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Flashcards in Intro into the Glomerulus Deck (22)
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1
Q

The job of the glomerulus is to?

A
  1. Allow ultra-filtrate into Bowman’s space (water, electrolytes, glucose and AA);
  2. Prevent proteins and RBC
2
Q

Pathology of glomerulus occur when ______ and ______ are present

A

proteinuria and hematuria

3
Q

What are the 3 components of the glomerular filtration barrier?

A
  1. Capillary endothelium
  2. BM
  3. Podocytes (epithelial cells)
4
Q

Describe the components of the glomerular filtration barrier.

A
  1. -Capillary endothelium is the 1st barrier to filtration: fenestrated, only allowing small molecules (~40nm) molecules to pass; does not allow RBCS, white cells or platelets
  2. -BM: negative charged molecules made up of proteins like type 4 collagen and heparin sulfate (- charged); repels (-) molecules, like albumin; only ~4nm can pass
  3. -Podocytes (epithelial cells): have foot processes that wrap around capillaries and form slits to filter PROTEINS
    • Largely responsible for making GBM
    • Injury => proteinuria
5
Q

Albumin is the major protein in the blood; small (~3.6nm) and can fit through all size barriers. Thus, what prevents filtration of it?

A

(-) charged BM

6
Q

Glomerular diseases are caused by___________________=> cause RBCS and protein (esp albumin) in urine, which should not be there.

A

Breakdown of the filtration barrier

7
Q

How can we measure blood in the urine?

A
  1. UA dipstick- tests for heme, which has peroxidase activity
  2. Microscopy
8
Q

Glomerular bleeding forms what?

A
  • red cell casts (bunch), dysmorphic RBCS, acanthocytes (spikey RBC), proteinuria,
  • clots are generally not seen
9
Q

How can we measure proteins in the urine?

A
  1. UA dipstick- tests for albumin, thus, tells us if we have a glomerular disease
  • Often 4+ if a glomerular disease
  • Affected by amount of urine
  1. Urine protein-to-creatinine level (spot urine test);
  • Take the 1st or 2nd morning urine sample test after avoid excercise;
  • NL ratio is less than 0.2 mg/mg);
  1. 24 hour urine collection
  • GOLD STANDARD, gives you grams/day or protein excretion;
  • NL is less than 150 mg/day
10
Q

Glomerular diseases occur on a spectrum. Describe the 3 findings in each nephritic syndromes and nephrotic syndromes.

A
  • Nephritic syndrome: Hematuria (RBC casts), azotremia, mild proteinuria and HTN
    • Proteinuria is less then 3.5g/day
  • Nephrotic syndrome: Severe proteinuria (hypoalbumenemia), hyperlipidemia and lipiduria
    • Proteinuria is more than 3.5g/day (less in children)
    • Hypoalbuminemia is plasma levels less than 3gm/dL
    • 4+ on dipstick
11
Q

Major determinant of whether a disease leads to nephritic or nephrotic syndrome is the what?

A

SITE of glomerular injury

12
Q

Damage to what part of the glomerulus leads to nephritic syndrome?

​Does inflammation occur?​

A
  • Endothelial/mesangial cells, with an influx of inflammatory cells that damage the entire glomeruli (nephritis) ==>
    • ​ Filtration barrier to RBC and proteins are lost.
13
Q

Damage to what part of the glomerulus causes nephrotic syndrome?

Does inflammation occur?

A
  • Podocytes (epithelial cells) ONLY=> protein loss only
    • Filtration barrier to RBC: intract
    • Podocytes are separated from the blood by the GBM.
    • Thus, injury does not lead to inflammation.
14
Q

Nephritic syndrome is often an __________ process that damages the __________, thus, damaging the filtration barrier ______________.

  • _______ onset dominated by acute onset of grossly visible __________, _______, ________.
A
  • Inflammatory
  • Entire glomerulus
  • To RBC and proteins
  • Acute
  • Hematuria, mild proteinuria and HTN
15
Q

Describe the processes that occur in the body when a patient has nephritic syndrome

A
  • Damage to the entire filtratration barrier causes: hematuria (dysmorphic RBCs/RBC clasts) and mild proteinuria (less than 3.5 g/day).
    • ↓ GFR =>
      • Azotremia (↑ in BUN/Cr)
      • Oliguria
      • ↑ hydrostatic pressure causes HTN and edema
16
Q

Describe the processes that occur in the body when a patient has nephrotic syndrome

A
  • Damage to protein filtration barrier causes:
    1. Frothy urine d/t ↑ proteins in the urine (>3.5 g/day)
    2. ↓ in albumin
      • ↑ liver activity to make more => hyperlipidemia & and fatty casts/oval bodies in urine (lipiduria)
      • Severe edema occurs via 2 mechanisms:
        • plasma oncotic pressure
        • ↓ ECV and GFR => + RAAS => Na/H20 retention => worsening edema
    3. ↓ of immunoglobulins => more prone to infection
    4. ↓ in antithrombin 3 => pt is in hypercoagulable state
17
Q

What is the classic presentation of a patient with nephritic syndrome?

A
  1. Dark urine (RBCs)
  2. Swelling and fatigue (d/t uremia)
  3. <3.5g/day proteinuria
18
Q

What is the classic presentation of a patient with nephrotic syndrome?

A
  • Frothy urine d/t proteinuria (>3.5 grams/day)
  • Swelling of ankles/around eyes (periorbital edema), often mistaken for an allergic reaction
  • Serum total cholesteral (>300mg/dl; mainly LDL)
19
Q

In nephrotic syndrome, lipids are present in the urine.

What is unique about them?

A
  • Organized in fatty casts and can be enclosed by plasma membrane of degenerative epithelial cells (oval fat bodies)
  • Under polarized light, fat droplets look like a maltese cross.
20
Q

How can we DX nephrotic vs. nephritic syndromes?

A
  1. Light microscopy
  2. Immunofluorescence
  3. Electron microscopy: used to look at BM, podocytes
21
Q

What are the major causes of nephritic syndrome?

A
  1. Post-streptococcal diffuse proliferative glomerulonephritis
  2. Berger’s IgA nephropathy
  3. Diffuse (acute) proliferative glomerulonephritis
  4. RPGN
  5. Alport Syndrome
  6. Membranoproliferative glomerulonephritis
22
Q

What are the major causes of nephrotic syndrome?

A
  1. Minimal change disease: d/t cytokines
  2. Focal segmental glomerulosclerosis (FSGS): d/t podocyte damage
  3. Membranous nephropathy: d/t immune complexes
  4. Diabetic: glucose
  5. Amyloidosis
  6. Membranoproliferative glomerulonephritis