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Fatigue is one of the most common symptoms we encounter in healthcare – and also the main reason why thousands of Swedes choose to have a health check at the Test Clinic every year. In many cases, there is a concrete explanation that can be discovered through a simple blood test. Lack of iron, B12 or vitamin D, low metabolism, blood sugar fluctuations or impaired kidney or liver function are common causes that affect energy levels without giving clear symptoms otherwise.
Since fatigue is often due to several interacting factors, a broad health check is the most informative first step. By analyzing blood status, hormone balance, vitamin and mineral levels, blood sugar, blood fats and liver and kidney values, you get a comprehensive picture of the body's energy system – and can detect imbalances early before they lead to illness.
But fatigue is not always about medical causes. Lifestyle, stress, sleep, fluid intake and dietary habits greatly affect how we feel. The blood test therefore becomes a valuable tool for understanding whether the cause is biological, lifestyle-related – or a combination of both.
What to do when fatigue doesn't go away?
It's perfectly normal to feel tired sometimes – after stressful periods, temporary illness, poor sleep or intense exercise. But when fatigue becomes long-lasting, is not relieved by rest and begins to affect everyday life, it is often a sign that the body's energy metabolism or oxygenation is not working properly. Fatigue is then not just a symptom – it is a physiological signal that the body is missing something, is being overloaded or is trying to compensate for an imbalance.
A health check can often explain why. By analysing the blood cells, nutrient levels, hormones and organ markers, you can get a clear picture of what is happening in the body. For example, the tests can show whether oxygen transport via the red blood cells is impaired, whether energy production in the cells is affected by vitamin or iron deficiency, or whether metabolism is disrupted by a disorder in the thyroid gland or adrenal glands.
The blood acts as a mirror of the body's internal environment. A blood test can identify any deficiencies, inflammation or altered kidney and liver function long before clear symptoms occur. In some cases, fatigue is due to something temporary, such as stress or lack of sleep, but in many cases, a simple health check can provide concrete answers and guide you to the right treatment or lifestyle change.
Some of the most common medical causes of your fatigue
Fatigue can have many causes, and sometimes it is the combination of several factors that causes energy levels to drop. Here are some of the most common medical causes that appear in blood tests:
- Anemia: Low hemoglobin or iron deficiency causes the body to receive less oxygen. This leads to fatigue, dizziness and lack of energy.
- Vitamin and mineral deficiencies: A deficiency in vitamin B12, vitamin D or folate can affect both energy, mood and nervous system.
- Thyroid disorders: Low metabolism (hypothyroidism) can cause fatigue, chills and weight gain – but can be detected via blood tests.
- Impaired kidney function: When the kidneys do not filter the blood effectively, waste products can accumulate and contribute to fatigue and weakness.
- Diabetes or blood sugar fluctuations: Irregular blood sugar affects energy levels and can cause fatigue, especially after meals.
- Low-grade inflammation: High levels of CRP or white blood cells may indicate that the body is fighting something that is draining energy.
Lifestyle, stress and lack of sleep also play a role
Not all forms of fatigue are due to illness. Sometimes it is a matter of lifestyle factors – too little sleep, irregular eating habits, stress or being sedentary. Dehydration, alcohol and caffeine can also affect energy levels. But it is only when medical causes have been ruled out that you know for sure that it is lifestyle-related fatigue. That is why a blood test is a good starting point – it gives an objective picture of how the body actually feels.
When should I consider having a health check-up for my fatigue?
If you feel tired for a long time without a clear reason, a blood test is often the best first step. It is quick, easy and can provide clear answers within a couple of days. At Testmottagningen, we often see that people get concrete explanations – and in many cases even solutions – just through a basic health check.
Conditions when you might consider testing yourself for your fatigue:
- Have felt tired for more than a few weeks despite adequate sleep.
- Experience difficulty concentrating, dizziness or headaches.
- Have changes in appetite, weight or mood.
- Suspect a deficiency in iron, B12 or vitamin D.
