Endocrine laboratory testing

Endocrinology and hormone tests

Endocrinology is the medical specialty that deals with the hormonal system and the detection of its disorders.
Hormones are the body’s “chemical messengers”: they are produced by the pituitary gland, the thyroid, the adrenal glands, the pancreas, the sex glands and other organs, and play a vital role in keeping the body in balance.

Hormones control growth, metabolism, blood sugar, body weight, mood, the stress response, the menstrual cycle and fertility – in other words, almost every physical and mental process.
If a problem arises at any point in hormonal regulation, it can affect how the whole body works.

The aim of hormone tests is to uncover these imbalances and support an accurate diagnosis and targeted treatment.

What does the endocrine laboratory test?

In hormone tests, the laboratory measures the amount of hormones, how they work and their ratios to each other from blood, urine or saliva.
Because the hormonal system is a network of interconnected glands, the measurements reflect not just the function of individual organs but the state of the whole regulatory chain.

The most commonly tested hormone systems and their main laboratory markers are:

1. Thyroid hormones

The thyroid is responsible for regulating metabolic rate, body temperature, energy levels and heart rhythm.
Thyroid function is controlled by TSH (thyroid-stimulating hormone), produced by the pituitary gland, which regulates the production of the hormones T3 (triiodothyronine) and T4 (thyroxine).

The values measured in the laboratory help determine whether the gland is underactive or overactive.

• Raised TSH and low T4 → underactive thyroid (hypothyroidism).
• Low TSH and high T4 → overactive thyroid (hyperthyroidism).

If needed, an autoimmune cause can also be tested for (e.g. anti-TPO, anti-TG antibodies), which helps detect Hashimoto’s thyroiditis or Graves’ disease.

Regular thyroid hormone checks are recommended for tiredness, hair loss, mood disorders, weight fluctuation, menstrual disorders or infertility.

1. Adrenal hormones

The two main parts of the adrenal gland produce different hormones:

• the cortex produces cortisol, aldosterone and androgens,
• and the medulla produces adrenaline and noradrenaline.

These hormones play a role in regulating the stress response, blood pressure, water and salt balance, and metabolism.

Measuring cortisol levels helps detect Cushing’s syndrome (overproduction) or Addison’s disease (underproduction).
The renin–aldosterone ratio is important in investigating hormonal causes of high blood pressure.

Adrenal hormone tests are often done at a set time of day, as cortisol production follows a natural daily rhythm.

1. Sex hormones

Measuring male and female sex hormones (oestrogen, progesterone, testosterone, LH, FSH, prolactin) helps uncover the causes of fertility problems, menstrual disorders, reduced libido or menopausal symptoms.

• LH (luteinising hormone) and FSH (follicle-stimulating hormone) levels show how the ovaries and testes are working.
• Oestrogen and progesterone testing allows the female cycle and hormonal balance to be assessed.
• Testosterone testing helps clarify hormone deficiency in men, and the causes of excess hair growth or PCOS in women.
• Prolactin levels can rise with stress, medication or a pituitary abnormality.

A hormonal assessment is always tailored to the individual, adjusted to the menstrual cycle, age and complaints.

1. The pancreas and blood sugar control

The hormones of the pancreas, mainly insulin and glucagon, are responsible for regulating blood sugar.
For early detection of insulin resistance and diabetes, the following are often tested:

• fasting blood sugar and insulin levels,
• and the HOMA index, which shows how sensitive the cells are to insulin. This is a calculated value, and working it out requires the fasting blood sugar and insulin results.

Insulin and C-peptide levels help distinguish between different types of diabetes, while HbA1c shows average blood sugar over the long term.

1. Other hormone tests

Some hormones affect several of the body’s systems, for example:

• growth hormone (GH) and IGF-1: responsible for growth, muscle development and regeneration at cell level.
• parathyroid hormone (PTH): regulates calcium–phosphate metabolism.
• melatonin: controls the sleep–wake cycle.

Testing these may be justified for specific complaints, such as sleep disorders, bone metabolism disorders or hormonal developmental disorders.

When is hormone testing recommended?

Hormone testing may be advisable if any of the following symptoms appear:

• persistent tiredness, sleep problems, mood swings,
• sudden weight change or a metabolic disorder,
• menstrual problems, infertility, low libido,
• hair loss, increased hair growth or skin problems,
• heavy sweating, palpitations, nervousness,
• unexplained swings in blood pressure.

A hormone test can also be useful when you have no symptoms, for example as a yearly check-up, when planning a pregnancy, at menopause or before a lifestyle change.

Sample collection and test conditions

Most hormone tests are done on a venous blood sample, but in some cases a saliva or urine sample is also needed.
Hormone levels often change in a daily rhythm, so the doctor may set the exact time of the blood draw (e.g. around 8 am).

Important things to know before your sample is taken:

• before the test, do not eat, only drink water;
• avoid stress and strenuous physical activity;
• do not take any medicines or vitamins on the morning of the test (unless your doctor tells you otherwise);
• in women, some hormones can only be measured accurately on specific days of the cycle.

If the instructions are not followed, hormone levels can be distorted, so for an accurate diagnosis it is essential to prepare correctly.

The role of hormone tests in staying healthy

The fine balance of the hormonal system determines how we feel, how much energy we have, and our general well-being and vitality.
Hormone tests give us the chance to spot small shifts in time, before they cause lasting problems.

Endocrine tests are not only diagnostic but also extremely important for prevention – they help maintain physical and mental balance and quality of life.