What is the Vitamin D test and is it accurate?

According to an investigation by JAMA Network, it was found that people suffering from Vitamin D deficiency are 1.77 times more likely to test positive for Covid-19. Vitamin D plays an important role in our bodies by not only strengthening our bones but also ensuring that our immune system functions optimally.

Now the question next would be, how do we know if we’re Vitamin D deficient? Early symptoms of Vitamin deficiency may include hair loss, fatigue, backaches, wounds healing slowly, or even early signs of depression.1 It is tough to pinpoint the root of these symptoms to Vitamin D deficiency as these symptoms are commonly found in many other illnesses. This is why the Vitamin D test is important to accurately diagnose the issue.

Vitamin D Test

The most accurate method to measure the levels of Vitamin D of an individual is to conduct a blood test. Usually called the 25-hydroxy Vitamin D test, it can be commonly carried out in clinics and hospitals. Depending on the clinic or hospital, certain procedures may differ – most places will generally administer a standard blood sample collection procedure. It is the most accurate test to determine the levels of Vitamin D in an individual.

The test measures the levels of 25-hydroxyvitamin D3, also known as Calcifediol which is a form of Vitamin D that is produced in the liver.

Blood samples are usually collected through a vein in the arm. The skin is disinfected before a needle is inserted to collect blood. Once sufficient samples are collected, pressure is then applied to the site to stop bleeding. Individuals can resume normal activities after the process is over.

There are self-test kits available which include a finger prick to draw blood. Despite the convenience of administering the test remotely, it does not give you an instant result as the blood has to be properly tested first. This required the individual to mail the samples out to respective clinics, hospitals, or laboratories, depending on the instructions in the self-test kits. This usually takes a few days to process before the results are either mailed back physically or digitally.


There are many factors when it comes to determining the normal level of Vitamin D needed in a person. The test is measured either in nanomoles per litre (nmol/l) or nanograms per millilitre (ng/ml). With reference to the image below, a test result of below 30ng/ml usually indicates an insufficiency whilst anything below 20ng/ml indicates a deficiency. An optimal amount of Vitamin D would be somewhere around 30ng/ml to 60ng/ml.2

However, what determines an optimal range for a person depends on a multitude of other factors. Doctors take into consideration age, existing medical conditions, medication, skin colour (due to high amounts of melanin), and lifestyle.3 This will also determine the treatment needed and the amount of Vitamin D dose that a person would require to get their Vitamin D to a normal range.


Treatment varies and depends on the severity of the deficiency. Most of the time, patients are given Vitamin D3 supplements to help increase their dose. Diet and lifestyle changes are also advised to help supplement the amount of Vitamin D a person needs.

When to get tested

Most people usually get tested only after they’ve been diagnosed with issues that stem from Vitamin D deficiency. Many of these issues are usually related to the bone. Having regular check-ups is also crucial when it comes to diagnosing deficiencies early. It is also important to take note of the early signs and to schedule a check as soon as possible; most issues stem from complacency as some of these symptoms are common.

There are many places to get professional consultation and treatment when it comes to Vitamin D3 deficiency. Partnered with over 60 different clinics and medical centres island-wide, Sunshine Vitamin Singapore is adopted by many medical professionals and specialists. We carry Cholecalciferol in Singapore in different presentations including ampoules and sprays. To locate a clinic or medical centre near you, simply click here or you can choose to contact us directly.

1) Healthline Media. “Vitamin D Deficiency: Symptoms, Treatments, and Causes.” Available at: Accessed 29 July 2022.
2) Tello, Monique. “Vitamin D: What’s the “right” level?” 19 December 2016, Available at: Accessed 29 July 2022.
3) Healthline Media UK Ltd. “Vitamin D deficiency: Causes, symptoms, and treatment.” Available at: Accessed 29 July 2022.