For many people, hormones are a familiar term from biology lessons or visits to the doctor, but what exactly are they, why are they so important and how are they measured in laboratory medicine?

What are hormones?

Hormones are chemical messengers that our body produces itself. They are released into the blood by glands – such as the thyroid gland, adrenal glands or pituitary gland – and then travel to various organs and tissues. There they send signals that regulate important functions. Think of hormones as little commands: They tell the body when to grow, burn energy, calm down or react to stress. Without hormones, many things in the body would not work, from digestion to sleep to reproduction.

There are many different hormones, but some are particularly well known: Insulin controls blood sugar, adrenaline makes us alert and fast in danger, and oestrogen or testosterone influence development during puberty and fertility. Each hormone has a specific task, and they often work together like a well-coordinated team.

Why are hormones important?

Hormones are vital because they keep the body in balance – experts call this “homeostasis”. When this balance is right, we feel good: we have energy, sleep normally and can cope with stress. However, if the hormone balance is disturbed, we quickly notice this. For example, too little thyroid hormone (thyroxine) can make us tired and sluggish, while too much can make us nervous and sweaty. A lack of insulin leads to diabetes, and an imbalance in sex hormones can affect fertility or the menstrual cycle.

In Germany, hormone disorders are a common reason why people go to the doctor. They can be caused by illness, stress, diet or age. This is why it is so important to keep an eye on hormone levels – they give an indication of what is going on in the body and help to identify and treat problems at an early stage.

How are hormone levels determined in laboratory medicine?

In laboratory medicine, hormone levels are usually measured via blood tests, sometimes also via urine or saliva, depending on the hormone. In Germany, the procedure is simple: the doctor takes a sample – usually blood from a vein in the arm – and sends it to the laboratory. There they examine exactly how much of a certain hormone is circulating in the body.

The most important hormones that are regularly tested are, for example:

• Thyroid hormones (TSH, T3, T4): These show how well the thyroid gland is working. TSH (thyroid-stimulating hormone) is produced by the pituitary gland and regulates the thyroid gland. It is often measured in the laboratory using an immunoassay: Antibodies recognize the hormone and generate a measurable signal, for example through light or color. Standard values for TSH in Germany are usually between 0.4 and 4.0 mU/l (milli-units per liter), but can vary slightly depending on the laboratory.
  
• Insulin: This hormone is produced in the pancreas and is crucial for blood sugar. It is also determined in the laboratory using immunoassays, often together with the blood glucose level, in order to diagnose diabetes. Normal values depend on whether you are fasting, but are usually around 2-25 µU/ml (micro-units per milliliter).
• Sex hormones (oestrogen, testosterone): These are tested for problems such as infertility or menopausal symptoms. An immunoassay is also used here. Testosterone is normally between 3 and 10 ng/ml (nanograms per milliliter) in men, and much lower in women. Oestrogen varies depending on the phase of the menstrual cycle in women.
  
• Cortisol: The stress hormone from the adrenal glands is often measured to check for stress disorders or Cushing’s syndrome. It can be tested in blood, saliva or urine, with normal values that fluctuate depending on the time of day (higher in the morning, lower in the evening).

Laboratory medicine uses state-of-the-art equipment that works very precisely. It is often also checked whether hormone production is controlled by other substances – for example, whether the pituitary gland is sending enough signals. This makes the diagnosis more precise.

What happens to the results?

After the analysis, the doctor discusses the values with the patient. If they are too high or too low, he looks for the cause: Is a gland overactive or underactive? Is there a disease? Or is medication affecting the values? Depending on the result, treatment may follow, for example with hormone tablets for thyroid problems or insulin for diabetes. Sometimes a change in lifestyle, such as less stress or a better diet, is enough.

Conclusion

Hormones are the invisible conductors of our body – they control almost everything, from growth to mood. In Germany, laboratory medicine helps to precisely measure their levels and detect any disruptions. Using simple tests and modern methods, doctors can find out whether the hormone orchestra is playing in harmony and intervene if something is out of sync. In this way, hormones not only ensure balance in the body, but laboratory medicine also provides clarity in diagnosis.

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Gender note. The personal designations used in this text always refer equally to female, male and diverse persons. Double/triple references and gendered designations are avoided for the sake of better readability ected.