Proteinuria Flashcards

1
Q

How does a normal kidney handle albumin?

A
  • approximately 4 g/dL albumin is present in plasma
  • 2-3 mg/dL is normally filtered by the glomerulus, but is largely reabsorbed by the proximal tubule
  • <1 mg/dL albumin is present in the normal urine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is proteinuria?

A

presence of any type of protein in the urine - albumin, globulins, mucoproteins, Bence-Jones proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are 3 causes of physiologic proteinuria?

A
  1. exercise
  2. stress
  3. fever
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are signs of non-urinary pathologies that cause proteinuria?

A
  • Bence-Jones proteins (multiple myeloma)
  • myoglobinuria
  • hemoglobinuria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 2 classifications of urinary pathologies that cause proteinuria?

A
  1. RENAL - glomerular, tubular, parenchymal inflammation
  2. NONRENAL - lower urinary tract inflammation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What determines persistent proteinuria?

A

minimum 3 urine samples with protein 2 or more weeks apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What causes renal proteinuria? 3 examples?

A

structural or functional lesions within the kidneys

  1. GLOMERULAR - altered selectivity properties of the glomerular capillary wall
  2. TUBULAR - impaired tubular recovery of plasma proteins
  3. INTERSTITIAL - inflammatory lesions or disease processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is indicative of tubular proteinuria? What are 4 causes?

A

UPC 0.5-1.0, sometimes accompanied by normoglycemic glucosuria and excessive urinary loss of electrolytes

  1. tubular disease
  2. renal tubular acidosis causes damage
  3. renal glucosuria
  4. Fanconi’s acquired from chicken jerky treats from China
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is indicative of glomerular proteinuria?

A

persistent UPC > 1.0 with inactive sediment (possibly some hyaline)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are 7 causes of glomerular disease that can lead to proteinuria in dogs?

A
  1. amyloidosis
  2. glomerulosclerosis
  3. glomerulonephritis (immune, infectious)
  4. hereditary nephritis
  5. lupus nephritis
  6. membranous nephropathy
  7. idiopathic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In what dogs is glomerular amyloidosis common? Hereditary?

A

Beagle, Collie, English Foxhound, Walker hound

Shar Pei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In what cats is glomerular amyloidosis hereditary?

A
  • Abyssinian
  • Siamese
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Diseases reported in association with glomerular diseases in dogs:

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Diseases reported in association with glomerular diseases in cats:

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is proteinuria commonly monitored?

A
  • poor prognostic indicator with CKD and Lyme
  • helps assess severity of disease and response to treatment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does the magnitude of azotemia compare to level of response to proteinuria in dogs?

A

AZOTEMIC DOGS - intervene with a UPC > 0.5

NONAZOTEMIC DOGS - intervene with a UPC > 2.0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does the magnitude of azotemia compare to level of response to proteinuria in cats?

A

AZOTEMIC CATS - intervene with a UPC > 0.4

NONAZOTEMIC CATS - intervene with a UPC > 2.0

18
Q

How is proteinuria diagnosed?

A

UA - needs to be persistent and lack active urine sediment (pyuria, gross hematuria)

  • dipstick
  • SSA
  • microalbumin
  • UPC
19
Q

What is the dipstick? What limitations does it have? When are false positives seen?

A

colorimetric screening test that measures albumin in the urine, usually confirmed with UPC or SSA

lower limit of protein detection - 30 mg/dL

alkaline urine, common in cats

20
Q

What is SSA? What is it used for? What limitation does it have?

A

sulfosalicylic acid turbidimetric test on a scale of 0-4+

delineates between a true and false positive dipstick test, confirmed further with a UPC

lower limit of protein detection - 5 mg/dL

21
Q

When are microalbuminuria tests recommended?

A

when albumin in the urine is greater than normal (> 1.0 mg/dL), but below the limit of detection using conventional dipstick (< 30 mg/dL)

  • early increases in albuminuria may indicate glomerular damage undetectable by other methods
22
Q

What is the gold standard test for proteinuria? What are the 2 techniques used?

A

urine protein:creatinine (UPC)

  1. measuring a UPC of a single urine sample
  2. averaging UPCs from 3 consecutive daily urine samples
23
Q

What work up is recommended in cases of proteinuria?

A
  • CBC/chem
  • UA
  • urine culture
  • UPC
  • blood pressure
  • AUS
  • infectious disease testing
24
Q

What is required to make a definitive of causes of proteinuria?

