OVERVIEW

What is pulmonary-renal syndrome?

Pulmonary-renal syndrome, also known as pulmonary hemorrhage-glomerulonephritis syndrome or Goodpasture syndrome, is a clinical syndrome caused by immune system disorders, viral infections, drug side effects, chemical poisoning, heavy metal poisoning, etc. In some cases, no clear cause can be identified.

The main manifestations of pulmonary-renal syndrome include lung infections, recurrent hemoptysis, hematuria, proteinuria, and renal insufficiency. The onset is acute and progresses rapidly, often presenting as a severe and life-threatening condition. Treatment includes immunosuppressive therapy, blood purification therapy, anticoagulation and fibrinolytic therapy, anti-infection therapy, etc.

Is pulmonary-renal syndrome common?

Pulmonary-renal syndrome is very rare.

SYMPTOMS

What are the common manifestations of pulmonary-renal syndrome?

The common manifestations of pulmonary-renal syndrome include: lung infection (cough, sputum, chest pain, etc.), fever, shortness of breath, blood in sputum, recurrent hemoptysis, hematuria, proteinuria, etc.

What serious consequences can pulmonary-renal syndrome cause?

Pulmonary-renal syndrome can lead to severe complications such as serious infections, hemorrhagic shock, respiratory failure, and acute renal failure.

Among these, lung infection is the most common complication, which can worsen pulmonary hemorrhage and may also cause respiratory failure, septic shock, multiple organ failure, and suffocation.

Severe hemoptysis or hematuria can result in hemorrhagic shock, presenting as dizziness, fatigue, cold extremities, or even coma.

Severe kidney damage may lead to acute renal failure or uremia, manifesting as nausea, vomiting, oliguria, or anuria, potentially requiring dialysis treatment.

CAUSES

What causes pulmonary-renal syndrome?

Pulmonary-renal syndrome is caused by autoimmune disorders secondary to various complex etiologies, leading to alveolar capillaritis and glomerulonephritis. Simply put, it occurs when the immune system attacks the body's own organs—the lungs and kidneys.

Who is most likely to develop pulmonary-renal syndrome?

Pulmonary-renal syndrome often occurs secondary to autoimmune diseases, such as anti-glomerular basement membrane disease (anti-GBM disease), ANCA-associated vasculitis, systemic lupus erythematosus, IgA nephropathy, systemic sclerosis, antiphospholipid syndrome, thrombotic microangiopathy, cryoglobulinemia, cholesterol crystal embolism, or drug-induced vasculitis.

It may also develop secondary to viral infections (e.g., epidemic hemorrhagic fever), exposure to certain chemicals (e.g., gasoline, hydrocarbons), or heavy metals.

Therefore, pulmonary-renal syndrome is more common in individuals with the aforementioned conditions or exposures.

Is pulmonary-renal syndrome contagious?

No, it is not contagious.

Is pulmonary-renal syndrome hereditary?

Certain genetic abnormalities may be associated with the development of pulmonary-renal syndrome, but there is insufficient evidence to confirm that it is hereditary.

DIAGNOSIS

What tests are needed to diagnose pulmonary-renal syndrome?

Urinalysis, chest CT, and blood tests including: complete blood count, renal function, ANCA, MPO, PR3, antinuclear antibody panel, APL antibodies, complement, C-reactive protein, and erythrocyte sedimentation rate (ESR) are required. In some cases, a kidney biopsy may also be recommended to confirm the cause.

What is the purpose of the tests for pulmonary-renal syndrome?

• Urinalysis: Detects hematuria or proteinuria, common manifestations of pulmonary-renal syndrome.
• Chest CT: Evaluates lung hemorrhage or infection. Diffuse alveolar hemorrhage is typically seen on CT in pulmonary-renal syndrome.
• Complete blood count: Assesses the severity of bleeding and possible secondary infections.
• Renal function tests: Evaluates kidney damage.
• ANCA, MPO, PR3: Identifies the underlying cause and screens for ANCA-associated vasculitis.
• Antinuclear antibody panel: Helps diagnose autoimmune diseases like systemic lupus erythematosus or Sjögren’s syndrome.
• APL antibodies: Screens for antiphospholipid syndrome.
• Complement, C-reactive protein, ESR: Measures disease activity and monitors treatment response.
• Kidney biopsy: Provides pathological confirmation for targeted treatment.

What precautions should be taken for a kidney biopsy in pulmonary-renal syndrome?

Before a kidney biopsy, the patient’s condition must be thoroughly evaluated. The procedure is contraindicated in cases of severe bleeding tendency, unstable vital signs, or a solitary kidney.

Which diseases are easily confused with pulmonary-renal syndrome? How to differentiate them?

Pulmonary-renal syndrome is often mistaken for pulmonary infection due to its insidious onset and respiratory symptoms, which may overlap with secondary lung infections.

If a patient presents with both renal dysfunction and diffuse alveolar hemorrhage, pulmonary-renal syndrome should be considered rather than a simple lung infection.

Additionally, it must be distinguished from primary kidney disease with coexisting lung disease, which is relatively easier to differentiate. If kidney and lung diseases develop asynchronously and immunosuppressants (e.g., steroids) show poor efficacy for lung symptoms, pulmonary-renal syndrome is unlikely.

TREATMENT

Which department should I visit for pulmonary-renal syndrome?

It is recommended to consult the nephrology or respiratory medicine department.

How is pulmonary-renal syndrome treated?

