Nephrotic syndrome
D E FI N I T ION
Characterized by proteinuria (>3 g/24 h), hypoalbuminaemia (<30 g/L),
oedema and hypercholesterolaemia.
AE T IOLOGY
Commonest cause is minimal change glomerulonephritis in children, but all
forms of glomerulonephritis can cause nephrotic syndrome.
Other causes: Diabetes mellitus, sickle cell disease, amyloidosis, malignancies (lung and GI
adenocarcinomas), drugs (NSAIDs), Alport’s syndrome, HIV infection.
E P IDEMIOLOGY
Most common cause of nephrotic syndrome in children (90%): minimal
change glomerulonephritis (usually seen in boys <5 years, rare in black populations).
Most common causes of nephrotic syndrome in adults: diabetes mellitus, membranous
glomerulonephritis.
H ISTORY
Family history of atopy in those with minimal change glomerulonephritis, family
history of renal disease.
Swelling of face, abdomen, limbs, genitalia.
Symptoms of the underlying cause (e.g. SLE).
Symptoms of complications (e.g. renal vein thrombosis: loin pain, haematuria).
EXAMINA T I ON
Oedema: Periorbital, peripheral, genital.
Ascites: Fluid thrill, shifting dullness.
PATHOLOGY/PATHOGENESI S
Structural damage to the basement membrane or the
reduction in the negatively charged components within it reduces the filtration of large
protein molecules by the glomerulus, causing proteinuria and hypoalbuminaemia.
INVE S T I G A T IONS
Blood: FBC, U&E, LFT (# albumin), ESR/CRP, glucose, lipid profile
(secondary hyperlipidaemia), immunoglobulins, complement (C3, C4).
Tests to identify the underlying cause of glomerulonephritis:
SLE: ANA, anti-dsDNA.
Infections: Group A b-haemolytic streptococcal infection (ASO titre), HBV infection (serology),
plasmodium malariae (blood films).
Goodpasture’s syndrome: Anti-glomerular basement membrane antibodies.
Vasculitides: e.g. Wegener’s and microscopic polyarteritis (ANCA).
Urine: Urinalysis (protein, blood), microscopy, culture, sensitivity, 24-h collection (to calculate
creatinine clearance and 24-h protein excretion).
Renal ultrasound: Excludes other renal diseases that may cause proteinuria, e.g. reflux
nephropathy.
Renal biopsy: In all adults and in children who have unusual features or do not respond to
steroids.
Other imaging: Doppler ultrasound, renal angiogram, CT or MRI are options if renal vein
thrombosis is suspected.
MANAGEMENT
Treat oedema:
. Fluid restriction (1 L/day),
. Naþ restriction (50 mmol/day),
. diuretics (e.g. oral furosemidemetolazone or spironolactone),
. occasionally, IV diuretics and salt-poor albumin may be required for initiation of diuresis.
Treat the cause:
. Minimal change glomerulonephritis: High-dose steroids (60mgfor 2months) and gradually
# the dose, treat relapses (40% within 3 years) with steroids, immunosuppressants:
cyclophosphamide or ciclosporin for steroid non-responders or those with relapses.
. Membranous glomerulonephritis: The benefit of steroids and immunosuppressants is
uncertain.
. SLE: Corticoteroids, cyclophosphamide.
NEPHROLOGY
123
Nephrotic syndrome (continued)
Monitor:
. BP, U&E, weight, fluid balance.
. Thromboprophylaxis: Heparin.
COMPL I C A T IONS
Renal failure (caused by hypovolaemia especially following diuretics,
renal vein thrombosis, progression of underlying renal disease), " susceptibility to infection
(e.g. peritonitis, pneumococcal because of loss of immunoglobulins and lipid content in the
urine), thrombosis (e.g. renal vein and DVT caused by hypovolaemia and hypercoagulable
state caused by loss of antithrombin in the urine and " synthesis of fibrinogen in the liver),
hyperlipidaemia (possibly caused by " synthesis of trigylcerides and cholesterol along with
albumin in the liver).
P ROGNOS I S
Varies according to the underlying condition and presence of complications
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