Archive · 8 Sep 2026
Persistent Fatigue, Fever or Bruising May Need Blood Tests
Feeling tired, having a fever or getting a bruise is usually not a sign of cancer.
These symptoms can happen for many ordinary reasons, such as infections, stress or small injuries.
But they should be checked if they keep returning, get worse or happen together.
Some blood diseases can affect the cells made in the bone marrow.
This can cause tiredness, infections, fever, bruising or bleeding.
A simple blood count can check red blood cells, white blood cells and platelets.
Doctors may order more tests if the results or symptoms are concerning.
A blood test cannot find every type of blood cancer, so some people may need scans or tissue tests.
The goal is to investigate persistent symptoms without becoming alarmed by every minor symptom.
Persistent, recurrent or unexplained fatigue, fever and bruising may warrant medical evaluation.
Blood cancers can sometimes begin with ordinary symptoms, although benign causes are more common.
A complete blood count checks haemoglobin, white blood cells and platelets for abnormalities.
Further testing may include a blood smear, imaging, specialised tests or bone marrow examination.
A blood test cannot detect every blood cancer, and some lymphomas may have a normal CBC.
- Who
- People with persistent, recurrent, unexplained or worsening fatigue, fever, bruising or related symptoms.
- What
- Medical guidance on when common symptoms may warrant a blood test and further evaluation for blood or bone-marrow disorders.
- When
- When symptoms persist, recur, lack an obvious explanation, worsen or occur together with other concerning symptoms.
- Where
- The article does not specify a location for the medical guidance.
- Why
- To identify possible abnormalities in blood cells or bone marrow and help rule out serious disease.
- Initial test
- A complete blood count measures haemoglobin, white blood cells and platelets.
- Additional test
- A peripheral blood smear may add diagnostic information when blood abnormalities are suspected.
- Possible symptoms
- Unexplained weight loss, night sweats, recurrent infections, swollen lymph nodes, bone pain and abdominal discomfort may also require evaluation.
- Other investigations
- Depending on the findings, doctors may order iron or vitamin studies, organ-function tests, inflammatory markers or infection-related investigations.
- Further evaluation
- Imaging, specialised blood tests or bone marrow examination may be needed if a blood disorder is suspected.
- Important limitation
- Some lymphomas may have a normal complete blood count and require tissue examination, imaging or specialised laboratory tests.
- Medical context
- Fatigue, fever and bruising have many common causes, and most people with these symptoms will not have cancer.