Renal Flashcards Preview

USMLE Step 1: Things I Cannot Remember > Renal > Flashcards

Flashcards in Renal Deck (58):
1

POTTER sequence syndrome

  1. Pulmonary hypoplasia
  2. Oligohydramnios
  3. Twisted face
  4. Twisted skin
  5. Extremity defects
  6. Renal failure (in utero)

2

  • Plasma volume is measured by ....
  • Extracellular volume measured by .... 
  • Osmolality = .... mOsm/kg H2O
  • GFR can be best estimated with ....
  • RPF is best estimated with .... 

  • Plasma volume is measured by radiolabeled albumin
  • Extracellular volume measured by inulin 
  • Osmolality = 285-295 mOsm/kg H2O
  • GFR can be best estimated with creatinine clearance
  • RPF is best estimated with PAH clearance 

3

  1. Filtered load = 
  2. Excretion rate = 
  3. Reabsorption = 
  4. Secretion = 

  1. Filtered load = GFR x Px
  2. Excretion rate = V x Ux 
  3. Reabsorption = filtered – excreted
  4. Secretion = excreted – filtered

4

  • Afferent arteriole constriction 
  • Efferent arteriole constriction
  • ↑ plasma protein concentration
  • ↓ plasma protein concentration
  • Constriction of ureter

  • Afferent arteriole constriction
    • ↓ GFR, ↓ RPF, – FF
  • Efferent arteriole constriction
    • ↑ GFR, ↓ RPF, ↑ FF
  • ↑ plasma protein concentration
    • ↓ GFR, – RPF, ↓ FF
  • ↓ plasma protein concentration
    • ↑ GFR, – RPF, ↑ FF
  • Constriction of ureter
    • ↓ GFR, – RPF, ↓ FF

5

  • Where are amino acids reabsorbed? 
  • What is Hartnup's disease?

 

  • Amino acid clearance:
    • Na+-dependent transporter in PCT reabsorb amino acids
  • Hartnup's disease
    • Autosomal recessive
    • Deficiency of neutral amino acids (e.g. tryptophan) transporter in proximal renal tubular cells and on enterocytes ⇒
      • neutral aminoaciduria and ↓ absorption from gut
    • ↓ tryptophan for conversion to niacin ⇒ pellagra-like symptoms
    • Treatment: high protein diet + nicotinic acid

6

Glucose clearance: 

  • Site of absorption: 
  • Threshold: 
  • What happens in pregnancy?

  • Site of absorption: 
    • At normal levels, completely reabsorbed in PCT by Na+/glucose co-transport
  • Threshold: 
    • ~200 mg/dL ⇒ glucosuria begins
    • ~375 mg/dL ⇒ all transporters are fully saturated (Tm)
  • What happens in pregnancy?
    • normal pregnancy may decrease the ability of PCT to reabsorb glucose and amino acids ⇒
      • glucosuria and aminoaciduria

7

Where do PTH and AT II act?

  • PTH (early PCT) → inhibits Na+/PO43- cotransport → PO43- excretion
  • PTH (early DCT) → ↑ Ca2+/Na+ exchange → Ca2+ reabsorption
  • AT II (early PCT) → stimulates Na+/H+ exchange → ↑ Na, H2O and HCO3– reabsorption (permitting contraction alkalosis) 

8

When does urine become hypertonic?

Thin descending loop of Henle

  • passively reabsorbs H2O via medullary hypertonicity (impermeable to Na+)

9

When does urine become the most dilute (hypotonic)?

Early DCT

10

Where do aldosterone and ADH act?

Collecting tubule

  • Aldosterone (acts on mineralocorticoid receptor) → mRNA → protein synthesis
    • In principal cells: ↑ apical K+ conductance, ↑ Na+/K+ pump, ↑ ENaC channels → lumen negativity → K+ loss
    • In α-intercalated cells: ↑ H+ ATPase activity → ↑ HCO3-/Cl- exchanger activity
  • ADH (acts on V2 receptor) → insertion of aquaporin H2O channels on apical side

11

List the renal tubular defects

"The kidneys put out FABulous Glittering LiquidS"

  1. FAnconi syndrome (affects PCT)
  2. Bartter syndrome (affects thick ascending loop)
  3. Gitelman syndrome (affects DCT)
  4. Liddle syndrome (affects collecting tubule)
  5. Syndrome of apparent mineralcorticoid excess 