Pulmonary-renal syndrome requires aggressive treatment, which typically includes:

• Immunosuppressive therapy: Commonly involves a combination of glucocorticoids and immunosuppressants (e.g., cyclophosphamide). If the condition improves, maintenance therapy with glucocorticoids and immunosuppressants continues for a period.
• Plasma exchange/immunoadsorption therapy: Removes pathogenic factors from the plasma, such as antibodies, autoimmune complexes, and inflammatory cytokines. If kidney failure persists after treatment, long-term hemodialysis may be necessary.
• Symptomatic treatment: Pulmonary-renal syndrome often involves complications like lung infections, hemoptysis, and coagulation disorders, requiring concurrent treatments such as anti-infection, hemostasis, anticoagulation, and fibrinolysis.

How is plasma exchange/immunoadsorption therapy performed for pulmonary-renal syndrome? What are its effects?

Plasma exchange involves drawing the patient's blood, separating the plasma containing harmful components via an external device, and reinfusing the remaining blood along with a plasma substitute to eliminate pathogenic factors.

Immunoadsorption involves drawing the patient's blood, removing toxins through an external adsorption device, and then reinfusing the purified blood.

Both blood purification methods effectively remove pathogenic factors from circulation, such as antibodies, autoimmune complexes, and inflammatory cytokines.

What are the common side effects of medications for pulmonary-renal syndrome?

Common side effects of frequently used medications include:

• Glucocorticoids: May cause infections, osteoporosis, gastrointestinal ulcers, central obesity, hypokalemia, diabetes, pancreatitis, and poor wound healing.
• Cyclophosphamide: May cause bone marrow suppression, hair loss, nausea, vomiting, hemorrhagic cystitis, and cardiac damage.
• Rituximab (Rituxan): May cause infections, neutropenia, and angioedema.
• Methotrexate: May cause nausea, vomiting, leukopenia, liver dysfunction, and dermatitis.

Can pulmonary-renal syndrome be cured?

It can be treated effectively.

However, pulmonary-renal syndrome often results from underlying autoimmune diseases. Treating the syndrome does not mean curing the autoimmune condition, which is typically managed rather than eradicated.

Will there be sequelae after treatment for pulmonary-renal syndrome?

Some patients may still experience impaired kidney function despite aggressive treatment, leading to elevated creatinine, hematuria, proteinuria, oliguria, anuria, edema, or even long-term dialysis.

Does pulmonary-renal syndrome require follow-up? How?

Yes, follow-up is necessary.

Regular monitoring includes blood tests (e.g., complete blood count, kidney function, ESR, CRP, complement levels) and disease-specific markers (e.g., ANCA for vasculitis, anti-GBM antibodies for anti-GBM disease, ANA for lupus).

Adjustments to glucocorticoid and immunosuppressant dosages may be needed based on test results.

Is pulmonary-renal syndrome prone to relapse?

Since it often stems from autoimmune diseases, relapse is possible if the underlying condition is not well-controlled.

DIET & LIFESTYLE

What should patients with pulmonary-renal syndrome pay attention to in their diet?

If accompanied by proteinuria or hypoalbuminemia, a high-quality protein diet is recommended.

If symptoms such as gastrointestinal bleeding occur, avoid consuming animal offal, blood products, etc., to prevent interference with stool test results. In the absence of such special conditions, no particular dietary restrictions are necessary.

What should patients with pulmonary-renal syndrome pay attention to in daily life?

Due to the underlying disease and long-term use of glucocorticoids and immunosuppressants, patients often have weaker constitutions and compromised immunity. Therefore, they should:

• Engage in moderate exercise when the condition is controlled, symptoms are relieved, and physical functions are stable. Aim for about 30 minutes of daily activity, combining aerobic and endurance exercises at a moderate intensity without overexertion;
• Ensure proper ventilation in living spaces, avoid crowded places, and wear masks when going out;
• Get sufficient sleep daily;
• Practice self-regulation when experiencing high stress or emotional tension;
• Seek medical attention promptly if symptoms like fever, cough, or phlegm occur.

Does pulmonary-renal syndrome affect fertility?

Patients with pulmonary-renal syndrome face significant challenges in fertility.

Pulmonary-renal syndrome itself is an extremely severe condition, with treatment primarily focused on saving lives. If pregnancy occurs simultaneously, an obstetrician must thoroughly assess the situation and recommend early delivery or termination.

Even after symptom relief, the underlying disease is usually not fully cured, greatly increasing fertility risks. Additionally, medications like glucocorticoids and immunosuppressants can negatively impact fertility.

Most notably, cyclophosphamide is contraindicated during pregnancy, making conception unsuitable during its use.

If pregnancy is strongly desired, it must be pursued under strict supervision by a specialist.

Can patients with pulmonary-renal syndrome exercise?

After treatment and symptom relief, moderate exercise is possible. Combine aerobic and endurance activities, gradually increasing intensity based on individual tolerance.

PREVENTION

Can pulmonary-renal syndrome be prevented?

The exact mechanism of pulmonary-renal syndrome is not yet fully understood, making it difficult to prevent. However, undergoing routine annual check-ups and seeking prompt medical attention if symptoms arise can lead to early detection. Active treatment during the initial stages of primary diseases may help prevent the onset of pulmonary-renal syndrome to some extent.

How to prevent recurrence of pulmonary-renal syndrome?

After symptom relief, long-term oral glucocorticoids and immunosuppressants must be continued. Follow medical advice for gradual dosage reduction—do not reduce or stop medication without guidance, as this can easily lead to recurrence.

How can pulmonary-renal syndrome patients prevent severe complications?

Seek immediate medical attention if symptoms like hemoptysis, hematuria, oliguria, or anuria occur. Strictly adhere to prescribed medications at full doses, and consider plasma exchange if conditions permit.