Merck Manual

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Diffuse Alveolar Hemorrhage

By

Joyce Lee

, MD, MAS, University of Colorado Denver

Last full review/revision May 2020| Content last modified May 2020
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NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
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Diffuse alveolar hemorrhage is a syndrome of recurrent or persistent bleeding into the lungs, caused most often by an autoimmune disorder.

  • Common symptoms are difficulty breathing and coughing, often coughing up blood.

  • People usually have a chest x-ray, blood tests, and sometimes examination of the breathing passages with a flexible viewing tube (bronchoscopy).

  • Treatment of autoimmune causes involves suppression of the immune system with corticosteroids and often cyclophosphamide (a chemotherapy drug) or rituximab (a type of immune suppression drug).

An important function of the immune system is fighting off infections. To do this, the immune system recognizes microorganisms as foreign to the person and produces proteins (antibodies) that join with the microorganisms so they can be removed from the body. In autoimmune disorders, the body mistakenly reacts against a person's own tissues as if they were foreign. In autoimmune disorders that involve the lungs, the immune system attacks and damages lung tissue. Autoimmune disorders that affect the lungs also often affect other organs, particularly the kidneys.

Diffuse alveolar hemorrhage is a syndrome, not a particular disorder. A syndrome is a group of symptoms and other abnormalities that occur together but may be caused by several different disorders. Diffuse alveolar hemorrhage involves damage to the small blood vessels that supply the lungs, causing blood to accumulate in the tiny air sacs (alveoli) of the lungs. Such blood vessel damage can result from several disorders.

Causes

Many disorders can cause diffuse alveolar hemorrhage.

The most common causes are

Other disorders that can cause diffuse alveolar hemorrhage include

  • Lung infections (for example, hantavirus infection)

  • Toxins (for example, isocyanates, crack cocaine, trimellitic anhydride, and certain pesticides)

  • Drugs (for example, amiodarone, bleomycin, infliximab, methotrexate, montelukast, nitrofurantoin, phenytoin, and propylthiouracil)

  • Heart disorders (for example, mitral stenosis)

  • Defective blood clotting caused by disorders or anticoagulant drugs

  • Transplantation of organs or bone marrow

  • Isolated pauci-immune pulmonary capillaritis (an immune disorder that affects people between ages 18 and 35 and damages the tiny blood vessels of the lungs, causing blood to leak into the lungs but no other problems)

  • Idiopathic pulmonary hemosiderosis (a rare disorder, possibly due to autoimmune injury, that causes only diffuse alveolar hemorrhage and typically affects children younger than 10 years)

Symptoms

Diffuse alveolar hemorrhage syndrome can cause

  • Cough

  • Difficulty breathing

  • Fever

When the disorder is severe, breathing may be extremely difficult. People may gasp and have bluish discoloration of the skin (cyanosis). At least two thirds of all people with diffuse alveolar hemorrhage cough up blood. Some people die.

People may also have other symptoms typical of the disorder that caused the diffuse alveolar hemorrhage.

People who have repeated episodes of bleeding into the lungs can develop anemia (low blood count, often causing fatigue) and lung scarring that causes pulmonary fibrosis.

Diagnosis

  • Chest x-ray

  • Sometimes insertion of a flexible viewing tube into the lungs (bronchoscopy) with fluid wash out (bronchoalveolar lavage)

Doctors can often diagnose diffuse alveolar hemorrhage by a person's symptoms and chest x-ray findings. Chest x-rays typically show abnormal white patches in the lungs caused by lung bleeding. If the diagnosis is not clear based on symptoms and chest x-ray findings (for example, if the person has not coughed up blood), doctors may need to insert a flexible viewing tube into the lungs (bronchoscopy) and wash out the lungs with fluid (bronchoalveolar lavage) to check for small amounts of blood.

The level of red cells in the blood is measured to test for anemia.

After diffuse alveolar hemorrhage has been diagnosed, the cause must be determined. A variety of blood tests may be done, depending on what disorders seem to be likely causes. Urinalysis is done to tell whether the person has kidney damage, characteristic of the pulmonary-renal syndrome.

Treatment

  • Treat specific cause of disorder

  • Sometimes corticosteroids, cyclophosphamide, or rituximab

  • Supportive measures

The disorder causing diffuse alveolar hemorrhage is treated.

Autoimmune disorders are commonly treated with corticosteroids (such as prednisone) and sometimes cyclophosphamide (a chemotherapy drug) or other drugs (such as rituximab) that suppress the immune system.

Problems that people with diffuse alveolar hemorrhage also have, such as difficulty breathing and clotting disorders, are also treated. For example, people may be given oxygen or may need to be on a ventilator for a period of time.

Blood transfusions, plasma exchange, or other measures may also be needed.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version

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