Fasting tests and diurnal variation – how to know what is required before your test

Fasting tests

Some blood tests require fasting before sampling. Fasting means that you should not eat or drink anything containing calories for at least 10 hours before your test. You may, however, drink a glass of water. Any medications should be taken as usual unless your doctor has instructed otherwise.

A fasting test means that you:

• do not eat or drink (except for one glass of water) for at least 10 hours before the test
• take your medications as usual, unless instructed otherwise

Example of a 10-hour fast:

If your appointment is at 08:00, you should begin fasting no later than 22:00 the evening before. During the fasting period, you may drink water as well as black coffee or tea (without milk or sugar).

Examples of tests and health checks that require fasting:

• Triglycerider
• Testosteron
• Glukos
• Hälsokontroll - Man
• Hälsokontroll - Kvinna
• Hälsokontroll - Sport
• Hälsokontroll - Testosteron Plus
• Hälsokontroll - Lagom
• Hälsokontroll - Depression
• Hälsokontroll - Diabetes
• MR Helkropp Plus
• MR Helkropp Pro

How to find what applies to your specific test

Information about fasting and other preparations is always available under the section “Before your test” on the page for the health check or test you have purchased.

Diurnal variation

Some blood tests are affected by the body’s natural diurnal variation. This means that values can vary depending on the time of day, and therefore the test may need to be taken in the morning – often before 10:00.

If this applies to your test, it will be clearly stated under “Before your test” on the test page.

Why do I need to rest for 15 minutes before sampling?

Reference values for many analyses are based on samples taken after the person has been seated and resting for approximately 15 minutes. To ensure your results are as accurate as possible, it is therefore important to sit down and rest before your test.

Medications and supplements

Certain medications and supplements can affect your test results. To obtain the most reliable values, it is important to follow the correct preparations before testing.

General guidelines:

• Delay taking thyroid medication (e.g. Levaxin) until after sampling when testing thyroid markers
• Avoid supplements or medications with high levels of biotin before tests that include thyroid markers
• Avoid taking iron supplements on the same day as the test if your test includes iron markers

Other hormone medications and supplements may also affect your results. If you are unsure what applies to you, consult your doctor.

Any specific instructions regarding medications or supplements are always stated under “Before your test” on your test page.

Need help?

If you have questions about how to prepare for your test, you are welcome to contact our customer support via email or phone. You can also find relevant information when activating your referral in our test results service.

Do you have medical questions?

Our support team can help with practical questions, but cannot provide medical advice or recommendations regarding which test to take or how to manage medications. For such questions, please contact your healthcare provider or doctor.