Preparing for a blood test may require, for example, fasting or leaving out some medications. Not taking medications should be discussed with your doctor.
Puhti handles all of your laboratory test needs without a doctor’s referral. On this page, you will find instructions for testing and, for example, fasting.
It is important to prepare for your blood tests correctly so that the results will be reliable and useful.
Please note that the methods of analysis, test codes and instructions may vary, depending on the laboratory. Puhti test samples are collected and analysed at the laboratories of Mehiläinen.
We take care of the well-being and safety of our customers and staff. Do not visit the laboratory if you are ill. The order placed on the Puhti website is valid for one year, and you can visit the laboratory for testing when it suits you and when you are healthy.
Usually, a blood test can be taken, no matter what or when you have eaten. A light meal may be eaten prior to the test, but caffeinated beverages (coffee or tea) should be avoided.
If the test requires fasting, it is mentioned on the product page. Most of the Puhti test packages do not require fasting.
Avoid alcohol and smoking the day before the test. Stimulants can affect the body’s hormone and enzyme levels, blood glucose and fluid balance, among other things.
Intense exercise can affect the results. We recommend avoiding heavy physical exertion during the 24 hours before the test. Exercise changes blood plasma volume, metabolism and cell permeability. This affects the levels of glucose and various hormones, among other things.
We recommend avoiding supplements the day before the test, as they may distort the test results. It is advisable to pause iron supplements 1-2 weeks before sampling when examining iron stores.
Creatine used as a dietary supplement can increase creatinine levels. Those taking creatine as a supplement should take a week off before sampling.
It is recommended to pause biotin the day before the sample collection, as it may interfere with DHEAS and SHBG analyses.
As a rule, medicines prescribed by the doctor may be taken as usual before the test. Not taking your medication should be discussed with your attending doctor prior to testing.
If you are having testosterone replacement therapy and using a topical gel, you need to avoid applying the gel on your forearms before testing. Testosterone gel on the forearm may yield incorrect testosterone test results.
The sample is taken before the thyroid medicine or four hours after taking the medicine. The concentration is the most even between 10 a.m. and 8 p.m.
Many of the Puhti test packages do not require fasting. You can find detailed information on the product page in the Puhti online. However, fasting is required for some blood tests. If your test requires fasting, you should not eat or drink for 8–12 hours before the test. Do not fast for longer than 14 hours. Tests that require fasting are usually carried out in the morning after an overnight fast.
Avoid drinking a lot of water or soft drinks when fasting before a test. As the test may be affected by alcohol, coffee, tea and tobacco, please avoid them even when fasting. In the morning before the test, you can drink a glass of water and take the necessary medicines (do not skip your medication without your doctor’s advice).
However, do not fast unless specifically instructed to do so in the instructions for the test.
If you add individual tests to a ready-made test package, you can identify fasting-required tests by the small ‘f’ in front of the test abbreviation (for example, folate, fS-Folate). If your order includes even one fasting-required test, fast before the sample collection.
Fasting-required tests in Puhti’s selection are:
The following Puhti test packages require fasting:
Before testing, we recommend that you sit still for about 15 minutes to allow your blood circulation to stabilise.
Try to sleep, eat, drink, exercise and work normally during the days before the test. Intense stress or sorrow, for example, can significantly affect the values.
Some blood tests must be carried out at a specific time of day. The functioning of the body and the concentration of hormones and compounds in the body vary according to the time of day, which is why it is important to test them at the recommended time. See the detailed instructions in the email you received after placing your order or on the product pages of the Puhti online store. You can book an appointment at the Mehiläinen laboratory if you have a test or a test package that requires a certain time of day.
Puhti tests requiring a specific time of day:
Note! It is advisable to pause iron supplements 1-2 weeks before sampling.
Chlamydia and gonorrhea from a urine sample: First urine, no washing before sampling. You must not urinate for 2 hours before sampling.
The study does not require fasting. The test can be done at any time of the day. Additional information is collected during sampling for the study. Be prepared to answer the following questions in the laboratory:
To collect a sample (calprotectin and salmonella), you need to pick up a sample container from the laboratory. The sample is taken at home. Sampling equipment and instructions are provided at the laboratory. 1-5 g of stool (a teaspoon, no more than half the volume of the sample container) in a well-sealed stool sample container. The outside of the container must be clean. The container is packed in a tight plastic bag. It can be stored for 3 days in the refrigerator, sent at room temperature.
Note! For the Calprotectin test (F-Calpro), avoid using anti-inflammatory drugs for a couple of weeks before testing, as they can distort calprotectin results by giving a false positive.
Puhti laboratory package includes many different tests that give you a wide range of information on how your body is doing. It includes blood count, cholesterol, blood glucose, vitamin D, ferritin, inflammatory status and tests of the functioning of the thyroid gland, liver and kidneys.
Extensive Puhti laboratory package (women) is a great choice when you want to gain more thorough information about the well-being of your body. The laboratory package will help you check how your body is doing and make better choices for your health. Several tests are included, such as cholesterol, blood glucose, vitamins D and B12, ferritin, and sodium.
Extensive Puhti laboratory package (men) is a great choice when you want to gain more thorough information about the well-being of your body. The Puhti laboratory package will help you check how your body is doing and make better choices for your health. Several tests are included, such as cholesterol, blood glucose, important vitamins, ferritin and testosterone.
The total cholesterol measurement shows the total cholesterol value in the blood.
Ferritin indicates the amount of iron stored in the body. Low ferritin level is a sign of low iron stores.
Testosterone is men’s most important sex hormone, the amount of which affects overall health and well-being.
Article updated:
17 January 2025