A

renal biopsies —> can identify amyloid and immune-mediated disease

  • rarely done in practice; will not change plan but does provide prognostic information
25
Q

What renal disease that causes proteinuria has a particularly poor prognosis?

A

amyloidosis - no treatment

26
Q

What are 5 consequences of proteinuria?

A
  1. hypoalbuminemia
  2. edema/ascites - decreased oncotic pressure
  3. hypercholesterolemia - body response to poor oncotic pressure
  4. systemic hypertension
  5. hypercoagulability - decreased antithrombin
27
Q

How does proteinuria affect the nephrons?

A

causes glomerular and tubulointerstitial damage and results in progressive nephron loss

  • protein accumulation in Bowman’s capsule
  • mesangial cell proliferation
  • glomerulosclerosis
  • nephron loss
  • decreased autoregulation
28
Q

What are the 4 steps to treatment of proteinuria? What are the benefits of this treatment?

A
  1. diet - decreased protein
  2. ARBs, ACE-i
  3. antiplatelet therapy - Clopidogrel
  4. omega 3 PUFA

reduces progression of disease and azotemia

29
Q

How does the renin-angiotensin-aldosterone system work? How do antihypertensives work on this system?

A
  • liver produces angiotensinogen
  • kidney produced renin, which cleaves angiotensinogen into angiotensin I
  • ACE from the lungs cleaves ANGI into ANGII, which constricts blood vessel smooth muscle
  • ANGII acts on the adrenal gland to release aldosterone, which stimulates reabsorption of sodium and water

TELMISARTAN blocks ACE receptors and ENALAPRIL/BENZALAPRIL blocks ACE directly, blocking ANGII production

30
Q

How do ACE-i and ARBs affect the kidneys?

A

decreases efferent resistance, which increases RBF and decreases GFR

31
Q

Mechanisms and adverse effects of antihypertensives:

A
32
Q

How is therapeutic response to proteinuria treatment assessed? What is the goal of therapy?

A

urine is collected over several days by the owner and pooled, and collected at visit for a UPC

> 90% reduction in cats, >50% reduction in dogs —> reduction below 0.5 (normal) is not commonly possible

33
Q

What are 2 complications associated with proteinuria therapy?

A
  1. decreased GFR from ACE-i and ARBs can worsen azotemia
  2. hyperkalemia - decreased aldosterone causes a decrease in sodium and potassium reabsorption
34
Q

When are we concerned about potassium levels in proteinuria treatment?

A

> 6.5 mEq/L has cardiac effects

  • prolonged QRS complex and PR interval
  • depressed R wave amplitude
  • decreased ST segment
35
Q

What should be done after starting anti-proteinurics?

A

7 day recheck of kidney values and electrolytes

  • look for worsening of azotemia (reduce ACE-i or ARB dose)
  • check potassium levels (< 6.5 mEq/L is safe)
36
Q

Other than antiproteinurics, what aspects of treatment should be done?

A
  • fluid therapy or diuretics
  • antithrombotics
  • antibiotics
  • omega 3 PUFA
  • immunosuppressives
37
Q

What role do omega 3 PUFAs have in treating proteinuria?

A

reduce proteinuria by reducing inflammation and vasoconstriction at the glomerulus

  • especially helpful with PLN
38
Q

What are the 2 major types of fluids used for fluid therapy in response to proteinuria? Why must this be done carefully?

A
  1. colloids - increases oncotic pressure
  2. crystalloids - low in sodium to avoid over-retention

proteinuric patients tend to be edematous AND dehydrated and fluid therapy can make edema worse —> cautiously give some fluids and if clinical signs worsen, stop and give loop diuretics

39
Q

Why is antiplatelet therapy commonly recommended in patients with proteinuria? What drugs are recommended?

A

thrombosis and thromboembolism is common due to antithrombin III loss from kidneys, making patients hypercoagulable

  • Clopidogrel (prevents plately activation)
  • low-dose Aspirin

(can cause GI upset and blood loss)

40
Q

When are antibiotics recommended for patients with proteinuria?

A
  • Lyme nephritis: Doxycycline (immune complex may require immunosuppression)
  • pyelonephritis: based on c/s

(NOT STANDARD - based on degree of suspicion)

41
Q

What 3 immunosuppressives are recommended for patients with proteinuria? What adverse effect is seen?

A
  1. Prednisone*
  2. Mycophenolate
  3. Cyclosporine
    (Ab-Ag complexes damage glomerulus)

leads to water retention —> Prednisone is commonly started while waiting for other immunosuppressives to work, then tapered off