10 nephrotic syndrome facts
Key Points
-
Nephrotic syndrome is a chronic kidney disorder characterised by excessive proteinuria, hypoalbuminaemia, hyperlipidaemia, and oedema.
- It is a glomerular disease.
- There are primary (mainly chronic glomerulonephritis) and secondary (e.g. diabetes) causes.
-
Prompt recognition and treatment are crucial to prevent long-term kidney damage and complications.
1. Definition
Nephrotic syndrome is a collection of symptoms resulting from kidney damage, specifically glomerular injury, leading to:
-
Proteinuria (excessive protein loss in urine): ACR >220 mg/mmol (normal is <3).
-
Hypoalbuminaemia (low serum albumin): <30g/L.
Note. Hypoalbuminaemia is not primarily due to proteinuria. -
Oedema.
2. Epidemiology
-
Primary causes (see below) of nephrotic syndrome are rare.
- Minimal change disease (MCD) is the commonest cause in children.
3. Risk Factors
-
Obesity.
-
Diabetes.
-
Infections (e.g. HIV, hepatitis B/C).
-
Autoimmune disorders (e.g. lupus, SLE).
4. Causes
- Primary. Most are types of chronic glomerulonephritis, e.g.
- Mesangiocapillary Glomerulonephritis: Rare, but can be associated with infections or autoimmune disorders.
- Focal Segmental Glomerulosclerosis (FSGS): Leading cause in adults.
- Membranous Nephropathy: Second most common cause in adults.
- Minimal Change Disease (MCD): Most common cause in children, accounting for 80% of cases
- Secondary: Associated with underlying conditions (e.g. diabetes, amyloid, lupus (SLE), infections (HIV, Hep B/C, malaria), pre-eclampsia and eclampsia).
5. Symptoms
-
Oedema (swelling, particularly around eyes (peri-orbital) and ankles).
-
Weight gain.
-
Fatigue.
-
Foamy urine (proteinuria).
-
Signs of hyperlipidemia (elevated cholesterol).
6. Diagnosis
- May be clinical when cause obvious (e.g diabetes, pregnancy).
- Otherwise a renal biopsy is needed. This is the gold standard for diagnosis.
Investigation
- Urine dipstick: Proteinuria and haematuria.
- Urinary ACR: Needed for diagnosis (see above).
- Blood tests (simple): FBC, CRP, U+E, LFT, bone, glucose.
- Renal immunology: E.g. ANA, dsDNA, phospholipase A2 receptor (PLA2R) antibody.
- Imaging: Ultrasound, CT, or MRI (to rule out obstructive causes, and in preparation for renal biopsy).
- Renal biopsy: When cause uncertain (most primary cases in adults).
Differential Diagnosis
-
Nephritic syndrome.
-
Chronic kidney disease (CKD).
Note. Can have both NS and CKD (and AKI) -
Chronic heart failure (CHF).
-
Liver disease.
7. Treatment
- Diuretics: For oedema.
- Fluid restriction: For oedema.
- Corticosteroids: First-line treatment for MCD.
- Immunosuppressants: For some GNs (e.g. IgA and membranous nephropathy).
-
ACE inhibitors/ARBs (e.g. ramipril/losartan): To reduce proteinuria.
- SGLT2i (e.g. dapagliflozin): To reduce proteinuria.
-
HMG CoA reductase inhibitor (statin): For hyperlipidemia.
- Anticoagulation: If serum albumin <20 g/L.
Note 1. MCD in children is usually successfully treated with prednisolone. It then usually goes away. A renal biopsy is usually not done in children with NS.
Note 2. There is no evidence that limiting protein in the diet helps to reduce the protein loss in the urine.
8. Complications
- Hypertension.
- Fluid overload (including pleural effusion).
- Infection: Increased risk due to disease and immunosuppression.
- Thrombosis: Hypercoagulability leading to DVT/PE, renal vein thrombosis (can be bilateral).
-
Acute kidney injury: Rapid worsening of kidney function.
-
Chronic kidney disease.
-
End-stage renal failure (ESRF).
9. Prognosis
-
Variable: depending on underlying cause and response to treatment – e.g. for eclampsia, delivery of baby almost always reverses NS.
-
MCD: Generally good prognosis with steroid treatment.
-
FSGS: More guarded prognosis.
10. Prevention
-
Control blood pressure.
-
Maintain healthy weight.
-
Manage diabetes.
-
Avoid nephrotoxic agents.
-
Regular monitoring for patients with underlying risk factors.
Summary
We have described 10 facts about nephrotic syndrome. We hope it has been helpful.
