Vitamin D deficiency is common in many parts of the world. Research indicates that we may need more vitamin D than previously thought, and the Swedish Food Agency has therefore raised its recommendations for daily intake. One reason more people may be deficient is that we spend more time indoors. Other important factors include age, skin pigmentation, disease and whether you have access to foods fortified with vitamin D.

Vitamin D deficiency can have serious consequences, so it can be useful to test your levels in order to detect a deficiency early. It is easy to check vitamin D levels yourself with a self-test. A simple blood sample can be used to measure the vitamin level and indicate whether you have a vitamin D deficiency.

Why is it important to test vitamin D levels?

The main source of vitamin D is sunlight during the summer months, when the body produces the vitamin in the skin in response to sunlight. However, more and more people spend a large proportion of their time indoors. This is particularly common among children and adolescents, but also among adults who work in offices or spend a lot of time at a computer.

We can also obtain vitamin D through our diet. However, it can be difficult to get enough from food alone, so more people may need supplements. Because excessively high amounts can be toxic and high levels can lead to other serious conditions, it is important to establish that you have a deficiency before starting supplements.

What happens in the body if we get too little vitamin D?

All cells in our body that depend on vitamin D need an adequate level of the vitamin to function optimally. Research indicates that vitamin D deficiency may be more serious than previously thought, and an increasing number of associations with serious diseases have been observed.

Most people only know that vitamin D deficiency can lead to osteoporosis. Today, associations are also being studied with serious conditions such as multiple sclerosis, cardiovascular disease, diabetes, depression, stroke, autoimmune diseases, influenza, various cancers, infectious diseases, Alzheimer's disease, obesity and higher mortality. Vitamin D deficiency is not necessarily the cause in these cases, but may be a contributing factor.

It is therefore important to detect deficiencies early, both to support bone health and to improve general health and well-being.

Before vitamin D deficiency leads to serious problems, some symptoms may appear whose underlying cause is worth investigating. These can include extreme fatigue, low mood and irritability, depression, poor appetite, weak muscles and reduced endurance. Cramps can also occur in severe deficiency, although this is very uncommon in Sweden. Several of these symptoms may be unrelated to vitamin D deficiency and can have entirely different causes. It can therefore be important to test for vitamin D deficiency before taking additional supplements.

What does a self-test measure?

Vitamin D, which is actually a steroid hormone, occurs in two different forms. One is D2, found in mushrooms and fortified foods, and the other is D3, produced in our skin and found in foods such as fish, meat and eggs. Vitamin D is fat-soluble, which means it is absorbed most effectively through the intestine when consumed together with some fat. From the intestine, vitamin D is transported to the liver, where it is metabolized into 25-hydroxyvitamin D.

A blood sample can therefore be used to measure 25-hydroxyvitamin D in the blood and determine the concentration of vitamin D in the body. Measuring the blood concentration of both D2 and D3 through 25-hydroxyvitamin D is considered the best indicator of vitamin D status.

How to perform a self-test

A test kit contains everything you need to perform a test.

Use a sterile lancet to prick a finger and obtain a drop of blood for the sample. You may need to press the finger gently to produce a blood drop. Use the pipette to transfer the drop from your finger to the test included in the package. Then follow the instructions for performing the test. While the test processes the blood sample, wait for exactly the time stated in the instructions - neither longer nor shorter. Finally, read the test and interpret the result according to the instructions for use.

Always read the instructions for use carefully before performing a test. A test is reliable only when all instructions are followed correctly. It is also important to wash your hands thoroughly with soap and water and dry them carefully before testing. This helps prevent dirt or bacteria from entering through the finger prick and helps provide the most reliable result possible.

How reliable is a self-test and what test values are used?

A vitamin D test measures the total level of 25-hydroxyvitamin D. The reference value for vitamin D levels is 30 ng/ml ± 4 ng/ml.

A self-test showing a result below 30 ng/ml is 100% reliable, while a value above 30 ng/ml has a stated reliability of 93.33%.

When a self-test shows vitamin levels that are too low

If the test shows that the levels are insufficient, this indicates vitamin D deficiency. Treatment may then involve increasing vitamin D intake through food or supplements. If the test shows insufficient levels, contact a physician to rule out other causes and receive appropriate treatment.