Minimal-change disease

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Minimal change disease is a podocytopathy in which the filtration barrier loses albumin despite little visible abnormality on routine microscopy. The name describes the light-microscopy appearance, not the clinical severity. Adults may present with disabling oedema, profound biochemical change, thrombosis, infection and AKI. Electron microscopy is therefore essential to the biopsy interpretation, and sampling must also exclude an unsampled FSGS lesion.

The distinction between primary and secondary MCD changes care. A temporal relationship with an NSAID or immune checkpoint inhibitor, a systemic allergic or infectious syndrome, or constitutional and lymph-node features suggesting Hodgkin lymphoma prompts withdrawal and cause-directed management. Screening is guided by history rather than indiscriminate scans, but an adult with atypical features, poor response or relapse deserves renewed secondary-cause review.

Glucocorticoid sensitivity is characteristic but not immediate. KDIGO permits a high-dose course for up to 16 weeks in adults before declaring resistance, although the exact duration is individualised for response and toxicity. Once complete remission is achieved, the dose is tapered rather than stopped abruptly. Recurrent courses can cause diabetes, infection, osteoporosis, cataract, mood and cardiovascular harm, so steroid-sparing therapy becomes central in frequent relapsers and steroid-dependent disease.

Key points

Minimal change disease causes a selective or predominantly albuminuric nephrotic syndrome through podocyte foot-process injury without immune-complex deposition.
Light microscopy is normal or nearly normal, immunofluorescence is negative or nonspecific, and electron microscopy shows diffuse podocyte foot-process effacement.
Children with a typical steroid-sensitive nephrotic presentation may be treated without initial biopsy, whereas adults usually need tissue confirmation before immunosuppression.
Adults can develop abrupt anasarca, severe hypoalbuminaemia, venous thrombosis and acute kidney injury; AKI is especially recognised in older adults with marked oedema.
Primary disease is often idiopathic, but NSAIDs, lithium, interferon, immune checkpoint inhibitors, infection, allergy and Hodgkin lymphoma are notable secondary associations.
NSAID-associated minimal change may coexist with acute interstitial nephritis, so rash, eosinophilia and pyuria are helpful but often absent.
Initial adult treatment is high-dose oral glucocorticoid under nephrology care, continued until remission or a maximum exposure window before gradual taper.
Adult response can take substantially longer than childhood response; failure to remit by the specialist-defined treatment limit triggers adherence and pathology review, not endless steroid escalation.
Frequent relapse or steroid dependence can be treated with cyclophosphamide, rituximab, a calcineurin inhibitor or a mycophenolic-acid analogue chosen around toxicity and patient priorities.
Thrombotic prophylaxis is individualised from albumin, histology-independent risks, bleeding and planned biopsy; oedema alone is not an indication for anticoagulation.
Supportive care includes careful sodium restriction and diuresis, infection prevention, blood-pressure and lipid assessment, vaccination and avoidance of the triggering medicine.
Relapse is detected through renewed quantitative proteinuria and falling albumin; isolated ankle swelling or a home dipstick should be confirmed and alternative causes considered.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Idiopathic immune-mediated disease

Many cases lack an identified trigger and reflect reversible podocyte signalling dysfunction rather than immune-complex deposition or fixed glomerular scarring.

Medicine-associated disease

NSAIDs, lithium, interferon and immune-checkpoint inhibitors can produce a minimal-change phenotype, with NSAIDs sometimes causing concurrent acute interstitial nephritis.

Infection, allergy or malignancy association

Infections, allergic immune activation and Hodgkin lymphoma are recognised contexts, so systemic symptoms and exposure timing should guide targeted investigation.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Podocyte signalling disturbance
Immune dysregulation or implicated exposures disturb podocyte cytoskeleton and slit-diaphragm function without substantial immunoglobulin or complement deposition.
2
Foot-process effacement
Podocyte extensions broaden and fuse on electron microscopy, removing normal filtration selectivity while light microscopy remains nearly normal.
3
Albumin-predominant protein loss
The altered barrier leaks large quantities of albumin, lowering plasma oncotic pressure and promoting renal sodium retention and generalised oedema.
4
Reversible or relapsing course
Filtration-barrier function can recover with disease control, but recurrent disease may repeatedly restore protein leakage and expose patients to cumulative treatment toxicity.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Abrupt nephrotic presentation

Rapid weight gain, periorbital and dependent oedema, frothy urine, very heavy proteinuria and low albumin with a bland sediment fit MCD but are not histologically specific.

