Scleroderma renal crisis

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

Scleroderma renal crisis is an abrupt renal vasculopathy occurring mainly in early diffuse systemic sclerosis. A rapid relative rise in blood pressure is typical, but the absolute value can remain within a population reference range and a minority present normotensive. Kidney injury may accompany headache, visual change, hypertensive retinopathy, encephalopathy, left-ventricular failure, pulmonary oedema and microangiopathic haemolytic anaemia. The safest diagnostic response is to recognise the risk phenotype and compare with personal pressure and creatinine baselines.

The pathophysiological driver is profound renal arteriolar narrowing and ischaemia with renin-angiotensin activation. This explains the exceptional benefit of ACE inhibition and why an ordinary antihypertensive is not an equivalent substitute. Short-acting captopril permits rapid titration in the acute phase. Blood pressure should be reduced purposefully toward baseline under close monitoring, not crashed indiscriminately. Creatinine frequently rises initially; continuing ACE inhibition remains central unless a true contraindication such as angioedema or refractory shock exists.

MAHA and thrombocytopenia occur because renal and systemic small vessels are injured. TTP, complement-mediated HUS, malignant hypertension from another cause, ANCA vasculitis, pre-eclampsia and sepsis can resemble the presentation. Send ADAMTS13 and other focused tests when indicated, and use kidney biopsy only when an atypical diagnosis would change treatment and the patient is stable enough. Plasma renin is not required to begin care.

Many patients need dialysis, but renal recovery can occur for up to one or two years, particularly when ACE inhibition is maintained. Transplant assessment is therefore usually delayed until recovery potential is clearer. Prevention depends on avoiding unnecessary high-dose glucocorticoid, educating high-risk patients to measure pressure and arranging immediate access after a rise. Routine prophylactic ACE inhibition before crisis is not recommended.

Key points

Suspect renal crisis in systemic sclerosis when blood pressure rises relative to personal baseline with AKI, headache, retinopathy, encephalopathy, heart failure or MAHA.
Risk is highest in early rapidly progressive diffuse cutaneous disease, anti-RNA-polymerase-III positivity and recent higher-dose glucocorticoid exposure.
Measure pressure in both arms, repeat manually, compare with previous readings and obtain creatinine, potassium, urine, blood film, platelets, LDH and haptoglobin immediately.
Start short-acting captopril promptly on clinical suspicion; do not wait for antibody results, biopsy or plasma-renin measurement.
Titrate captopril frequently in monitored care toward the pre-crisis pressure while avoiding symptomatic hypotension; rising creatinine alone is not a reason to withdraw the ACE inhibitor.
Add other antihypertensives when pressure remains high after ACE-inhibitor optimisation, but do not replace the ACE inhibitor with another class as the core treatment.
Dialyse for standard urgent indications and continue ACE inhibition if tolerated; kidney recovery may occur after months, so transplant decisions are usually deferred.
Test for TTP and other TMA, ANCA vasculitis, infection and obstruction when the phenotype is atypical, but pursue these in parallel rather than delaying captopril.
Do not prescribe prophylactic ACE inhibitor solely to prevent renal crisis; it has not shown preventive benefit and may mask the pressure signal or associate with worse outcomes.
After recovery, continue specialist ACE inhibition, blood-pressure self-monitoring and renal follow-up, and avoid unnecessary glucocorticoid exposure.

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

High-risk systemic sclerosis phenotype

Early rapidly progressive diffuse skin disease, anti-RNA-polymerase-III antibodies, tendon friction rubs, anaemia and cardiac involvement associate with greatest renal-crisis susceptibility.

Glucocorticoid exposure

Higher-dose systemic glucocorticoid, often cited above prednisolone 15 mg/day, is an important modifiable association and should be avoided or tightly justified.

Vascular and haemodynamic triggers

Endothelial injury, vasospasm, cardiac compromise, dehydration and other acute stress may precipitate renal arteriolar narrowing in an already vulnerable vascular bed.

