Nephritic vs Nephrotic Causes for MRCP Part 1

TL;DR

For MRCP Part 1, differentiating nephritic from nephrotic syndromes is a recurring examination theme. List: Nephritic vs Nephrotic Causes is best remembered by recognising the underlying pattern of glomerular injury, typical clinical features and the diseases that most commonly produce each syndrome. Focus on recognising disease associations, complement levels, biopsy findings and classic examination traps rather than memorising isolated facts.

Why this matters

Many MRCP questions begin with a patient presenting with oedema, haematuria or declining renal function. The challenge is usually not making a definitive pathological diagnosis but recognising whether the presentation is nephritic or nephrotic.

Knowing the distinction allows you to predict:

• Urine findings

• Serum albumin

• Blood pressure

• Complement levels

• Histological patterns

• Common complications

• Appropriate investigations

These clues frequently lead directly to the correct answer.

Core Sections

Nephritic Syndrome: What is it?

Nephritic syndrome results from inflammatory injury to the glomerulus.

Typical features include:

• Haematuria (often microscopic)

• Red cell casts

• Mild-to-moderate proteinuria

• Hypertension

• Reduced GFR

• Oliguria

• Rising serum creatinine

• Fluid retention

Inflammation damages the glomerular capillary wall, allowing red blood cells to leak into urine while reducing filtration.

Nephrotic Syndrome: What is it?

Nephrotic syndrome results primarily from increased permeability of the glomerular filtration barrier.

Typical features include:

• Proteinuria >3.5 g/day

• Hypoalbuminaemia

• Generalised oedema

• Hyperlipidaemia

• Lipiduria

• Increased thrombotic risk

• Increased infection risk

Patients usually have little or no haematuria unless another inflammatory process is present.

High-Yield Comparison Table

Feature	Nephritic Syndrome	Nephrotic Syndrome
Main pathology	Inflammation	Increased permeability
Proteinuria	Mild-moderate	Massive (>3.5 g/day)
Haematuria	Common	Usually absent or mild
RBC casts	Present	Absent
Oedema	Mild	Marked
Blood pressure	Often elevated	May be normal initially
Renal function	Frequently impaired	Often preserved early
Serum albumin	Mild reduction	Marked reduction
Hyperlipidaemia	Uncommon	Characteristic
Major complication	AKI	Venous thrombosis

The 10 High-Yield Causes You Must Know

1. Post-streptococcal glomerulonephritis (Nephritic)

Usually follows streptococcal pharyngitis or skin infection after 1–3 weeks.

Key MRCP clues:

• Low C3

• Cola-coloured urine

• Children more commonly affected

• Subepithelial "hump" deposits

2. IgA Nephropathy (Nephritic)

The commonest primary glomerulonephritis worldwide.

Remember:

• Haematuria occurs within 24–48 hours of an upper respiratory tract infection.

• Complement levels are usually normal.

3. Rapidly Progressive Glomerulonephritis (Nephritic)

An examination favourite.

Major causes include:

• Anti-GBM disease

• ANCA-associated vasculitis

• Immune-complex glomerulonephritis

Biopsy often shows crescents.

4. Lupus Nephritis (Usually Nephritic)

Can present with mixed nephritic-nephrotic features.

Important clues:

• Positive ANA

• Positive anti-dsDNA

• Low complement

5. Membranoproliferative Glomerulonephritis

Produces both nephritic and nephrotic features.

Frequently associated with:

• Hepatitis C

• Cryoglobulinaemia

• Complement abnormalities

6. Minimal Change Disease (Nephrotic)

The commonest nephrotic syndrome in children.

Classic features:

• Selective albuminuria

• Normal light microscopy

• Foot process effacement on electron microscopy

• Excellent steroid response

7. Focal Segmental Glomerulosclerosis (Nephrotic)

Increasingly common in adults.

Associations include:

• HIV

• Obesity

• Heroin use

• Reduced nephron mass

Poorer prognosis than minimal change disease.

8. Membranous Nephropathy (Nephrotic)

Common in adults.

Associations:

• PLA2R antibodies

• Solid tumours

• Hepatitis B

• Certain drugs

Watch for renal vein thrombosis in MRCP questions.

9. Diabetic Nephropathy (Nephrotic)

The commonest cause of nephrotic-range proteinuria worldwide.

Features:

• Long-standing diabetes

• Albuminuria

• Progressive CKD

• Nodular glomerulosclerosis (Kimmelstiel–Wilson lesions)

10. Amyloidosis (Nephrotic)

Produces severe proteinuria.

