Vitamin D, a fat-soluble vitamin, is an essential nutrient for individuals of all ages and plays numerous key roles in the human body. Its biological functions include facilitating the absorption of calcium to promote strong joints and bones, strengthening teeth, enhancing immunity, supporting nervous system activity, maintaining cognitive function, maximising lung capacity, and promoting heart health. Vitamin D also contributes to kidney function, supports liver health by regulating blood pH, and plays a role in controlling thyroid gland function. The Vitamin D 25 Hydroxy test, also known as vitamin D test, is a diagnostic assay that measures the quantity of vitamin D in your blood. Keep reading to discover more about the Vitamin D 25 Hydroxy test and what its results indicate.
What are Normal Vitamin D Test Results?
Doctors utilise blood tests to ascertain whether an individual possesses sufficient levels of vitamin D. They measure vitamin D using one of two units: nanograms per millilitre (ng/ml) or nanomoles per litre (nmol/l). The following table outlines approximate ranges for high, low and normal levels of vitamin D for an average adult.
| Low Vitamin D Levels | Normal Vitamin D Levels | High Vitamin D Levels |
| Under 12 ng/mL or 30 nmol/L | Over 20 ng/mL or 50 nmol/L | Over 50 ng/mL or 125 nmol/L |
What Do Abnormal Vitamin D Test Results Indicate?
Your test results may be presented in various formats. They might provide a total vitamin D reading or they could separate the results into vitamin D3 and vitamin D2. Notably, both types of vitamin D function similarly in the body, and the total vitamin D level represents the combined amount of these two types. This total vitamin D figure is the key indicator.
If the total vitamin D level indicates an insufficiency or deficiency, then it could suggest that you:
- Aren’t receiving sufficient vitamin D from sunlight exposure and/or your diet
- Encounter challenges converting vitamin D into a usable form, which may signal kidney or liver issues
- Experience difficulties absorbing vitamin D from your food, potentially indicating a malabsorption disorder
Treatment for low levels of vitamin D usually involves supplements and/or dietary adjustments. This approach is generally safer than increasing sun exposure, which could elevate the risk of skin cancer.
If your total vitamin D level indicates an excess, then it’s typically due to excessive supplementation. Although rare, if this occurs, then you’ll need to discontinue these supplements to lower your vitamin D levels. Excessive vitamin D can lead to severe damage to your blood vessels and organs. If you take vitamin D supplements, then consult your healthcare provider to ask for the ideal dosage for you.
When is a Vitamin D Test Ordered?
Your healthcare provider recommends a vitamin D test if you have signs or symptoms of a bone condition that may be related to a vitamin D deficiency like:
- Muscle weakness or aches
- Bone pain
- Soft bones
- Weak bones and fractures
- Deformed bones
- Low bone density (osteopenia or osteoporosis)
A vitamin D insufficiency (mildly low levels of vitamin D) usually doesn’t cause symptoms. So, your doctor may suggest a test if you are at a higher risk of developing a vitamin D deficiency because you:
- Rarely expose your skin to sunshine as you stay indoors, cover up outside, use sunscreen, or live where there is little sunlight
- Are older than 65. As you age, your skin is less able to make vitamin D from sunlight
- Have dark skin, which makes less vitamin D from sunlight
- Have obesity
- Have had weight loss surgery
- Have kidney or liver disease that affects your ability to change vitamin D into a form your body can use
- Have a condition that makes it difficult to absorb nutrients in food, such as ulcerative colitis, celiac disease and Crohn’s disease
- Take certain medicines that affect your vitamin D levels
If you are taking vitamin D supplements to increase your vitamin D levels, then your provider may order a test to see if your vitamin D levels are improving.
Vitamin D is a crucial nutrient with various benefits, especially for bone health. While sunlight exposure typically provides sufficient vitamin D, individuals at risk of deficiency may find supplementation beneficial. A Vitamin D 25 Hydroxy test can help in assessing your vitamin D levels. Abnormal vitamin D levels can have a variety of causes. Your doctor can help identify the cause and recommend measures to rectify the issue.
Comments