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

1
Renal arteriolar narrowing
Intimal proliferation, endothelial injury and vasospasm reduce renal perfusion, producing ischaemia and abrupt activation of the renin-angiotensin-aldosterone system.
2
Renin-driven pressure spiral
Angiotensin-II-mediated vasoconstriction and sodium retention raise pressure, which further damages vessels and kidneys and drives a self-amplifying emergency.
3
Thrombotic microangiopathy
Severe endothelial injury fragments red cells and consumes platelets in small vessels, causing MAHA that overlaps phenotypically with TTP and complement-mediated TMA.
4
Acute injury and delayed recovery
Cortical ischaemia can require dialysis, yet renal function may recover over many months if ACE inhibition and supportive care are sustained.

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

Relative pressure rise

A rise from a previously low personal baseline can signal crisis before pressure reaches a conventional malignant-hypertension threshold.

Acute kidney injury

Creatinine increases over hours to days with proteinuria or haematuria that is usually modest compared with severe glomerulonephritis.

Renin-driven organ injuryRed flag

Headache, blurred vision, retinopathy, encephalopathy, chest pain and pulmonary oedema indicate severe vascular pressure injury.

Microangiopathic haemolysis

Schistocytes, platelet fall, raised LDH and low haptoglobin support TMA but do not by themselves distinguish renal crisis from TTP.

High-risk phenotype

Rapid diffuse skin progression, anti-RNA-polymerase-III, tendon friction rubs and recent glucocorticoid exposure should lower the diagnostic threshold.

Normotensive crisisRed flag

AKI and MAHA without a large measured pressure rise remains possible, especially when ACE inhibition or cardiac dysfunction modifies presentation.

Red flags requiring action

A systolic pressure rise of at least 20 mmHg or diastolic rise of at least 10 mmHg from usual can be important even when the absolute value appears modest.
Headache, visual disturbance, confusion, seizure, retinal change, pulmonary oedema, chest pain or oliguria indicates hypertensive organ injury requiring immediate monitored treatment.
Falling platelets, schistocytes, raised LDH and low haptoglobin indicate microangiopathic haemolysis and require parallel TMA assessment.
Normotensive AKI can still be renal crisis, especially after ACE-inhibitor exposure, but carries a wider differential and often worse prognosis.
Pregnancy with hypertension and AKI requires simultaneous assessment for pre-eclampsia, renal crisis, TMA and lupus nephritis.

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
Serial manual blood pressureFirst step
Why
Confirm trajectory, guide captopril titration and identify hypertensive organ risk.
Interpretation and limitations
Compare with prior baseline and both arms; a clinically important relative rise can occur below 140/90 mmHg.
02
Creatinine, electrolytes, eGFR and urinalysis
Why
Stage AKI, detect potassium or fluid emergencies and compare the sediment with glomerulonephritis.
Interpretation and limitations
Protein and blood are often mild; heavy active sediment or nephrotic protein suggests an alternative or additional renal process.
03
FBC, film, platelets, LDH, bilirubin and haptoglobin
Why
Identify MAHA and thrombocytopenia and quantify microangiopathic severity.
Interpretation and limitations
Schistocytes support TMA; send ADAMTS13 urgently when TTP is possible because treatment cannot wait for a later result.
04
ECG, troponin, chest imaging and echocardiography
Why
Assess pulmonary oedema, myocardial injury, arrhythmia and alternative cardiopulmonary deterioration.
Interpretation and limitations
Volume overload, primary myocardial fibrosis and PAH may coexist and alter fluid removal and blood-pressure tolerance.
05
Targeted ANCA, complement, cultures and pregnancy tests
Why
Evaluate credible mimics without delaying ACE inhibition for a classic crisis.
Interpretation and limitations
Select tests from phenotype; ANCA positivity needs clinical and biopsy correlation, and infection can trigger or accompany deterioration.
06
Kidney biopsy in atypical stable cases
Why
Distinguish renal crisis vasculopathy from glomerulonephritis or another TMA when uncertainty changes therapy.
Interpretation and limitations
Biopsy is not required for a typical unstable presentation and bleeding or pressure risk may make immediate sampling unsafe.

