Nephrotic Syndrome + Glomerulonephritis Flashcards
Proteinuria
Represents abnormal glomerular filtration barrier function (as this is what is supposed to keep proteins out of urine)
Normal proteinuria
<150mg/day (around 30mg is albumin)
Microalbuminuria
30-300mg/day
ACR= 3-30mg/mmol
Macroalbuminuria
> 300mg/day
ACR= >30mg/mmol
Asymptomatic proteinuria
<3g/day
Nephrotic range proteinuria
> 3g/day
Proteinuria measurement- Urine Dipstick
Trace= 15-30mg/dL 1+= 30-100mg/dL 2+= 100-300mg/dL 3+= 300-1000mg/dL 4+= >1000mg/dL Will show up +ve if protein >300mg/day Convenient and easy Protein excretion not consistent throughout day Only albumin detected False negatives in multiple myeloma (protein component not albumin)
Proteinuria measurement- ACR/PCR
Daily creatinine excretion almost constant 910mmol/day)
Therefore ACR/PCR corrects for changes in urine conc. throughout day
First morning specimen most accurate
Can multiply PCR/ACR x 10 to obtain approx. value for 24hr excretion
Limitations- extremes of muscle mass, collection timing
24 hour urine collection- proteinuria
Gold standard
Impractical + difficult
Figure precise but often not necessary
Different causes of oedema- pathophysiological mechanisms
Increased hydrostatic pressure
Decreased oncotic pressure
Increased capillary permeability
Lymphatic blockage
Oedema- underfill hypothesis
Decrease in intravascular colloid oncotic pressure due to hypoalbuminuria
Leads to intravascular vol. depletions
Results in overactivation RAAS–> salt and water retention
Oedema- overfill hypothesis
Primary mechanism in nephrotic syndrome
Sodium retention is primary event due to increased Na/K ATPase activity in collecting duct
Leads to expansion of intravascular volume that increases hydrostatic pressure to force more fluid into interstitial space
Nephrotic syndrome
Clinical syndrome arising from failure of glomerular filtration barrier to restrict passage of proteins into Bowman’s space
Proteinuria (>3g/day) associated with hypoalbuminuria (<30g/L), generalised oedema, hyperlipidaemia + thrombotic tendency
Nephritic syndrome
Clinical syndrome associated with underlying glomerulonephritis (inflammation of glomerulus)
Haematuria, mild proteinuria, hypertension, impaired renal function, oliguria + mild oedema
Nephrotic syndrome diagnostic criteria
Proteinuria >3g/day
Hypoalbuminuria <30g/L
Generalised oedema
Hypercholesterolaemia
Nephrotic syndrome clinical history
Generalised oedema
Frothy urine
Collateral history- previous history, OTC NSAIDS, fam history renal disease, weight loss etc
Nephrotic syndrome Investigations
Exam- peripheral + sacral oedema, periorbital oedema, ascites, pleural effusions
BP- can be normal, low or raised
Urine dipstick- protein 4+, blood may be + or -
Nephrotic syndrome differential diagnoses
Minimal change disease Focal segmental glomerulosclerosis Membranous nephropathy Amyloidosis Diabetic nephropathy
Minimal change disease- nephrotic syndrome
Most common cause nephrotic syndrome in children
Idiopathic
Secondary to- recent resp. infection, immunisation, NSAIDs, haematological malignancy
Massive oedema- facial + periorbital swelling, ascites, pleural + pericardial effusions
Absence of microscopic haematuria
BP= low/normal
Light microscopy= normal
Electron microscopy= effacement of podocyte end-feet
Treatment= corticosteroids
Focal segmental glomerulosclerosis- nephrotic syndrome
Most common cause in Hispanic + African American adults
Idiopathic
Secondary to- longstanding hypertension, any chronic kidney condition, HIV, heroin, obesity
Microscopic haematuria often present
BP often raised
Light microscopy- segmental sclerosis + hyalinosis
Electron microscopy- effacement of podocyte end-feet
Treatment- immunosuppression
Nephrotic syndrome- membranous nephropathy
Most common cause primary nephrotic syndrome in Caucasian adults
Most commonly idiopathic
Secondary to- drugs (gold, NSAIDs, penicillamine), infections (HBV, HCV, syphilis), SLE, solid tumours
Microscopic haematuria common
BP often raised
VTE common
Light microscopy- diffuse capillary + GMB thickening
Immunostaining- positive IgG staining
Electron microscopy- subendothelial deposit humps in GBM
Treatment- immunosuppression