No, B12 is not directly checked in a Complete Blood Count (CBC).
While a CBC is a common blood test that provides information about the different types of cells in your blood, it does not measure the level of Vitamin B12.
Here's why and what tests are done for B12 assessment:
What a CBC Does Measure
A CBC provides information about:
- Red blood cells (RBCs): Number, size, and hemoglobin content.
- White blood cells (WBCs): Number and types.
- Platelets: Number.
These parameters help diagnose conditions like anemia, infections, and bleeding disorders.
How B12 Deficiency is Assessed
According to our reference, to check for B12 deficiency, initial lab tests should include:
- Complete Blood Count (CBC) with a peripheral smear: While the CBC doesn't measure B12 directly, it can provide clues. For example, macrocytic anemia (enlarged red blood cells) can be a sign of B12 deficiency.
- Serum B12 Levels: This is the specific blood test that measures the amount of B12 in your blood.
- Folate Levels: Folate deficiency can also cause similar symptoms and needs to be tested to differentiate between B12 deficiency.
If the diagnosis is still unclear after these tests, other more specialized tests like MMA and homocysteine levels might be used.
Why B12 is not in CBC
B12 is a vitamin, not a blood cell component. CBCs are designed to assess the formed elements of blood (cells), not vitamin levels.
In summary:
| Test | Measures | Includes B12 Measurement? |
|---|---|---|
| CBC | Red blood cells, White blood cells, Platelets | No |
| Serum B12 Level | Amount of Vitamin B12 in the blood | Yes |
| Folate Levels | Amount of Folate in the blood | No |
In conclusion, while a CBC is often part of the workup for suspected B12 deficiency, it is the serum B12 level that specifically tests for vitamin B12. The CBC can offer clues, like macrocytic anemia, but won't directly measure the B12 level.