Acute kidney injuryRed flag

Oliguria and rising creatinine can accompany severe nephrosis through underfilling, tubular or interstitial oedema, sepsis, thrombosis or nephrotoxic exposure and require urgent cause assessment.

Venous thrombosisRed flag

New pleuritic pain, hypoxia, asymmetric swelling, flank pain or haematuria can represent pulmonary, limb or renal-vein thrombosis and demands an urgent VTE pathway.

NSAID-associated disease

Nephrotic syndrome after prescribed or over-the-counter NSAID exposure, sometimes with AKI or sterile pyuria, suggests a secondary podocyte and interstitial lesion.

Hodgkin lymphoma clue

Persistent lymphadenopathy, night sweats, pruritus or weight loss with MCD warrants age- and finding-appropriate malignancy assessment rather than assuming idiopathic disease.

Steroid toxicity

Fever, hyperglycaemia, proximal weakness, mood change, fracture or visual symptoms during a prolonged course may be treatment harm and should not be attributed automatically to nephrosis.

Relapse pattern

Recurrent heavy proteinuria after complete remission defines relapse; frequency, timing during taper and cumulative adverse effects determine steroid-sparing need.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Urine PCR, ACR and microscopyFirst step
Why
Quantify protein loss, assess albumin predominance and identify inflammatory or glomerular mimics.
Interpretation and limitations
MCD usually has a bland sediment, although microscopic haematuria can occur; casts or disproportionate non-albumin protein prompt reconsideration.
02
Creatinine, electrolytes and albumin
Why
Grade nephrotic severity, AKI and biochemical risk before diuresis or immunosuppression.
Interpretation and limitations
Assess trend and perfusion because an oedematous patient may be intravascularly depleted; severe albumin reduction also increases thrombosis concern.
03
Full blood count, CRP, glucose and lipid profile
Why
Find infection, establish steroid-safety baselines and document nephrotic metabolic effects.
Interpretation and limitations
Inflammation or cytopenia suggests a secondary process; glucose and lipids need reassessment as nephrosis and steroid exposure change.
04
Cause-directed immune and infection screen
Why
Exclude lupus, chronic viral infection and other secondary nephrotic conditions when clinical probability warrants.
Interpretation and limitations
There is no diagnostic blood marker for MCD; serology narrows alternatives but biopsy establishes the lesion.
05
Medicine and exposure reconciliation
Why
Identify NSAIDs, lithium, interferon, immune checkpoint therapy and other temporal triggers.
Interpretation and limitations
Include non-prescription analgesics and supplements and record when exposure started and stopped; dechallenge supports but does not prove causation.
06
Kidney biopsy with electron microscopy
Why
Confirm diffuse foot-process effacement and exclude FSGS, membranous nephropathy and immune deposits.
Interpretation and limitations
A near-normal light-microscopy sample supports MCD only after adequate sampling and electron-microscopy review; focal lesions can be missed.
07
VTE imaging when symptomatic
Why
Diagnose pulmonary, limb or renal venous thrombosis during high-risk active nephrosis.
Interpretation and limitations
Do not rely on oedema distribution or D-dimer alone; select imaging through the local VTE pathway and current kidney function.
08
Secondary malignancy assessment
Why
Investigate lymphadenopathy, constitutional symptoms or an atypical treatment course.
Interpretation and limitations
Use clinical findings and age-appropriate pathways rather than routine whole-body imaging for every otherwise typical case.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Focal segmental glomerulosclerosis

Both show foot-process effacement, but segmental scars, adaptive risk factors or persistent treatment resistance support FSGS; sampling can miss early focal lesions.

