Symptoms & complaints
Fatigue and your blood
Persistent fatigue often has several causes. Blood testing can reveal a number of common, treatable causes. Below you read which blood values are relevant.
Common causes you can measure
Iron deficiency (low ferritin), a lack of vitamin D or vitamin B12, and an underactive thyroid (TSH/Free T4) are among the most common measurable causes of fatigue. An abnormal value does not always explain the symptom, and a normal value does not rule everything out. Always discuss the result with a doctor.
When testing is useful
For fatigue lasting more than a few weeks, without a clear explanation, targeted blood testing can provide direction. It does not replace a visit to the GP for alarm symptoms such as unintended weight loss or shortness of breath.
Relevant blood values
Frequently asked questions
Which blood values relate to fatigue?
Often relevant are iron/ferritin, vitamin D, vitamin B12 and thyroid function (TSH, Free T4). Which ones are useful for you depends on your situation.
Does blood testing solve my fatigue?
Blood testing reveals possible, treatable causes. It is a tool; you discuss the result with a doctor for the right next steps.
Do I need to fast?
For these markers fasting is usually not needed. If in doubt or combined with glucose we advise fasting; see our guide on fasting.
Sources
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