Quick answer
A CBC measures three groups of blood cells: red blood cells, white blood cells, and platelets. It also reports a few extra numbers calculated from those groups. A CBC can point to anemia, infection, inflammation, or immune problems. It can also flag dehydration, clotting issues, and some blood cancers. Every number on the report has meaning, even when it falls "in range."
The three cell groups
Red blood cells (RBCs)
These carry oxygen from your lungs to the rest of your body. A low count causes tiredness and shortness of breath. A high count can point to dehydration, smoking, or a rarer condition.
White blood cells (WBCs)
These are your immune system's defense force. The total count, and the mix of different types, shows whether you are fighting an infection, dealing with an allergy, or carrying ongoing inflammation.
Platelets
These are your clotting cells. A low count means you may bruise or bleed more easily. A high count can point to inflammation, or rarely, something more serious.
The red blood cell numbers
RBC count
This counts your red blood cells. Men: 4.5 to 5.9 million per microliter. Women: 4.1 to 5.1 million. A low count often means anemia or blood loss. A high count can mean too many red blood cells. It can also mean smoking, dehydration, or living at high altitude.
Hemoglobin (Hb)
This protein inside red blood cells carries oxygen. Men: 13.5 to 17.5 g/dL. Women: 12.0 to 15.5 g/dL. The healthy target is above 14 for men and above 13 for women. Low hemoglobin is what actually defines anemia. This holds true no matter what your RBC count shows.
Hematocrit (Hct)
This is the share of your blood made up of red blood cells, shown as a percentage. Men: 41 to 53%. Women: 36 to 46%. It tends to move together with hemoglobin. A high hematocrit can point to dehydration. These lab ranges are wide, so it helps to know what an optimal hemoglobin and hematocrit look like.
MCV (average red blood cell size)
MCV is the average size of your red blood cells. The standard range is 80 to 100 fL, a unit of volume. A low MCV, under 80, usually points to iron deficiency. It can sometimes point to an inherited condition called thalassemia. A high MCV, over 100, usually points to low B12 or folate. It can sometimes point to liver problems or alcohol use. This one number narrows down the likely cause of anemia a great deal.
MCH and MCHC
MCH is how much hemoglobin sits inside an average red blood cell. MCHC is how packed that hemoglobin is inside the cell. Both help confirm what the MCV already shows. A low MCH with a low MCV points strongly to low iron. A low MCHC means the cells look pale under the lens.
RDW (red cell size variation)
RDW is how much your red blood cells vary in size. The standard range is 11.5 to 14.5%. A high RDW often shows up early in a nutrient deficiency. Some research also links a high RDW to higher long-term health risk.
The white blood cell numbers
WBC count
This counts your total white blood cells. The standard range is 4,000 to 11,000 per microliter. A low count, under 4,000, can point to a viral infection. It can also point to certain medicines, an autoimmune condition, or a bone marrow issue. A high count, over 11,000, can point to a bacterial infection, inflammation, stress, or steroid use.
The WBC differential
A CBC with a differential breaks your white blood cells into five types. Each type gets a percentage and a raw count.
Type | Standard range | What a high result may suggest |
|---|
Neutrophils | 40 to 70% | Bacterial infection, sudden inflammation, or stress |
Lymphocytes | 20 to 40% | Viral infection, or certain rare cancers |
Monocytes | 2 to 8% | Ongoing inflammation, or recovery from infection |
Eosinophils | 1 to 4% | Allergies, parasites, or asthma |
Basophils | under 1% | Allergic reactions, or a rare blood disorder |
Doctors also calculate a ratio between neutrophils and lymphocytes. This is called the NLR. More doctors now use it as a sign of low-grade inflammation. An NLR above 3, in someone with no symptoms, is worth tracking over time.