Membranous nephropathy

Capillary-wall thickening, subepithelial deposits and disease-associated antibodies favour membranous disease rather than negative or nonspecific immunofluorescence.

NSAID-associated interstitial nephritis

Pyuria and interstitial inflammation may coexist with minimal-change nephrosis after NSAID exposure, so biopsy compartments and renal trajectory must be integrated.

Diabetic or amyloid nephropathy

A gradual course, systemic deposition features or characteristic glomerular deposits indicates a structural secondary cause rather than isolated minimal-change podocyte dysfunction.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Adult nephrotic syndromeConfirm MCD before treatmentFirst stepAn adult has new heavy proteinuria, hypoalbuminaemia and oedema with a possible minimal-change phenotype.

1Assess fluid and perfusion, infection, VTE and AKI, quantify protein and review NSAIDs, cancer therapies, allergy, infection and malignancy clues.
2Send focused secondary tests and arrange native kidney biopsy with adequate immunofluorescence and electron microscopy, correcting blood pressure and bleeding risk.
3Begin cause-specific and glucocorticoid treatment only after nephrology integrates biopsy and clinical context; stop a plausible trigger safely with the prescribing team.

02Initial remissionUse glucocorticoid with boundariesBiopsy-supported primary MCD is suitable for oral glucocorticoid treatment.

1Document baseline infection, glucose, bone, mental-health, eye and reproductive risk and prescribe prophylaxis and vaccination measures appropriate to planned exposure.
2Use the specialist high-dose regimen while monitoring quantitative protein and albumin, allowing the slower adult response but not exceeding the agreed maximum course without review.
3After complete remission, taper gradually over the renal protocol and reduce diuretic and anticoagulation intensity as albumin, fluid state and clot risk recover.

03No remissionChallenge steroid resistanceNephrosis persists despite a verified adequate glucocorticoid course or toxicity prevents completion.

1Confirm adherence, dose, absorption, protein trajectory and ongoing secondary exposure and check for infection or steroid complications.
2Request renal-pathology review for sampling adequacy and missed FSGS or another lesion, considering repeat biopsy or genetic evaluation where the phenotype has changed.
3AlternativeSelect an alternative or steroid-sparing treatment only through nephrology, using toxicity, fertility, kidney function and patient preference to choose the agent.

04Frequent relapseReduce cumulative steroid harmRelapses are frequent, occur during taper or create unacceptable glucocorticoid toxicity.

1Confirm each relapse quantitatively, identify infection or medicine triggers and calculate cumulative glucocorticoid exposure and complications.
2Discuss cyclophosphamide, rituximab, calcineurin inhibitor or mycophenolic-acid therapy, explaining likely course, monitoring, reproductive and infection trade-offs.
3Create a written relapse and sick-day plan, preserve vaccination and bone health, and follow remission after treatment ends because late recurrence still occurs.

Key medicines and prescribing safety5 treatments · regimens, roles and cautions

First-line immunosuppression induces complete remission in most adults with biopsy-proven primary minimal change disease.

Prednisolone

KDIGO high-dose daily or alternate-day treatment is specialist prescribed for up to the response limit, then tapered after remission.

Infection, diabetes, mood disturbance, hypertension, osteoporosis, cataract and adrenal suppression require proactive prevention and a defined taper rather than repeated unreviewed courses.

Provides a steroid-sparing option for frequently relapsing or steroid-dependent MCD in selected adults.

Rituximab

Use a specialist intravenous induction schedule with screening, premedication and any re-dosing based on the renal plan.

Infusion reaction, hepatitis B reactivation, hypogammaglobulinaemia and infection require vaccine timing, viral screening, immunoglobulins and blood-count review.

Can maintain remission when glucocorticoids are ineffective, contraindicated or produce dependency.

Calcineurin inhibitor

Tacrolimus or ciclosporin is dosed and trough-monitored according to the specialist nephrotic-syndrome protocol.

