Everyone feels tired sometimes. But when exhaustion lingers for weeks despite decent sleep, it's worth asking whether something measurable is behind it. Persistent tiredness is one of the most common reasons people see a doctor — and a well-chosen blood panel is often the quickest way to find the cause.
The usual suspects behind constant tiredness
Most fatigue that has a medical cause traces back to a handful of areas, and each has a blood marker that checks it:
- Low iron / anaemia — one of the most common causes, especially in women. Checked with a full blood count and ferritin (your iron stores).
- Thyroid problems — an underactive thyroid slows everything down. Checked with TSH and free T4.
- Vitamin B12 and folate deficiency — important for energy and healthy red blood cells.
- Vitamin D deficiency — very common in the UK and linked to tiredness and low mood.
- Diabetes or high blood sugar — checked with HbA1c.
- Underlying inflammation or infection — flagged by CRP and ESR.
- Coeliac disease — an often-missed cause, screened with coeliac antibodies.
Why a panel beats a single test
Because so many things can cause fatigue, testing one marker at a time often means going back for more bloods when the first comes back normal. A dedicated fatigue panel checks blood count, iron, thyroid, key vitamins, blood sugar and inflammation together — giving you and your doctor the full picture from one appointment.
Find the cause of your fatigue
Our "Why Tired" screen checks blood count, iron, B12, folate, vitamin D, thyroid, blood sugar, inflammation and coeliac markers — the common causes of tiredness in one comprehensive panel.
Book a fatigue panelWhat if my results are normal?
Normal bloods are genuinely useful — they rule out the common medical causes and point attention towards sleep, stress, mood, diet and lifestyle, which drive a great deal of everyday tiredness. If symptoms persist despite normal results, your doctor can consider less common causes.
When to get checked
If you've been unusually tired for more than two to three weeks, are struggling to function, or have other symptoms such as breathlessness, weight change or low mood, it's worth testing rather than pushing through. Knowing the cause is the first step to fixing it.
Test for the causes of tiredness
Book online with OneMedicine — CQC-registered clinic in Birmingham, or a home visit / local clinic nationwide. Doctor-reviewed results, most within 24 hours.
Book now
Specialist interest: Cardiovascular Medicine · OneMedicine, CQC-registered clinic