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

TTP or complement-mediated TMA

Profound thrombocytopenia, neurological features, severe ADAMTS13 deficiency or complement-mediated disease can resemble crisis and requires urgent haematology investigation and distinct treatment.

ANCA glomerulonephritis

Active urinary sediment, systemic vasculitis features and ANCA support pauci-immune glomerulonephritis; biopsy may be needed in a stable atypical case.

Lupus nephritis or other AKI

Immune-complex nephritis, sepsis, obstruction, hypovolaemia, interstitial nephritis and calcineurin toxicity produce renal decline through mechanisms not corrected by ACE inhibition alone.

Pregnancy hypertensive disease

Pre-eclampsia and HELLP share pressure, AKI, haemolysis and thrombocytopenia; gestation, placental findings, liver tests and systemic-sclerosis trajectory inform joint management.

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

01Immediate treatmentStart captopril on suspicionFirst stepSystemic sclerosis is accompanied by a relative pressure rise and acute kidney or hypertensive organ injury.

1Admit to monitored care, repeat pressure, assess urine output, fluid, neurological, retinal and cardiac status, and send renal, potassium and haemolysis studies.
2Give short-acting captopril immediately unless a true contraindication exists and titrate every several hours toward the previous pressure while watching symptoms, potassium and perfusion.
3Add another antihypertensive only after ACE-inhibitor optimisation when needed, treat pulmonary oedema or seizure and involve renal and rheumatology teams at once.

02TMA differentialTreat competing emergencies in parallelMAHA, severe thrombocytopenia, neurological findings or an atypical urine pattern complicates suspected crisis.

1Send ADAMTS13 before plasma therapy where possible, coagulation and haemolysis studies, complement and phenotype-directed ANCA, infection and pregnancy investigations.
2Continue captopril for a credible renal crisis while haematology decides whether immediate plasma exchange for suspected TTP or another TMA treatment is required.
3Use biopsy only after stabilisation when histology will distinguish vasculopathy from glomerulonephritis or another mechanism and procedural risk is acceptable.

03Dialysis and recoverySupport kidneys without abandoning ACE inhibitionHyperkalaemia, acidosis, pulmonary oedema, uraemia or oliguria meets kidney-replacement indications.

1Start haemodialysis or continuous therapy according to physiology, coordinating ultrafiltration with cardiac and blood-pressure tolerance.
2Continue ACE inhibition during dialysis when tolerated and follow urine output, creatinine, pressure and recovery over months rather than declaring immediate end-stage failure.
3Delay irreversible transplant decisions until the reasonable recovery window is assessed, then evaluate recurrence risk and systemic organ suitability.

04Prevention and follow-upDetect the next rise earlyA high-risk systemic-sclerosis patient has not had crisis or has survived an episode.

1Avoid unnecessary high-dose glucocorticoid and give a home monitor with written personal pressure thresholds and an immediate contact route.
2Do not start ACE inhibitor solely as prophylaxis; use it for another clear indication only after specialist consideration of monitoring implications.
3After crisis continue ACE inhibition, renal and cardiovascular monitoring and medication review, and address dialysis access or transplant only if recovery does not occur.

Key medicines and prescribing safety3 treatments · regimens, roles and cautions

Treatment of choice for suspected scleroderma renal crisis because short-acting ACE inhibition interrupts the renin-driven vascular spiral and permits frequent titration.

Captopril

Give 6.25–12.5 mg orally immediately, then repeat and titrate every four to eight hours under monitored specialist care; doses may be increased rapidly toward 25–50 mg three times daily as pressure and potassium permit.