Nephrotoxicity, hypertension, hyperkalaemia, neurotoxicity and major interactions complicate interpretation of a creatinine rise; relapse can follow withdrawal.

May produce durable remission in frequently relapsing or steroid-dependent disease when its toxicity is acceptable.

Cyclophosphamide

A finite specialist oral or intravenous course is selected by age, kidney function and cumulative exposure.

Marrow suppression, infection, infertility, teratogenicity, bladder damage and malignancy require counselling, contraception, blood counts and exposure limits.

Relieves symptomatic fluid accumulation while disease-directed treatment closes the glomerular protein leak.

Loop diuretic

Titrate oral or intravenous dosing to oedema, perfusion, kidney function and previous diuretic exposure.

Visible oedema can coexist with low circulating volume; monitor weight, pressure, sodium, potassium and creatinine to prevent over-diuresis.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Acute kidney injury

Marked oedema, reduced effective circulating volume and interstitial pressure can sharply lower filtration, especially in older adults with severe hypoalbuminaemia.

Venous thromboembolism

Nephrotic loss of anticoagulant proteins, increased hepatic procoagulants and immobility together raise thrombosis risk during active disease.

Serious infection

Urinary immunoglobulin loss, oedematous tissue and immunosuppressive treatment can impair defence against bacterial and opportunistic infection.

Frequent relapse or treatment dependence

Repeated proteinuric relapses expose patients to oedema and nephrotic complications, while cumulative immunosuppression adds metabolic, infectious and reproductive harm.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

During active nephrosis track weight, oedema, breathlessness, blood pressure, postural symptoms and urine output while adjusting diuretics.
Measure urine PCR, serum albumin and eGFR serially to document complete or partial remission and detect relapse rather than relying on appearance.
During glucocorticoid treatment monitor infection, glucose, pressure, weight, mood, muscle, bone and eye toxicity and confirm that the planned taper is followed.
For rituximab review immunoglobulins, blood count, infection and hepatitis status and time vaccinations before B-cell depletion when possible.
For a calcineurin inhibitor follow trough exposure, creatinine, potassium, magnesium, pressure and interacting medicines through renal pharmacy.
Reassess secondary causes when disease is treatment-resistant, unusually recurrent or accompanied by new systemic, lymph-node or inflammatory features.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Minimal histology, major illness

The deceptively normal light-microscopy appearance can accompany anasarca, thrombosis, infection and dialysis-requiring AKI; the name does not describe clinical severity.

Electron microscopy completes diagnosis

Diffuse foot-process effacement supports a podocytopathy, while adequate light-microscopy sampling is still needed to avoid missing a focal sclerotic lesion.

Adult response is slower

Children often remit promptly, whereas an adult may require many weeks; this justifies patience within a bounded course, not indefinite high-dose prednisolone.

NSAIDs produce a dual lesion

Medication-associated MCD may coexist with acute interstitial nephritis and substantial AKI even when classic allergic features are absent.

Relapse does not equal failure

Steroid sensitivity may persist across relapses, but cumulative toxicity rather than inability to remit often drives the choice of steroid-sparing therapy.

Diuretic need collapses in remission

As albumin rises and sodium retention resolves, continuing the acute diuretic dose can cause abrupt depletion, so active down-titration is part of recovery.

11Common pitfallsFrequent interpretation and management errors.

01
Giving empirical high-dose prednisolone to an adult with unbiopsied nephrotic syndrome.
02
Interpreting a normal light-microscopy report without confirming electron microscopy and adequate sampling.
03
Calling persistent adult proteinuria steroid-resistant after only a few days of treatment.
04
Continuing high-dose glucocorticoid beyond the agreed response limit without pathology and adherence review.
05
Missing an over-the-counter NSAID, immune checkpoint inhibitor or Hodgkin lymphoma clue in a supposedly idiopathic case.
06
Failing to reduce diuretic or thrombosis-prevention treatment as remission corrects the nephrotic physiology.