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Vitamin D

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Created: 07/02/2024
Edited: 24/02/2026
Written by: Carlota Pano

What is analysed?

Vitamin D is an essential fat-soluble vitamin that plays an important role in various physiological functions, including calcium and phosphate regulation, immune system function, bone health, and cellular growth and differentiation. The vitamin D test measures vitamin D levels in the blood.



What does the result mean?

The result indicates the concentration of vitamin D in the blood.



Why conduct the analysis?

The vitamin D test is conducted to evaluate dietary intake and sunlight exposure, and assess the risk of rickets and osteomalacia.



When to conduct the analysis?

The vitamin D test is conducted when symptoms of vitamin D deficiency, such as bone pain, muscle weakness or fatigue, are observed. The analysis may also be conducted during bone health assessments and regular monitoring of patients at risk for vitamin D deficiency like elderly patients.



What sample is required?

A blood sample is used for the analysis of vitamin D levels. The blood is drawn from a vein, usually in the arm.



Is any prior preparation necessary?

Patients should fast for 8-12 hours before the blood sample is taken. In addition, patients should also inform a healthcare professional about any medications being taken, as they could affect results.



How is it performed?

The collected sample is sent to a laboratory, where it is analysed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) or immunoassay techniques to quantify vitamin D levels in the blood.



What are the normal values?

The table below outlines how vitamin D status is classified based on blood concentration ranges.




What does having altered values mean?

  • Low levels: Low vitamin D levels indicate vitamin D deficiency, which can lead to bone conditions such as rickets and osteomalacia.
  • Elevated levels: Raised vitamin D levels can lead to hypercalcaemia (too much calcium in the body), which can cause weakened bones and damage to the kidneys and the heart.


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