12

Fanconi syndrome:

  • Area affected: 
  • Associations: 
  • Causes: 

  • Area affected: 
    • reasorptive defect of PCT
  • Associations: 
    • ↑ excretion of nearly all amino acids, glucose, HCO3- and PO43-
    • May result in proximal renal tubular acidosis (metabolic acidosis w/ normal anion gap)
  • Causes: 
    • hereditary defects (Wilson disease, tyrosinemia, glycogen storage disease)
    • ischemia
    • multiple myeloma
    • nephrotoxins/drugs (expired tetracyclines, tenofovir)
    • Pb poisoning

13

Bartter syndrome 

  • Area affected:
  • Mode of inheritance:
  • Results in ....

  • Area affected: 
    • reabsoprtive defect in thick ascending loop of Henle
    • Na+/K+/2Cl- cotransporter
  • Mode of inheritance:
    • autosomal recessive
  • Results in hypokalemia and metabolic alkalosis w/ hypercalciuria

14

Gitelman syndrome

  • Area affected:
  • Mode of inheritance:
  • Results in ....

  • Area affected: 
    • reabsorptive defect of NaCl in DCT
  • Mode of inheritance:
    • autosomal recessive
    • less severe than Bartter syndrome
  • Results in hypokalemia, hypomagnesemia, metabolic alkalosis, hypocalciuria

15

Liddle syndrome

  • Area affected:
  • Mode of inheritance:
  • Results in ....
  • Treatment ⇒ 

  • Area affected: 
    • Gain of function mutation → ↑ Na+ reabsorption in collecting tubules (↑ activity of ENaC)
  • Mode of inheritance: 
    • autosomal dominant
  • Results in HTN, hypokalemia, metabolic alkalosis, ↓ alsosterone
  • Treatment ⇒ Amiloride 

16

Syndrome of apparent mineralocorticoid excess

  • How is it acquired? 
  • Pathophysiology: 
  • What will be seen on labs?
  • Results in ....

  • How is it acquired? 
    • Hereditary deficiency of 11β-hydroxysteroid dehydrogenase (converts cortisol ⇒ cortisone)
    • Can be acquired from glycyrrhetic acid (present in licorice) which blocks 11β-hydroxysteroid dehydrogenase activity
  • Pathophysiology: 
    • Excess cortisol → ↑ mineralocorticoid receptor activity 
  • Labs show low serum aldosterone levels
  • Results in HTN, hypokalemia, metabolic alkalosis

17

K+ shifts 

  • Causes of Hyperkalemia
  • Causes of Hypokalemia

  • Causes of Hyperkalemia ("DO LAβS")
    • Digitalis (blocks Na+/K+ ATPase)
    • HyperOsmolarity
    • Lysis of cells (crush injury, rhabdomyolysis, cancer)
    • β-blockers
    • High blood Sugar
  • Causes of Hypokalemia
    • Hypo-osmolarity
    • Alkalosis
    • β-agonists (↑ Na+/K+ ATPase)
    • Insulin (↑ Na+/K+ ATPase)
      • Insulin shifts K+ into cells

18

Electrolyte disturbances: Low serum concentrations

  • Na+
  • K+
  • Ca2+
  • Mg2+
  • PO43-

  • Na+ 
    • Nausea, malaise, stupor, coma, seizures
  • K+ 
    • U waves on EKG, flattened T waves, arrhythmias, muscle spasms
  • Ca2+ 
    • Tetany, seizures, QT prolongation
  • Mg2+ 
    • Tetany, torsades de pointes, hypokalemia
  • PO43- 
    • Bone loss, osteomalacia (adults), rickets (children)

19

Electrolyte disturbances: High serum concentrations

  • Na+ 
  • K+ 
  • Ca2+ 
  • Mg2+ 
  • PO43- 

  • Na+ 
    • irritability, stupor, coma
  • K+ 
    • wide QRS and peaked T waves on EKG, arrythmias, muscle weakness
  • Ca2+ 
    • "Stones (renal), Bones (pain), Groans (abdominal pain), Thrones (↑ urinary frequency) and Psychiatric Overtones (anxiety, AMS)"
  • Mg2+ 
    • ↓ DTRs, lethargy, bradycardia, hypotension, cardiac arrest, hypocalcemia
  • PO43- 
    • renal stones, metastatic calcifications, hypocalcemia

