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Leukemia
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Blood Heart Circulation

Leukemia

Leukemia is a cancer of the blood-forming tissues that causes the bone marrow to produce large numbers of abnormal white blood cells.

What is leukemia?

Leukemia is a term for cancers of the blood cells. Leukemia starts in blood-forming tissues such as the bone marrow. Your bone marrow makes the cells which will develop into white blood cells, red blood cells, and platelets. Each type of cell has a different job:

  • White blood cells help your body fight infection
  • Red blood cells deliver oxygen from your lungs to your tissues and organs
  • Platelets help form clots to stop bleeding

When you have leukemia, your bone marrow makes large numbers of abnormal cells. This problem most often happens with white blood cells. These abnormal cells build up in your bone marrow and blood, crowding out the healthy blood cells and making it hard for your cells and blood to do their work.

What are the types of leukemia?

There are different types of leukemia, categorized by the type of blood cell that becomes cancerous and whether the disease grows quickly or slowly.

The type of blood cell involved could be:

  • Lymphocytes: A type of white blood cell.
  • Myeloid cells: Immature cells that become white blood cells, red blood cells, or platelets.

The growth rate is categorized as:

  • Acute leukemia: Fast-growing; it usually gets worse quickly if not treated.
  • Chronic leukemia: Slow-growing; it usually gets worse over a longer period of time.

The main types of leukemia are:

  • Acute lymphocytic leukemia (ALL): The most common type of cancer in children, though it can also affect adults.
  • Acute myeloid leukemia (AML): More common in older adults but can also affect children.
  • Chronic lymphocytic leukemia (CLL): One of the most common types of leukemia in adults, often occurring during or after middle age.
  • Chronic myeloid leukemia (CML): Usually occurs in adults during or after middle age.

What causes leukemia?

Leukemia happens when there are changes in the genetic material (DNA) in bone marrow cells. The cause of these genetic changes is unknown.

Who is at risk for leukemia?

While risk factors vary by specific type, overall risk increases with age. Leukemia is most common in individuals over age 60.

What are the symptoms of leukemia?

Some of the symptoms of leukemia may include:

  • Feeling tired
  • Fever or night sweats
  • Easy bruising or bleeding
  • Weight loss or loss of appetite
  • Petechiae: Tiny red dots under the skin caused by bleeding.

Other symptoms can vary by type, and chronic leukemia may not cause symptoms at first.

How is leukemia diagnosed?

Your health care provider may use several tools to diagnose leukemia:

  • A physical exam
  • A medical history
  • Blood tests, such as a complete blood count (CBC)
  • Bone marrow tests, including bone marrow aspiration and bone marrow biopsy, which involve removing a sample of bone marrow and bone for lab analysis.
  • Genetic tests to look for gene and chromosome changes

Once a diagnosis is made, additional tests—such as imaging tests or a lumbar puncture to collect cerebrospinal fluid (CSF)—may be used to see if the cancer has spread.

What are the treatments for leukemia?

Treatments depend on the type and severity of the leukemia, your age, your overall health, and other factors. Possible treatments include:

  • Chemotherapy
  • Radiation therapy
  • Chemotherapy with stem cell transplant
  • Targeted therapy: Drugs or other substances that attack specific cancer cells with less harm to normal cells.

Frequently Asked Questions

Common early warning signs include persistent fatigue, unexplained bruising or bleeding (such as nosebleeds or gum bleeding), frequent infections, unexplained weight loss, night sweats, bone or joint pain, and swollen lymph nodes. If you notice several of these symptoms lasting more than a few weeks, schedule a visit with your primary care provider for further evaluation.
cute leukemias (ALL, AML) usually require intensive chemotherapy to achieve remission quickly, often followed by targeted therapy, stem‑cell transplant, or clinical‑trial drugs. Side effects can include severe nausea, hair loss, low blood counts leading to infection or bleeding, and organ toxicity. Chronic leukemias (CML, CLL) often start with watchful waiting or oral targeted agents (e.g., tyrosine‑kinase inhibitors for CML) that control disease more slowly and have milder side effects such as mild diarrhea, muscle cramps, or liver‑function changes. Treatment choice depends on disease subtype, genetic findings, patient age, and overall health.
Diagnosis typically starts with a complete blood count (CBC) that shows abnormal white blood cell, red blood cell, or platelet levels. If results are suspicious, a bone‑marrow aspiration/biopsy is performed to examine the cells directly. Additional tests may include flow cytometry, cytogenetic analysis, and molecular studies to identify specific genetic mutations. You’ll be asked to fast for a few hours before a bone‑marrow procedure and to arrange someone to drive you home afterward because of sedation.
Practice strict hand hygiene, avoid crowds during peak infection seasons, and keep up‑to‑date with vaccinations (influenza, pneumococcal) after discussing timing with your oncologist. Use a soft toothbrush, avoid flossing if platelet counts are low, and steer clear of activities that could cause cuts. Your care team may prescribe prophylactic antibiotics, antifungals, or growth‑factor injections to boost white‑cell counts, and they will monitor platelet levels regularly to determine if transfusions are needed.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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