- Take medication that affects hormones, blood pressure or metabolism.
Blood tests that can give you answers
We must be clear that fatigue is a very non-specific symptom that can be caused by everything from nutritional deficiencies to hormonal disorders or effects on the body's organ function. Therefore, it is often most effective to start with a broader health check instead of testing individual blood samples separately, which is also cost-effective. A comprehensive analysis makes it possible to see how several important systems in the body interact, for example blood count, metabolism, hormone balance, cardiovascular function, vitamin status, blood sugar, liver and kidney function. This provides a more complete medical picture of what may actually be behind your fatigue.
We have developed several health checks that include these areas, adapted to gender and medical needs. All health checks are supplemented with a doctor's report:
- Health Check Woman – analyzes, among other things, blood status, thyroid tests, vitamin and mineral levels, blood sugar, and liver and kidney values.
- Health Check Man – contains corresponding analyses, with the addition of markers linked to male hormone balance and metabolism.
A general health check is usually the most informative first step in the case of prolonged fatigue, as it provides an overall picture of several important body functions at once. The analysis includes, among other things, blood status, which shows whether you have signs of anemia, infection or inflammation – factors that affect oxygenation and thus energy. At the same time, the levels of vitamins and minerals, such as iron, folate, B12 and vitamin D, which are necessary for the cells' energy production and the functioning of the nervous system, are checked.
Thyroid hormones (TSH, T4 and T3) are also analyzed, since a low metabolism is one of the most common causes of long-term fatigue and feeling cold, especially in women. Blood sugar and the long-term HbA1c value are included to show how the body regulates the absorption of energy from food - sometimes fluctuating blood sugar levels or incipient insulin resistance, especially after meals, can be behind the fatigue.
In addition, liver and kidney markers are examined, which reveal how effectively the body cleanses the blood and handles metabolic waste products. Similarly, analyses of blood fats - cholesterol, LDL, HDL and triglycerides - can provide important information about the health of the cardiovascular system. Elevated blood lipids or low-grade inflammation in the vascular wall can affect circulation and contribute to oxygen deficiency in the tissues, which sometimes manifests as decreased energy, headaches or general fatigue.
Together, these analyses provide a clear picture of how the body produces, transports and uses energy. It is often only when you see the whole picture – how blood, hormones, nutrients and organ function interact – that the cause of fatigue becomes clear. A more comprehensive health check-up therefore not only provides answers, but also the opportunity to prevent and correct imbalances early on before they lead to larger problems.
Remember that fatigue can often be influenced – even with small lifestyle changes
Fatigue does not always have to be a sign of illness. It is often the body's way of telling you that it is out of balance – perhaps important nutrients are missing, recovery is insufficient, or energy levels are affected by stress, lack of sleep or irregular habits. Lifestyle factors such as diet, physical activity, fluid intake and alcohol or caffeine habits are of great importance for how the body can cope with the demands of everyday life.
A blood test can provide valuable guidance in this work. By seeing how nutritional status, hormones and organ function interact, you get a concrete picture of your health – and can more easily understand which changes actually make a difference. In many cases, adjustments to diet, sleep or stress level are enough to regain energy, especially if any deficiencies are discovered and addressed in time.
Through the Test Clinic, we have seen how thousands of people have gained clarity and insight into their health thanks to a health check. For many, the solution is about small but important changes – an adjusted diet, the right supplements, better sleep or optimized medication – which together can make a big difference to how you feel in everyday life. For others, knowing that there are no deviations can also contribute to increased energy and peace of mind.
We are happy to help you if you want to find out what is behind your fatigue
If you feel tired for no apparent reason, a blood test can be the easiest and most reliable way to understand what your body is trying to tell you. You do not need a referral, and you always receive a medical assessment by a doctor who explains what your values mean when you order a health check with us.
Understanding the cause of your fatigue is the first step towards regaining your energy. A health check can give you just that knowledge - and an opportunity to feel better.