20

Features of Nepritic Syndrome:

due to GBM disruption

  • HTN
  • ↑ BUN and creatinine
  • azotemia
  • oliguria
  • hematuria
  • RBC casts
  • proteinuria < 3.5 g/day

21

Features of Nephrotic Syndrome:

due to podocyte disruption → charge barrier impaired

  • massive proteinuria (> 3.5 g/day) w/ hypoalbuminemia
  • hyperlipidemia → fatty casts
  • edema

Associated with hypercoagulable state (loss of AT III in urine) and ↑ risk of infection (loss of Ig in urine)

22

List the nephritic syndromes:

  1. Acute poststreptococcal glomerulonephritis
  2. Rapidly progressive glomerulonephritis
  3. IgA nephropathy (Berger disease)
  4. Alport syndrome
  5. Membranoproliferative glomerulonephritis

23

List the nephrotic syndromes:

  1. Focal segmental glomerulosclerosis
  2. Minimal change disease
  3. Membranous nephropathy
  4. Amyloidosis
  5. Diabetic glomerulonephropathy

24

List the nephritic-nephrotic syndromes:

  1. Diffuse proliferative glomerulonephritis
  2. Membranoproliferative glomerulonephritis

25

Which nephritic syndrome is most commonly seen in children?

acute poststreptococcal glomerulonephritis

26

What is the most common cause of death in SLE?

diffuse proliferative glomerulonephritis

27

Henoch-Schölein purpura = ....

Henoch-Schölein purpura = IgA nephropathy

28

Acute Poststreptococcal Glomerulonephritis

  • Pathology
    • LM
    • EM
    • IF
  • Clinical Features
    • Epidemiology
    • Symptoms
    • Labs
    • Treatment

  • Pathology
    • LM: glomeruli enlarged and hypercellular
    • EM: subepithelial immune complex humps
    • IF: (starry sky) granular appearance (lump bumpy)
  • Clinical Features
    • Epidemiology: in children ~2 weeks after group A strep infection of skin or pharynx; Type 3 hypersensitivity
    • Symptoms: peripheral and periorbital edema; cola-colored urine
    • Labs: ↑ anti-DNase B titers; ↓ complement levels
    • Treatment: self-limited

29

Rapidly Progressive (crescentic) Glomerulonephritis

  • Pathology
    • LM & IF:
  • Associated disease processes
  • Clinical Features
    • Symptoms
    • Treatment

  • Pathology
    • LM & IF: crescent moon shape
      • consists of fibrin and plasma proteins with glomerular parietal cells, monocytes/macrophages
  • Associated disease processes
    • Goodpasture syndrome – type 2 hypersensitivity
      • Ab to GBM and alveolar basement membrane → linear IF
    •  Granulomatosis w/ polyangitis (Wegener's)
      • PR3-ANCA/c-ANCA
    • Microscopic polyangitis
      • MPO-ANCA/p-ANCA
  • Clinical Features
    • Symptoms: Hematuria/hemoptysis
    • Treatment: emergent plasmapheresis; poor prognosis

30

Diffuse Membranoproliferative Glomerulonephritis

  • Causes
  • Pathology 
    • LM
    • EM
    • IF
  • Clinical associations

  • Causes: 
    • 2/2 to SLE or membranoproliferative glomerulonephritis
  • Pathology 
    • LM: "wire-looping" of capillaries ("wire-lupus")
    • EM: subendothelial (sometimes intramembranous) IgG-based ICs often with C3 deposition
    • IF: granular
  • Clinical associations:
    • most common cause of death in SLE
    • often presents as nephrotic and nephritic syndrome concurrently

31

IgA nephropathy

  • Pathology
    • LM:
    • EM:
    • IF:
  • Associated with ....
  • Clinical features

  • Pathology
    • LM: mesangial proliferation
    • EM: mesangial IC deposits
    • IF: IgA-based IC deposits in mesangium
  • Renal pathology of Henoch-Schölein purpura
  • Clinical features:
    • often presents with renal insufficiency or acute gastroenteritis
    • episodic hematuria w/ RBC casts

32

  • What is the mutation in Alports syndrome? 
  • How is Alport syndrome inherited? 
  • What are the clinical signs/symptoms of Alport syndrome?
  • What is the appearance on EM?

