If you have been tired for weeks or months with no obvious explanation, a blood test is the most cost-effective starting point. There is a fairly short list of common biomarker causes of unexplained fatigue, and most can be addressed once identified.
Six common biomarker causes
Low iron (ferritin). Underactive thyroid (TSH, free T4, free T3). Vitamin D deficiency (particularly October to April in the UK). Vitamin B12 or folate deficiency. Anaemia from any cause (full blood count). Insulin resistance and blood sugar dysregulation.
What testing looks like
A combined fatigue panel covers all of the above in a single blood draw. Results show where each marker sits relative to the typical reference range. Anything out of range gets flagged for follow up with a healthcare professional.
What blood tests will not catch
Sleep disorders (sleep apnoea, insomnia). Mental health conditions including depression and anxiety. Chronic fatigue syndrome / ME. Long COVID in its later stages. Lifestyle factors (overwork, poor sleep hygiene). A normal blood test does not rule these out, it just helps narrow the possibilities.
Practical next step
If a fatigue panel comes back clean and you are still tired, see your GP. There are causes that need clinical assessment beyond what biomarkers can show. Chxhealth is a biomarker and genetic data provider. We do not diagnose, treat or prescribe. Our service supports your wellbeing journey alongside your healthcare professional.
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Frequently asked questions
How long should I have been tired before testing?
Two to four weeks of persistent unexplained fatigue is a sensible threshold. Brief tiredness usually reflects sleep, illness recovery or stress.
Will the test diagnose what is wrong with me?
No. Chxhealth is a biomarker and genetic data provider. We do not diagnose, treat or prescribe. Our service supports your wellbeing journey alongside your healthcare professional. The test surfaces markers that contribute to fatigue. Any out-of-range result is a conversation for your GP.
About this article. Educational content. Chxhealth is a biomarker and genetic data provider. We do not diagnose, treat or prescribe. Our service supports your wellbeing journey alongside your healthcare professional. For medical advice about your health or results, please speak to a qualified clinician.