The platelet numbers
Platelet count
This counts your platelets. The standard range is 150,000 to 450,000 per microliter. A low count, under 100,000, points to a bleeding tendency. The cause can range from a viral illness like dengue to certain medicines or an autoimmune condition. A high count, over 450,000, can point to ongoing inflammation, low iron, or recent surgery. Rarely, it points to a bone marrow condition.
In the Philippines, platelet count matters a lot during dengue season. A fast drop over just a few days is part of how doctors diagnose it.
MPV (average platelet size)
This measures the average size of your platelets. A high MPV alongside a low platelet count often means your body is replacing platelets faster than usual. Some studies also link a high MPV on its own to heart risk.
Common patterns and what they mean
Pattern 1: Iron deficiency anemia
Low hemoglobin, low hematocrit, and a low MCV. Often paired with a high RDW. This is common in menstruating women and in people who eat mostly plant-based diets. A ferritin under 30 ng/mL confirms it. Some doctors flag anything under 50 as low too.
Pattern 2: Low B12 or folate
Normal or slightly low hemoglobin, with a high MCV. B12 and folate testing confirms this.
Pattern 3: A bacterial infection
A high WBC count, with neutrophils making up most of the increase.
Pattern 4: A viral infection, including dengue
Often a low WBC count. Lymphocytes make up a larger share. Platelets tend to fall too.
Pattern 5: Ongoing low-grade inflammation
A borderline high WBC and neutrophil count, a high NLR, and slightly high platelets.
Pattern 6: Dehydration
High red blood cells, hemoglobin, and hematocrit. This usually corrects once you rehydrate.
When to see a doctor promptly
Reach out to a doctor quickly if you see:
- Hemoglobin under 10 g/dL
- A WBC count under 3,000 or over 15,000 with no clear cause
- A platelet count under 100,000 or over 600,000
- A sudden change of more than 20% from your last CBC
- Any unusual result alongside fever, weight loss, fatigue, easy bruising, or bleeding
How a &you Labs report handles your CBC
A &you Labs report shows every CBC value next to the standard lab range and the healthy target range. A doctor's written interpretation flags anything unusual or worth watching. You always get context for what the numbers mean.
Frequently asked questions
Do I need to fast for a CBC?
No. A CBC can be drawn at any time of day and does not need fasting. Most other tests grouped alongside it do need fasting, so labs often schedule one fasting draw to cover everything at once.
How long do CBC results usually take?
A CBC is one of the simpler tests to process, since it needs no special preparation. It is often one of the faster results to come back within a fuller panel.
Can a CBC detect cancer?
A CBC alone cannot diagnose cancer. But some blood cancers, like leukemia, cause CBC patterns that prompt a doctor to look further. Solid tumors usually do not change a CBC directly. They only do so if they cause anemia or body-wide inflammation.
What does a high MCV mean?
A high MCV means your red blood cells are bigger than usual. The most common causes are low vitamin B12 or low folate. Heavy drinking and some liver problems can raise it too. Your doctor will check B12 and folate next.
What do MCH, MCHC, and RDW mean on a CBC?
MCH is how much hemoglobin sits in an average red blood cell. MCHC is how packed that hemoglobin is. RDW is how much your cells vary in size. Read together with MCV, they point to the cause of anemia.
Why do my CBC numbers change between tests?
Hydration, exercise, time of day, illness, and even stress can shift your numbers. This can happen within the normal range. A pattern across several tests matters more than any single result.
Are CBC reference ranges different for Filipinos?
The standard ranges used worldwide work reasonably well for adult Filipinos. Ranges for children and pregnant women are different, based on age and stage.
Key takeaways
- A CBC measures red blood cells, white blood cells, and platelets, plus extra numbers like MCV and RDW that sharpen the picture.
- The MCV alone narrows down the likely cause of anemia a great deal.
- The WBC differential shows whether your immune system is dealing with bacteria, a virus, an allergy, or ongoing inflammation.
- Platelet trends matter, especially with dengue common in the Philippines.
- A CBC is the cheapest useful test in medicine. Read it carefully, even when nothing gets flagged.
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