  • What is the mutation in Alports syndrome? 
    • mutation in type IV collagen → thinning and splitting of GBM
  • How is Alport syndrome inherited? 
    • X-linked
  • What are the clinical signs/symptoms of Alport syndrome? ("Can't see, can't pee, can't hear a buzzing bee")
    • Eye problems, glomerulonephritis, sensorineural deafness
  • What is the appearance on EM?
    • "basket-weave" appearance 

33

Membrano-proliferative glomerulonephritis: Type I vs. Type II

  1. Type I
    • Pathology
    • Associations
  2. Type 2
    • Pathology
    • Associations 

  1. Type I
    • Pathology: 
      • subendothelial IC deposits w/ granular IF
      • "tram-track" appearance on PAS stain and H&E stain (GBM splitting caused by mesangial ingrowth)
    • Associations:
      • idiopathic; often 2/2 Hep B or Hep C infection
  2. Type 2
    • Pathology: 
      • intramembranous IC deposits; "dense deposits"
    • Associations:
      • C3 nephritic factor (stabilizes C3 convertase → ↓ serum C3 levels) 
  • MPGN often copresents as a nephritic and nephrotic syndrome

34

What is the most common cause of nephrotic syndrome in African Americans and Hispanics?

focal segmental glomerulosclerosis

35

What is the most common cause of nephrotic syndrome in children?

minimal change disease

36

What is the nephrotic presentation of SLE?

membranous nephropathy

37

What is the most common cause of nephrotic syndrome in Caucasians?

membranous nephropathy

38

Apple-green birefringerence under polarized light → 

amyloidosis

39

Kimmelstiel-Wilson lesions → 

diabetic glomerulonephropathy

40

Response to steroids:

  • Focal segmental glomerulosclerosis ⇒
  • Minimal change disease (lipoid nephrosis) ⇒
  • Membranous nephropathy ⇒ 

Response to steroids:

  • Focal segmental glomerulosclerosis 
    • inconsistent response
  • Minimal change disease (lipoid nephrosis)
    • excellent response
  • Membranous nephropathy
    • poor response 

41

Focal segmental glomerulosclerosis

  • Pathology
    • LM
    • EM
    • IF
  • Clinical associations

  • Pathology
    • LM: segmental sclerosis and hyalinosis
    • EM: effacement of foot process
    • IF: nonspecific for focal deposits of IgM, C3, C1
  • Clinical associations
    • ​African Americans and Hispanics
    • Idiopathic
    • HIV infection
    • Sickle cell disease
    • heroin abuse
    • interferon treatment
    • CKD due to congenital malformation

42

Minimal change disease (lipoid nephrosis)

  • Pathology 
    • LM:
    • EM:
    • IF
  • Clinical associations

  • Pathology 
    • LM: normal glomeruli
    • EM: effacement (fusion) of foot processes
    • IF: ()
  • Clinical associations
    • children
    • idiopathic
    • recent infection
    • immunization
    • immune stimulus

43

Membranous nephropathy

  • Pathology
    • LM: 
    • EM: 
    • IF: 
  • Clinical associations

  • Pathology
    • LM: diffuse capillary and GBM thickening
    • EM: granular (IC deposition)
    • IF: "spike-dome" appearance w/ epithelial deposits
  • Clinical associations
    • idiopathic
    • SLE
    • Ab to phospholipid A2 receptor
    • drugs – NSAIDs, penicillamine
    • infections – HBV, HCV
    • solid tumors

44

  • What is the most commonly involved organ in amyloidosis?
  • What conditions is amyloidosis associated with?

  • kidney are the most commonly involved organ 
  • Amyloidosis is associated with chronic conditions
    • mulitple myeloma
    • TB
    • RA

45

Diabetic glomerulonephropathy

  • Pathology
  • Pathophysiology

  • Pathology
    • LM: mesangial expansion, GBM thickening, eosinophilic nodular glomerulosclerosis
  • Pathophysiology
    • Nonenzymatic glycosylation of GBM → ↑ permeability; thickening
    • Nonenzymatic glycosylation of efferent arterioles → ↑ GFR → mesangial expansion

46

Casts in urine

  1. RBC casts
  2. WBC casts
  3. Fatty casts ("oval fat bodies")
  4. Granular ("muddy brown") casts
  5. Waxy casts
  6. Hyaline casts

