Proteinuria + nephrotic syndrome Flashcards

1
Q

What is normal urine protein?

A

<150mg/day (usually 40-80mg/day)

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2
Q

What proteins are present in urine?

A

albumin
low molecular weight proteins - beta2 microglobulin, polypeptides, RBP
secreted proteins

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3
Q

How does proteinuria present?

A

asymptomatic and incidental detection on urine dipstick

heavy proteinuria = peripheral oedema, frothy urine

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4
Q

Advantages of urine dipstick

A

simple bedside test
rapid diagnosis
inexpensive

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5
Q

Disadvantages of urine dipstick

A

operator dependent
semi-quantitative
insensitive to low level proteinuria
does not detect non-albumin proteinuria

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6
Q

What tests other than dipstick can be used to detect proteinuria?

A

urine protein creatinine ratio
urine albumin creatinine ratio
24hr urine protein collection

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7
Q

Causes of benign proteinuria

A

orthostatic proteinuria - children and adolescents, <3.5g/day

transient proteinuria secondary to fever, heavy exercise, vasopressor, IV albumin, usually <1g/day

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8
Q

What is pathological glomerular proteinuria?

A

disruption to filtration barrier
can be associated with microscopic haematuria

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9
Q

Primary glomerulonephritides

A

minimal change disease

primary focal segmental

glomerulosclerosis

idiopathic membranous nephropathy

IgA nephropathy

Idiopathic membranoproliferative glomerulonephritis (MPGN)

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10
Q

Secondary glomerulonephritides

A

diabetes mellitus

systemic amyloidosis

secondary focal segmental glomerulosclerosis (eg. obesity, hypertension, HIV infection)

autoimmune disease (eg. SLE)

secondary membranous nephropathy (eg. cancer, drugs)

MPGN - hepatitis B or C

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11
Q

4 mechanisms of proteinuria

A

glomerular
tubular
overflow
post-renal

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12
Q

What is tubular proteinuria?

A

low molecular weight proteins are filtered at the glomerulus and reabsorbed by proximal tubules

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13
Q

Causes of tubular proteinuria

A

tubulo-interstitial nephritis

drugs eg. antibiotics, NSAIDs, PPIs

autoimmune disease eg. Crohn’s, sarcoidosis, Sjogren’s

infections eg. TB, CMV infection, leptospirosis

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14
Q

What is overflow proteinuria?

A

excess production of low molecular weight proteins exceed reabsorptive capacity of tubules

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15
Q

Causes of overflow proteinuria

A

myeloma (free light chains)
rhabdomyolysis (myoglobin)
haemolysis (haemoglobin)

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16
Q

What is post-renal proteinuria?

A

inflammation of lower urinary tract

17
Q

Causes of post-renal proteinuria

A

lower urinary tract infection
stones

18
Q

What is the clinical significance of proteinuria?

A

proteinuria is a risk factor for cardiovascular disease
proteinuria is a risk factor for progressive chronic kidney disease

19
Q

Assessment of a patient with proteinuria

A

history
examination
urine dipstick + quantification of proteinuria
assessment of renal function - serum creatinine + GFR
renal imaging - ultrasound
bloods - ANA, ANCA, anti-GBM, serum protein electrophoresis, serum free light chain ratio, hep B/C serology, complement, anti-PLA2R
renal biopsy

20
Q

What is nephrotic syndrome?

A

urine protein excretion >3.5g/day
hypoalbuminaemia (serum albumin <3g/dL)
oedema
hyperlipidaemia

21
Q

Clinical significance of nephrotic syndrome

A

untreated has high mortality:
- infection
- thrombosis
- established renal failure

22
Q

Renal pathophysiology in nephrotic syndrome

A

disruption of glomerular filtration barrier with podocyte effacement

nephrotic syndrome is always caused by glomerular disease

23
Q

Clinical features of nephrotic syndrome

A

frothy urine
peripheral oedema
pulmonary oedema
pleural effusions

24
Q

Management of nephrotic syndrome

A

general measures:
- low sodium diet
- fluid restriction
- diuretics
- renin angiotensin aldosterone inhibition and BP control
- statin
- anticoagulation

25
Q

Why is inhibiting angiotensin important in nephrotic syndrome?

A

angiotensin constricts efferent arteriole and increases GFR
inhibition of angiotensin dilates efferent arteriole and decreases GFR
decreases proteinuria

26
Q

Most common cause of nephrotic syndrome in children?

A

minimal change disease

27
Q

Minimal change disease management

A

steroid-responsive

28
Q

Causes of secondary focal segmental glomerulosclerosis

A

obesity
hypertension
HIV
bisphosphonates

29
Q

What happens in membranous nephropathy?

A

glomerular basement membrane immune deposits

30
Q

Causes of primary/idiopathic membranous nephropathy

A

anti-PLA2R

31
Q

Causes of secondary membranous nephropathy

A

hepatitis
malignancy
autoimmune
drugs

32
Q

Microscopic feature of glomerulosclerosis in diabetic nephropathy

A

kimmelstein wilson nodules

33
Q

What is amyloidosis?

A

extracellular deposition of beta sheet fibrils

34
Q
A