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Vitamin D test to detect any deficiency or excess

Important note: The information in this article should be considered general in nature, not specific to anyone, and therefore, it should not be interpreted as specific medical advice nor replace the relationship between the doctor and the patient. To get more advice specific to your condition, you should consult a medical professional.


Vitamin D is a group of compounds necessary for the proper growth and formation of teeth and bones. This test measures the level of vitamin D in the blood.

Two types of vitamin D can be measured in the blood, 25-hydroxyvitamin D and 1,25-dehydroxyvitamin D.

25-hydroxyvitamin D is the main form found in the blood.

What is the importance of vitamin D?

Vitamin D has effects on calcium and phosphorous metabolism and bone health. Vitamin D is thought to be important for maintaining the normal function of many non-skeletal tissues such as muscles (including the heart muscle), improving the immune system and the ability to fight infections, as well as for cell proliferation and differentiation.

Studies have shown that vitamin D may be useful as an adjunct treatment for tuberculosis, psoriasis, multiple sclerosis, or for preventing some types of cancer. Vitamin D deficiency may increase the risk of developing type 1 diabetes, cardiovascular disease ( insulin resistance , high blood pressure, or low-grade infections), or impaired brain function (such as depression). However, the exact physiological roles of Vitamin D, its effect on these diseases, and the significance of these roles have not been elucidated.

Normal levels of vitamin D in the body

Healthy adults ages 19 to 50 should get about 200 international units of vitamin D per day. Older adults must get higher levels to ensure their bones remain healthy. Recommendations for ages 51–70 are 400 IU, and go up to 600 IU for people over the age of 70.

Why is a vitamin D test done?

Vitamin D test is used to determine:

  • Whether there is a weak or deformed bone or an abnormal calcium metabolism (which is reflected by the abnormal calcium, phosphorous, and PTH hormone) that occurs as a result of a deficiency or an excess of vitamin D.
  • It helps diagnose or monitor problems with thyroid gland function since PTH is necessary for the activation of vitamin D.
  • Screening people at high risk of deficiency, as recommended by the National Osteoporosis Foundation, Institute of Medicine, and the Endocrine Society.
  • Helping monitor the health status of individuals with diseases that interfere with fat absorption, such as cystic fibrosis and Crohn’s disease, because vitamin D is a fat-soluble vitamin that is absorbed from the intestine like fat.
  • Monitor people who have had gastric bypass surgery and may not be able to absorb enough vitamin D.
  • Help determine the effectiveness of treatment when prescribing vitamin D, calcium, phosphorous, and / or magnesium supplements.

When is a vitamin D test required?

25 Hydroxyvitamin D analysis

When calcium is low and / or a person has symptoms of vitamin D deficiency, such as bone deformation in children (rickets) and weak or soft bones or fracture in adults (osteomalacia), so a 25-hydroxyvitamin D test is usually required to determine the possibility of a deficiency. In vitamin D.

Testing may be ordered when an individual is known to be at risk of vitamin D deficiency and for the elderly, people without exposure to sunlight, those who are obese, those who have had gastric bypass surgery, and / or who have poor lipid absorption are at risk. Increased vitamin D deficiency. This group also includes dark-skinned people and women who are breastfeeding .

Often a 25-hydroxyvitamin D test is required before a person begins treatment with drugs for osteoporosis.

An analysis of 1,25 dehydroxyvitamin D.

This test may be ordered when kidney disease or abnormalities in the enzyme that converts 25 hydroxyvitamin D to 1,25 dihydroxyvitamin D are suspected.


In rare cases, this test may be done when the calcium is high or the person has a disease that may produce excessive amounts of vitamin D, such as sarcoidosis or some form of lymphoma (because immune cells may make 1,25 dihydroxyvitamin D).

When vitamin D, calcium, phosphorous, or magnesium is necessary, vitamin D levels are sometimes measured to monitor the effectiveness of treatment.

What does the result of the vitamin D test mean?

Although there are differences in methods of analyzing vitamin D, most laboratories use similar reference periods.

The American Endocrine Association defines vitamin D deficiency if the level of 25-hydroxyvitamin D in the blood is less than 20 ng / ml (50 nmol / L) and vitamin D failure if the level is between 21-29 ng / ml (52.5 – 72.5 nmol / liter).

The Institute of Medicine of the United States concluded that a 25-hydroxyvitamin D level of 20 ng / mL (50 nmol / L) or higher is appropriate for bone health, and that levels greater than 30 ng / mL do not provide significantly better effects. However, it is fair to say that the 25-hydroxyvitamin D level associated with protection against many other disorders recently associated with vitamin D deficiency is controversial.

25 Hydroxyvitamin D.

A low level of 25-hydroxyvitamin D in the blood may mean that a person is not getting enough periods of exposure to sunlight or enough nutritional vitamin D to meet their body’s needs or that there is a problem absorbing it from the gut.

Occasionally, medications used to treat seizures, especially phenytoin (Dilantin), can interfere with the production of 25-hydroxyvitamin D in the liver.

There is some evidence that vitamin D deficiency may increase the risk of some cancers, immune diseases, and cardiovascular disease.

A high level of 25-hydroxyvitamin D is usually caused by excess supplementation from vitamin tablets or other nutritional supplements.

1,25 dehydroxyvitamin D.

The level of 1,25 dihydroxyvitamin D can be low in kidney disease, which is one of the changes that occurs in people with early kidney failure.

A high level of 1,25 dihydroxyvitamin D may occur when there is an excess parathyroid hormone or when there are diseases such as sarcoidosis or some lymphomas which can manufacture 1,25 dihydroxyvitamin D outside the kidneys.

High levels of vitamin D and calcium can lead to calcification and damage to organs, especially the kidneys and blood vessels.

How can I get vitamin D to avoid any deficiency?

Vitamin D is obtained naturally during exposure to sunlight. White people are able to obtain this vitamin easily because they have less melanin to protect their skin (which is also the reason why their skin gets sunburned so easily). Dark skinned people in colder regions like Northern Europe often need to take vitamin D supplements because they do not get enough of this vitamin from the sun naturally, due to the reduced sunlight in the colder months.

However, vitamin D must be obtained during the winter because it helps treat seasonal winter depression . We often feel upset and sad when we are deprived of vitamin D. Think about the happy feeling you feel in early spring when the sun rises while the weather is still cold.



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