Think of:

• Multiple myeloma

• Chronic inflammatory diseases

• AA and AL amyloid

The Five Most Tested Subtopics

1. Complement Levels

Low complement:

• Post-infectious GN

• Lupus nephritis

• MPGN

Normal complement:

• IgA nephropathy

• Minimal change disease

• FSGS

• Membranous nephropathy

2. Biopsy Patterns

Know the hallmark appearances:

• Minimal change → Foot process effacement

• Membranous → Thickened basement membrane

• FSGS → Segmental sclerosis

• RPGN → Crescents

• Post-infectious GN → Subepithelial humps

3. Secondary Causes

Frequently examined associations include:

• Diabetes

• SLE

• Hepatitis B

• Hepatitis C

• HIV

• Malignancy

• Amyloidosis

4. Major Complications

Nephritic:

• Acute kidney injury

• Hypertension

• Pulmonary oedema

Nephrotic:

• DVT

• Pulmonary embolism

• Infection

• Hyperlipidaemia

5. Examination Clues

Look for keywords:

• Tea-coloured urine → Nephritic

• Foamy urine → Nephrotic

• Periorbital oedema → Both

• RBC casts → Nephritic

• Massive oedema → Nephrotic

Practical Examples / Mini-Case

Single Best Answer

A 42-year-old man presents with progressive ankle swelling. Urinalysis shows 4+ protein with no haematuria. Serum albumin is 18 g/L and cholesterol is markedly elevated.

Which syndrome best explains these findings?

A. Acute nephritic syndrome

B. IgA nephropathy

C. Nephrotic syndrome

D. Rapidly progressive glomerulonephritis

E. Post-streptococcal glomerulonephritis

Correct answer: C. Nephrotic syndrome

Explanation

Heavy proteinuria, profound hypoalbuminaemia and hyperlipidaemia define nephrotic syndrome. The absence of haematuria or red cell casts makes nephritic disease much less likely.

Practical Study-Tip Checklist

Before your examination, ensure you can answer these confidently:

1. Distinguish nephritic from nephrotic syndrome within 30 seconds.

2. Recall the ten highest-yield causes without prompts.

3. Recognise diseases associated with low complement.

4. Match biopsy findings to the correct diagnosis.

5. Identify common secondary causes.

6. Recognise complications such as renal vein thrombosis.

7. Interpret urine findings accurately.

8. Differentiate nephritic and nephrotic clinical presentations.

9. Answer pathology-image questions using classic histology.

10. Practise timed renal medicine questions in the Free MRCP QBank or complete a mock test before exam day.

Common Pitfalls

• Confusing haematuria with proteinuria as the dominant abnormality.

• Assuming all glomerular diseases produce nephrotic syndrome.

• Forgetting that lupus nephritis may have both nephritic and nephrotic features.

• Mixing up complement patterns between IgA nephropathy and post-infectious GN.

• Forgetting the thrombotic risk associated with nephrotic syndrome.

FAQs

Is nephritic syndrome always associated with haematuria?

Almost always. Microscopic haematuria and red cell casts are characteristic findings because inflammation damages the glomerular capillary wall.

Which nephrotic syndrome is most common in children?

Minimal change disease is the commonest cause of nephrotic syndrome in children and typically responds well to corticosteroids.

Why does nephrotic syndrome cause thrombosis?

Loss of anticoagulant proteins such as antithrombin III in the urine creates a hypercoagulable state, increasing the risk of venous thromboembolism.

Which diseases cause both nephritic and nephrotic features?

Lupus nephritis and membranoproliferative glomerulonephritis frequently produce mixed clinical presentations and are common MRCP examination topics.

Ready to start?

Continue your renal medicine revision with the MRCP Part 1 overview, strengthen your understanding through the Free MRCP QBank, explore MRCP lectures for structured teaching, and assess your readiness using the mock tests.

Sources

1. MRCP(UK). Examination syllabus. https://www.mrcpuk.org/

2. KDIGO Clinical Practice Guideline for Glomerular Diseases. https://kdigo.org/guidelines/glomerular-diseases/

3. Kidney Disease: Improving Global Outcomes (KDIGO). Clinical Practice Guidelines.

4. Davidson's Principles and Practice of Medicine. 24th Edition.

5. Oxford Handbook of Clinical Medicine. Latest Edition.