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Have you ever been handed your blood test results only to be left wondering what all the numbers actually mean?
Those red high lighted numbers indicate an abnormality, but you have sickle cell so thats to be expected.
You might never have completely normal results. But how can you tell the difference between abnormalities that are normal and safe for you
and
abnormalities that you should actually be concerned about?
That’s what I want to run through today.
Starting with the most commonly ordered blood test in sickle cell, the Full Blood Count.
The Full Blood Count looks complicated at first glance, but once you understand the key parts, it's easy. You can track your health, spot early warning signs, and understand how to adjust your lifestyle to avoid illness.
Let’s walk through the main sections together.
*Note I've not included numbers or ranges because each lab uses different units of measurement. Understanding the reason for higher or lower than normal levels is the most valuable thing for you.
This tells you how much oxygen-carrying protein is in your red blood cells.
It’s naturally low in sickle cell because the cells break down quickly.
What matters most is your personal baseline. If your Hb suddenly drops well below your usual level, that’s when you should pay attention.
This shows the percentage of your blood made up of red cells.
It tends to mirror the haemoglobin. It also rises if you’re dehydrated and usually increases after a transfusion. Think of it as a general “big picture” red cell marker.
This measures how many red cells you actually have.
It’s often low in sickle cell, and that’s normal. A sharp fall can point to increased haemolysis or infection. A sudden rise might simply mean you're dehydrated.
This is one of the most important tests for sickle cell.
Reticulocytes are young red blood cells your bone marrow releases when it’s working hard.
High Retics usually mean your body is compensating for a fast rate of red blood cell breakdown.
Lower Retics usually mean you're not breaking down red cells as quickly. This can happen if your Fetal Hb is higher, your disease is milder, you’re on treatment, or you’ve made changes that reduce crises.
The key is to know your own usual range. Your retic count is most useful when compared to your personal baseline rather than the lab’s 'normal' range.
This tells you the average size of your red cells.
If you’re on hydroxyurea, your MCV will usually rise, which is expected.
A low MCV can point towards iron deficiency or alpha/beta thalassaemia trait. Again, context matters.
People with sickle cell naturally sit slightly higher than average because of ongoing inflammation.
But a very high WBC can be a sign of infection or an evolving crisis.
A very low WBC can happen if you’re on hydroxyurea or fighting certain viruses, even something as simple as a common cold.
These are the two main types of white cells.
Neutrophils rise more with bacterial infections.
Lymphocytes rise with viral infections.
Both can jump during stress, pain, or inflammation.
These help your blood clot.
They’re often high in sickle cell because the spleen doesn’t filter them properly.
A sudden drop is worth checking, especially if you’re unwell.
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Remember the goal is to understand your patterns, spot changes, and feel more confident when reviewing your results.
To help make things even easier you can now download the FBC cheat sheet. This is a simple summary of everything you need to know when reviewing your full blood count in future. Keep it saved on your phone and you're good to go.
