Mar 20, 2025
What Your Immune System Wishes You Knew About Your Bloodwork
Getting sick often or battling frequent colds? Your bloodwork could hold the answers.
Written by
Mito Team
When you’re constantly catching colds or just always tired, it’s easy to blame stress or the weather. But your immune system could be waving red flags that are hiding in plain sight—inside your bloodwork.
Many people don’t realize that frequent illness, fatigue, or even slow recovery are signs that your immune system isn’t working its best. The good news? Blood tests help you understand what’s happening beneath the surface and give you clues on how to boost your immune system and feel better long term.
Why You Might Be Getting Sick More Often
Feeling like you’re always one sneeze away from your next cold? It might not just be bad luck. Some of the most common reasons your immunity may be low are poor sleep, vitamin D deficiency, and chronic inflammation.
Each of these can be detected through a lab test that analyzes specific blood markers. These results provide a powerful window into how you can strengthen your immune system.
3 Biomarkers That Matter Most for Immune Health
1. Vitamin D
You probably know vitamin D helps with strong bones. But it’s also a quiet superhero for your immune system.
Low vitamin D levels have been linked to a higher risk of infections, including the common cold and more serious illnesses like pneumonia. That’s because vitamin D helps regulate both your body’s first line of defense and its more targeted response.
A simple blood test checks your vitamin D levels. Ideally, they should be above 30 ng/mL, but many experts recommend aiming for 40 to 60 ng/mL for better immune support. If you're not getting enough sun or eating vitamin D-rich foods, a vitamin D supplement might help.
2. hsCRP
You might not feel it, but chronic, low-level inflammation can wear your immune system down over time. One of the best ways to check for this is through a blood marker called high-sensitivity C-reactive protein, or hsCRP.
hsCRP levels rise when there’s inflammation in your body, even if it’s mild or hidden. Short-term inflammation, like what happens after a cut or workout, is normal. However, long-term inflammation affects your immune system and lessens its effectiveness.
If your hsCRP is above 1.0 mg/L, it may be a sign that your body is dealing with chronic inflammation. This weakens your immunity, slows your healing, and increases your risk for other conditions, like heart disease. Improving your sleep, nutrition, stress levels, and exercise helps lower inflammation.
3. White Blood Cells (WBCs)
WBCs are your immune system’s frontline soldiers. They patrol your bloodstream, looking for harmful bacteria, viruses, and other threats.
A Complete Blood Count (CBC) test measures the number and types of white blood cells in your body.
If your WBC count is too low, it might mean your immune system is weakened or struggling.
If it's too high, it could mean your body is fighting off something, or reacting to stress or inflammation.
Your doctor can use this simple test to get a clearer picture of how well your immune system is working.
How Sleep Ties It All Together
Here’s something surprising: all of these key immune markers—vitamin D, inflammation, and white blood cells—are affected by sleep.
Poor sleep doesn’t just make you groggy. It lowers your immune defenses, raises inflammation, and may even contribute to lower vitamin D levels over time.
In fact, a 2021 review found that sleep loss disrupts immune cell activity. It also increases certain inflammatory signals called cytokines that weaken your immunity. So, aim for 7 to 9 hours of good-quality sleep each night to support your immune system.
So, What Can You Do?
Improving your immune system starts with simple, informed actions:
Check your Vitamin D: Especially if you get sick often or live somewhere with little sun.
Ask about hsCRP: It’s a small test that gives big insights about inflammation.
Get a CBC: Even if you feel fine, it’s a helpful snapshot of your immune system.
Fix your sleep routine: Go to bed at the same time each night and limit screens before bed.
Support your body daily: Eat nutritious food, stay active, manage stress, and stay hydrated.
Your immune system has a story to tell—and your bloodwork is the script. By paying attention to your vitamin D, hsCRP levels, and white blood cell count, you'll have a clue on why you might be getting frequent colds and infections.
At Mito Health, we make it simple to track these important markers with our core blood tests and science-backed insights. Whether you're dealing with fatigue, frequent illness, or just want to stay ahead of the curve, our tools help you take charge of your immune health.