  1. RBC casts
    • glomerulonephritis, malignant HTN
  2. WBC casts
    • tubulointerstitial inflammation, acute pyelonephritis, transplant rejection
  3. Fatty casts ("oval fat bodies")
    • nephrotic syndrome
  4. Granular ("muddy brown") casts
    • acute tubular necrosis
  5. Waxy casts
    • ESRD/chronic renal failure
  6. Hyaline casts
    • nonspecific, can be normal; often seen in concentrated urine samples

47

  • hematuria, no casts ⇒ 
  • pyuria, no casts ⇒ 

  • hematuria, no casts ⇒ bladder cancer, kidney stones
  • pyuria, no casts ⇒ acute cystitis

48

Causes of respiratory acidosis

respiratory acidosis ⇒ hypoventilation

  1. airway obstruction
  2. acute lung disease
  3. chronic lung disease
  4. opioids/sedatives
  5. weakening of respiratory muscles

49

Causes of anion gap metabolic acidosis w/ compensation (hyperventilation)

anion gap metabolic acidosis

  1. Methanol (formic acid)
  2. Uremia
  3. Diabetic ketoacidosis
  4. Propylene glycol
  5. Iron tablets/Isoniazid
  6. Lactic acidosis
  7. Ethylene glycol (oxalic acid)
  8. Salicylates (late presentation)

50

Causes of non-anion gap metabolic acidosis w/ compensation (hyperventilation)

non-anion gap metabolic acidosis

  1. Hyperalimentation
  2. Addison disease
  3. Renal tubular acidosis
  4. Diarrhea
  5. Acetazolamide
  6. Spironolactone
  7. Saline infusion

51

Causes of respiratory alkalosis

respiratory alkalosis → hyperventilation

  1. hysteria
  2. hypoxemia (e.g. high altitude)
  3. salicylates (early presentation)
  4. tumor
  5. pulmonary embolism

52

Causes of metabolic alkalosis w/ compensation (hypoventilation)

metabolic alkalosis

  1. loop/thiazide diuretics
  2. vomitting
  3. antacid use
  4. hyperalodosteronism

53

  1. What is the most common primary renal malignancy? 
  2. What is the genetic association? 
  3. What are other clinical associations?
  4. How does it metastisize?

  1. renal cell carcinoma (RCC)
  2. Associated w/ gene deletion on chromosome 3 
    • sporadic or inherited as von Hippel-Lindau syndrome
  3. Also associated w/ paraneoplastic syndromes (ectopic EPO, ACTH, PTHrP)
  4. Metastasis: hematogenously
    • renal vein ⇒ IVC ⇒ lung and bone

54

Renal oncocytoma

  • Definition: 
  • Pathologic findings:
  • Clinical presentation:

  • Definition: 
    • benign epithelial cell tumor
  • Pathologic findings: 
    • large eosinophilic cells w/ abundant mitochondria w/o perinuclear clearing
  • Clinical presentation: 
    • painless hematuria, flank pain, abdominal mass

55

What is the most common renal malignancy of early childhood?

  • Clinical presentation: 
  • Mutations: 
  • Clinical associations: 

most common renal malignancy of early childhood ⇒ Wilm's tumor

  • Clinical presentation: 
    • large, palpable unilateral flank mass +/- hematuria
  • Mutations: 
    • "loss of function" mutations of tumor suppresion genes WT1 or WT2 on chromosome 11
  • Clinical associations: 
    • Beckwith-Wiedmann syndrome
      • Wilm's tumor, macroglossia, organomegaly, hemihypertrophy
    • WAGR complex
      • Wilm's tumor, Aniridia, Genitourinary malformation, mental Retardation

56

  • Most common malignancy of urinary tract ⇒ 
  • Associated with problems in your Pee SAC

  • Most common malignancy of urinary tract ⇒ transitional cell carcinoma
  • Associated with problems in your Pee SAC
    • Phenacetin
    • Smoking
    • Aniline dyes
    • Cyclophosphamide

57

What are the risk factors for SCC of the bladder?

Risk factors for SCC of the bladder

  1. Schistosoma haematobium infection (Middle East)
  2. chronic cystitis
  3. smoking
  4. chronic nephrolithiasis

Chronic irritation of urinary bladder → squamous metaplasia → dysplasia → SCC

58