CBC panel components: what each line of a blood count measures
A complete blood count, or CBC, is a panel of lines that count and size the cells in a blood sample: red cells, white cells and platelets. Each line has a name, a result, a unit and a printed range. This guide describes what each line measures and how it is usually reported. It does not say what any value means for a person.
Not medical advice. This guide describes what the parts of a lab report are and how they are recorded. It does not say what any result means for a person, and it does not recommend treatment, supplements or targets.
What a CBC report lists
A CBC is run on an automated analyser that counts and sizes the cells in a small sample of whole blood. The report groups its lines into three families: red cell lines, white cell lines and platelet lines. A CBC with differential adds the white cell types, each as a percentage of white cells, as an absolute count, or as both.
Some lines are measured directly and some are calculated from others. For example, MCH is typically hemoglobin divided by the red cell count. Which lines are derived depends on the analyser, and the report rarely says, so copy any method note that is printed.
Units are the main source of confusion. White cell and platelet counts appear as 10^3/µL, K/µL, x10E3/uL or 10^9/L, which are the same number, or as cells/µL, which is a thousand times larger. European reports print G/L and T/L. The units guide covers these pairs.
Recording a CBC line by line
Five steps.
Find the three families
Group the lines into red cell, white cell and platelet blocks, as the report does, so each value lands under the right heading in your sheet.
Copy the unit with each count
Write the unit beside every count. A white cell count of 6.2 in 10^3/µL and 6200 in cells/µL is the same count.
Separate percentages from absolute counts
In the differential, Neutrophils % and Neutrophils (abs) are two lines. Give them different row names, or one will overwrite the other.
Note which lines are calculated
If the report marks a line as calculated or names a method, copy that note. Do not assume which lines are derived.
Keep the range per line
Copy the printed range for each line. Ranges often differ by sex and age, and some reports print more than one band.
CBC lines and what each measures
Names vary slightly between labs.
| Line | What it measures | Units you may see |
|---|---|---|
| WBC (white blood cells) | The count of white cells per volume of blood | 10^3/µL, K/µL, 10^9/L, G/L |
| RBC (red blood cells) | The count of red cells per volume of blood | 10^6/µL, M/µL, 10^12/L, T/L |
| Hemoglobin | The concentration of the oxygen-carrying protein in whole blood | g/dL, g/L |
| Hematocrit | The fraction of blood volume taken up by red cells | %, L/L |
| MCV | The average volume of one red cell | fL |
| MCH | The average hemoglobin mass in one red cell | pg |
| MCHC | The average hemoglobin concentration inside red cells | g/dL, g/L |
| RDW | The spread in red cell sizes, as a coefficient of variation or a width | %, fL |
| Platelets | The count of platelets per volume of blood | 10^3/µL, 10^9/L, G/L |
| MPV | The average volume of one platelet | fL |
| Differential | Each white cell type (neutrophils, lymphocytes, monocytes, eosinophils, basophils) as a share of white cells and as a count | %, 10^3/µL, 10^9/L |
| Less common lines | Nucleated red cells (NRBC), immature granulocytes (IG) and reticulocytes: counts of those cell types, printed only on some reports | %, 10^3/µL |
What goes wrong
Most come from losing the unit or the line's exact name.
- Overwriting percentages with counts. Lymphocytes in % and Lymphocytes (abs) are different lines. A shared row name keeps only one of them.
- Reading cells/µL as 10^3/µL. A count of 6200 cells/µL is 6.2 in 10^3/µL. Without the unit the two look a thousand times apart.
- Mixing % and L/L. A hematocrit of 42 % and one of 0.42 L/L are the same fraction. A column holding both has two scales.
- Merging automated and manual differentials. Some reports print an automated differential and, after a smear review, a manual one. Keep the method wording as printed.
- Treating a calculated line as measured. MCH and MCHC are often derived from other lines. Copy the report's note instead of assuming.
- Skipping the sex or age band. If the report prints separate ranges for men and women, record which band was printed for the sample, or keep the text.
How BioPanel helps
BioPanel recognises the CBC lines by name, whichever way the lab spells them: WBC, RBC, Hemoglobin, Hematocrit, MCV, MCH, MCHC, RDW, Platelets, MPV and each differential cell type, with percentage and absolute counts kept as separate rows. A lab report PDF or photo comes back as one row per line, with the printed name kept beside the standard name. In a merged series it converts count units only where the relation is exact. Free: 1 file per day, up to 10 pages, no account. Files over 10 pages are converted up to page 10 on the free allowance; a page code converts the whole file, up to 150 pages. See pricing.
Questions people ask
What does a CBC measure?
It counts and sizes the cells in a blood sample: red cells, white cells and platelets. Further lines describe the average size and hemoglobin content of the red cells.
What is the difference between a CBC and a CBC with differential?
A CBC with differential adds the white cell types, each as a percentage of white cells, an absolute count, or both. A plain CBC stops at the total white cell count.
Are all CBC lines measured directly?
No. Some are calculated from others, for example MCH from hemoglobin and the red cell count. Which lines are derived depends on the analyser, so copy any method note that is printed.
Why are there both percentages and absolute counts?
A percentage gives each white cell type as a share of all white cells. An absolute count gives the number per volume of blood. They are separate lines with separate units, so record both under different names.
Why do count units differ between reports?
Labs print counts as 10^3/µL, K/µL, 10^9/L or cells/µL. The first three are the same number, and cells/µL is a thousand times larger. Always record the printed unit.
Does the CBC tell me what my results mean?
No. This guide describes what each line measures. What a value means for you is a question for a clinician who knows your history. This is not medical advice.