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Full Blood Count & CRP

Understanding what’s happening inside your body is like unlocking the secrets of a mysterious labyrinth. Two such vital tools that provide insights into your health are the Full Blood Count (FBC) and C-Reactive Protein (CRP) tests. But what exactly are these tests, and why are they crucial? Let's delve into the nitty-gritty of it all!

The Essentials of a Full Blood Count (FBC)

What is a Full Blood Count?

Red Blood Cells (RBC):

  • Normal Function: RBCs are responsible for carrying oxygen from your lungs to the rest of your body.
  • Conditions Checked: Anemia, polycythemia (high RBC count), and dehydration.

Hemoglobin (Hb):

  • Normal Function: Hemoglobin is a protein inside the RBCs that carries oxygen.
  • Conditions Checked: Anemia, polycythemia, and chronic diseases.

Hematocrit (Hct):

  • Normal Function: Hematocrit measures the proportion of blood volume that is occupied by RBCs.
  • Conditions Checked: Dehydration, anemia, and polycythemia.

White Blood Cells (WBC):

  • Normal Function: WBCs are part of the immune system and help your body fight off infections.
  • Conditions Checked: Infections, leukemias, immune disorders, and inflammatory diseases.


  • Normal Function: Platelets help with blood clotting to prevent excessive bleeding.
  • Conditions Checked: Bleeding disorders, thrombocytopenia (low platelet count), and thrombocytosis (high platelet count).

Mean Corpuscular Volume (MCV):

  • Normal Function: MCV is a measurement of the average size of your RBCs.
  • Conditions Checked: Anemia (either due to iron deficiency or due to vitamin B12 or folic acid deficiency).

Mean Corpuscular Hemoglobin (MCH):

  • Normal Function: MCH is the average amount of hemoglobin in the average red cell.
  • Conditions Checked: Anemia, hyperchromia (high MCH levels), and hypochromia (low MCH levels).

Mean Corpuscular Hemoglobin Concentration (MCHC):

  • Normal Function: MCHC measures the average concentration of hemoglobin in your red blood cells.
  • Conditions Checked: Anemia and hemoglobinopathies (disorders affecting the structure, function, or production of hemoglobin).

These components collectively help in diagnosing, monitoring, and managing numerous health conditions.

Understanding CRP (C-reactive Protein)

What is CRP?

C-reactive protein (CRP) is a substance produced by the liver in response to inflammation. Think of it as an alarm system going off when there’s trouble in the body.

The Role of CRP in the Body

CRP plays a key role in your body’s immune response, helping to clear out damaged cells and promote healing. It’s like the cleanup crew that jumps into action after a storm hits.

CRP Test: What Does It Indicate?

CRP and Inflammation

A CRP test measures the amount of this protein in your blood. High levels of CRP can indicate inflammation or infection somewhere in your body.

High-Sensitivity CRP (hs-CRP)

hs-CRP is a more sensitive version of the CRP test and can help evaluate the risk of developing heart disease. Imagine having a super-sensitive burglar alarm that goes off at the slightest hint of trouble, that’s hs-CRP for you!

Correlation Between FBC and CRP

Both FBC and CRP provide invaluable data about your health. While FBC gives a detailed view of the components of your blood, CRP acts as an inflammation marker. Together, they paint a comprehensive picture of your well-being.

Clinical Implications of FBC & CRP


Elevated WBC count and high CRP levels often signal an infection. It’s like smoke signaling a potential fire.


Inflammatory conditions, such as rheumatoid arthritis or lupus, can cause a rise in both the CRP level and certain types of WBCs.


Certain cancers may result in abnormal FBC and elevated CRP levels, helping in early detection or monitoring treatment response.

The Process of FBC & CRP Test


Mostly, no special preparation is required for these tests. It’s as simple as showing up and rolling up your sleeve.


A healthcare provider will draw blood from a vein in your arm. Quick, easy, and relatively painless, these tests can offer a wealth of information about your health.

Interpreting the Results

Normal Range

Just as there’s a speed limit on roads, there’s a ‘normal’ range for FBC and CRP levels. Values outside this range could signify potential health issues.

Out-of-Range Results

However, out-of-range results don’t always signal a problem. They’re like clues in a puzzle, guiding your healthcare provider to understand what’s happening inside your body.

Limitations and Considerations

Although FBC and CRP are insightful, they’re not definitive tests. They can signal that something is wrong but often need to be combined with other tests and clinical information for an accurate diagnosis.


In the vast world of medical testing, the Full Blood Count (FBC) and C-Reactive Protein (CRP) tests stand out as two fundamental pillars. They provide vital information about your general health, help identify numerous conditions, and monitor treatment effectiveness. However, always remember that these tests are part of a bigger picture and should be interpreted in the light of the clinical context and other diagnostic procedures.

High white cell count in your Full Blood Count, particularly with elevated neutrophils, is like your body sounding a high alert. It typically means that your body is fighting off an infection or dealing with an inflammatory condition. Neutrophils, a type of white blood cell, are the first ones to rush to the site where harmful bacteria or viruses have invaded your body, just like the first firefighters arriving at a blaze!

Raised C-Reactive Protein (CRP) levels are like a flashing red light indicating inflammation in your body. CRP is a substance made by the liver in response to inflammation. When your body has a problem like an infection, inflammation, or cancer, your liver makes more CRP to he

Hemoglobin (Hb) is akin to a fleet of delivery trucks carrying oxygen from your lungs to all body parts. High Hb levels may indicate your body is compensating for low oxygen, possibly from lung disease or living in high altitudes. Low Hb levels can indicate anemia, so your body lacks enough oxygen-carrying trucks. This can make you feel tired or breathless.

Mean Corpuscular Volume (MCV) tells us the average size of your red blood cells – it’s like measuring the average size of apples in an orchard. If your MCV is high, your red blood cells are larger than normal, which can occur due to vitamin B12 or folate deficiency (like growing oversized but fewer apples because of poor fertilization).

If your MCV is low, your red blood cells are smaller than normal, often seen in iron-deficiency anemia (like growing small, undernourished apples due to lack of water). Either way, abnormal MCV levels can hint towards a problem with your red blood cells that needs further investigation.

At Urgent Care Brisbane, our emergency lab machine can test for FBC and CRP within 1-2 hours and is very helpful in the diagnosis of complex cases.

Urgent Care Brisbane is the emergency walk-in clinic you can visit for your emergency health care needs, and trust our team to look after you.

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