% progresses to CRF within 10 years.
- Type 1: subendothelial deposits present + mesangial hypercellularity (increase in number). Cause = idiopathic or 2ndary to chronic immune complex disorders (SLE, hep B/C, etc.)
- Type 2: intramembranous deposits present + mesangial hypercellularity (increase in number). Cause = 70% have C3 nephritic factor (C3NeF – an autoantibody which stabilizes C3 convertase) stopping enzymatic degradation of C3 and leading to persistent C3 activation. Therefore low serum C3 seen.
- Tx: No treatment effective (steroids and immunosuppressives).
Microscopic findings (LM, IF and EM) in MPGN type 1?
- LM: thickening of GBM (TRAM TRACKS) seen with silver stain
- IF: granular C3 (often with IgG) *only C3 in MPGN type 2
- EM: SUBENDOTHELIAL and mesangial deposits – between endothelial and GBM
Microscopic findings (LM, IF and EM) in MPGN type 2?
- LM: thickening of GBM (TRAM TRACKS) seen with silver stain
- IF: granular C3 only! *with IgG in MPGN type 1
- EM: INTRAMEMBRANOUS deposits within lamina densa of GBM
In what MPGN disease is low serum C3 seen?
- MPGN type 2
What is acute nephritic syndrome?
- Nephritic syndrome + renal failure
Pathological conditions / change seen in acute nephritic syndrome? Diseases seen with each change?
- Diffuse proliferative glomerulonephritis: acute post-strep GN
- Crescentic glomerulonephritis: Goodpasture’s dz, Lupus nephritis, ANCA-associated diseases
* These aren’t diseases per se, but describe pathological changes and are associated with specific disease.
What is acute post-infectious GN (pka acute post-strep GN). Cause? Who is affected? SSx? Lab findings? Tx? Microscopic findings on LM, IF and EM?
- What: This is an acute nephritic syndrome occurring 1-3 weeks following infection.
- Cause: infectious (strep, staph, pneumococcus etc.). Typically seen with strep.
- Affected: children
- SSx: Hematuria, azotemia, oliguria, HTN
- Lab findings: low C3, ASO (anti-streptolysin O abs) titer serially elevated
- Morpho findings
a. LM = diffuse proliferative GN (mesangial and endothelium) with NEUTROPHILS (acute)
b. IF: scattered (STARRY SKY) IgG, IgM and C3 along GBM AND IN MESANGIUM
c. EM: subepithelial HUMPS, which is IgG, IgM and C3 focally
What is crescenteric glomerulonephritis? Causes? What are the components of the crescents?
- What: Glomerular disease where glomerular crescents are formed leading to severe renal failure and death if untreated.
- Causes: type I, II or III – see subsequent flash cards for diseases associated with these
- Components: anti-GBM abs (eg. Anti-fibrinogen), immune complexes, anti-PMN abs, fibrin forms leading to proliferation of epithelial cells, influx of monocytes and macrophages.
Type I crescenteric glomerulonephritis causes. Lab findings? Tx?
- Goodpasture’s disease (aka anti-GBM disease): autoimmune dz with production of abs against collagen IV in BM of glomerulus, lungs etc. Results in vasculitis esp. in lungs and kidneys causing a pulmonary-renal syndrome.
- Labs: anti-GBM ab elevated
- Tx: high dose steroids, cytotoxic agents, plasmapheresis
Type II crescenteric glomerulonephritis causes. Lab findings? Tx?
- Lupus nephritis: SLE where kidney is affected by deposition of all immunoglobulin GAM + C3/4. Lab findings = anti-dsDNA ab etc.
- IgA nephropathy (aka Berger dz): asymptomatic isolated hematuria (sometimes with mild proteinuria). It is the most common type of primary GN worldwide. Affects children and non-AA young adults (commonly).
- Henoch-Schönlein purpura
Type III crescenteric glomerulonephritis cause
- ANCA-associated disease (eg. Wegener’s granulomatosis): group of vasculitis disorders esp. affecting small vessels and can cause pulmonary-renal syndrome. ANCA (anti-neutrophil cytoplasmic antibody).
IF findings for type I crescenteric GN
- Type I = Goodpasture’s disease
- IF findings: linear capillary loop IgG (CIGARETTE SMOKE): capillary loops in glomerulus are outlined by linear anti-GBM ab
IF findings for type II crescenteric GN
- Type II = Lupus nephritis, IgA nephropathy, Henoch-Schönlein purpura
- IF findings: granular deposits of immunoglobulin in mesangium or capillary loops (LUMP-BUMPY)
IF findings for type III crescenteric GN
- Type III = ANCA-associated disease (eg. Wegener’s granulomatosis)
- IF findings: absent or minimal
Microscopic findings (LM, IF, EM) in IgA nephropathy?
- LM: mesangial proliferation (> 3 per region)
- IF: mesangial IgA
- EM: mesangial deposits
What diseases causes asymptomatic isolated hematuria?
- IgA nephropathy
- Alport syndrome (hereditary)
- Thin GBM disease (hereditary)
What is the most common type of primary GN worldwide?
- IgA nephropathy
What is Alport syndrome? Which group is affected? SSx? Microscopic morphology seen?
- What: genetic defect (X-linked dominant with incomplete penetrance) of glomerular basement membrane d/t mutation in gene encoding alpha-4 chain of collagen type IV. **Don’t confuse with Goodpasture’s, which is autoimmune dz with abs against GBM, specifically type IV collagen.
- Group: affects males, females carriers (incomplete penetrance)
- SSx: SENSORINEURAL DEAFNESS, microscopic hematuria, progresses to renal failure (progression noted by proteinuria)
- Microscopy: GBM thickening, splitting and lamination (BASKET-WEAVE PATTERN)
Microscopic findings (LM, IF and EM) seen in thin-GBM disease
- LM: normal
- IF: negative
- EM: thin GBM
What is the only glomerular disease with deposition of all Igs?
- Lupus nephritis. Deposition of GAM w/C3 and 4
Pathology findings in amyloidosis glomerulonephropathies
- Congo red shows apple-green birefringence under polarized light
What is acute tubular necrosis (ANT)? Etiologies
- Destruction of renal tubular epithelium leading to loss of renal function.
- Two types:
1. Ischemia: shock
2. Nephrotoxic: drugs, heavy metals, organic solvents, radiocontrast dyes, myoglobin (rhabdo)
Microscopic findings in ANT
- Necrotic debris in tubules, dilated tubules with flattened epithelium
Drugs that can cause acute interstitial nephritis. SSx / presentation.
- Synthetic penicillins, rifampin, ibuprofen, thiazide diuretics.
- SSx: 2 weeks following use of these meds = fever, eosinophilia, rash and acute renal failure (oliguria + increased Cr)