Do not stop solely because creatinine rises. Monitor pressure, potassium, renal function and perfusion closely; avoid in previous ACE-inhibitor angioedema and manage shock individually. It is fetotoxic after early pregnancy and pregnancy requires immediate expert substitution.

Additional vasodilator when blood pressure remains above the acute target despite appropriately titrated captopril.

Amlodipine add-on

Start 5 mg orally once daily and increase to 10 mg once daily if required after ACE-inhibitor optimisation and according to pressure response.

It does not replace ACE inhibition. Monitor hypotension, flushing, headache and ankle oedema, which can complicate assessment of volume status.

Short-term additional venodilation and pressure control while captopril addresses the core renin mechanism.

Intravenous glyceryl trinitrate

For pulmonary oedema or severe hypertension in monitored care, start a hospital infusion commonly at 5–10 micrograms/min and titrate to clinical and pressure response under the critical-care protocol.

Continuous pressure monitoring is required; avoid with recent PDE5 inhibitor use, hypotension or right-ventricular preload dependence and watch headache and methemoglobinaemia at high exposure.

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

Kidney failure

Severe ischaemic and microvascular injury may require temporary or permanent dialysis, with uncertain recovery extending beyond the initial hospital admission.

Hypertensive organ injury

Encephalopathy, seizure, retinopathy, myocardial injury, arrhythmia and pulmonary oedema can evolve while pressure and volume are uncontrolled.

Microangiopathic organ damage

MAHA, thrombocytopenia and small-vessel injury can extend beyond kidneys and create diagnostic overlap with other life-threatening TMAs.

Treatment-related hypotension

Over-rapid or excessive pressure reduction can worsen renal and cerebral perfusion, while stopping ACE inhibition prematurely allows renin-driven injury to continue.

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

During acute titration record pressure at least hourly or as physiology requires, with neurological, cardiac, retinal, fluid and urine-output assessment.
Repeat creatinine, potassium, bicarbonate, platelets and haemolysis markers frequently until pressure, TMA and kidney trajectory stabilise.
If dialysis begins, continue scheduled recovery assessment and ACE inhibitor tolerance because urine and filtration may return after prolonged support.
After discharge review home pressure logs, adherence, potassium, creatinine, heart failure and digital perfusion, with a same-day route for recurrent rise.
Audit glucocorticoid and vasoconstrictor exposure and communicate renal-crisis history across primary care, pharmacy, emergency and specialist records.
Reassess pregnancy intentions and contraception because ACE inhibition cannot continue safely through pregnancy.

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

Baseline pressure matters

A patient accustomed to 90/60 mmHg may have clinically serious renal-crisis hypertension at a value others consider normal.

Creatinine rise is expected

Renal function may worsen before vascular recovery, and stopping captopril for this finding alone removes the only treatment with clear survival benefit.

Dialysis is not final

Kidney recovery may occur many months after crisis, so ACE inhibition and longitudinal reassessment continue during replacement therapy.

MAHA does not equal TTP

Renal crisis itself causes microangiopathy, but profound thrombocytopenia or neurological disease still requires urgent ADAMTS13-directed evaluation.

Prophylaxis is not prevention

ACE inhibitor before crisis does not reliably prevent it and can alter the blood-pressure signal used for early recognition.

11Common pitfallsFrequent interpretation and management errors.

01
Dismissing a clinically important pressure rise because it remains below a population hypertension threshold.
02
Waiting for renin, antibody or biopsy results before starting captopril in a typical presentation.
03
Stopping ACE inhibition because creatinine rises during the first days of treatment.
04
Treating pressure with a calcium-channel blocker alone and omitting the renin-pathway treatment.
05
Assuming every MAHA in systemic sclerosis is renal crisis and failing to send urgent ADAMTS13 when TTP is credible.
06
Starting prophylactic ACE inhibition solely because anti-RNA-polymerase-III is positive.