25-Hydroxy Vitamin D test


Last Updated December 20th, 2021

What is the importance of vitamin D in the body?

Vitamin D is a significant element in the body that helps the system to absorb calcium and develop strong bones. Multiple pieces of research also point out its effectiveness in keeping the immune system functioning, along with the prevention of cancer and cardiovascular diseases.

It also helps in the prevention of dementia, dental caries, respiratory tract diseases, metabolic diseases. For any person who is on a vegetarian diet and is not absorbing sufficient levels of sunlight, vitamin D deficiency can occur in the body. This may result is severe damage to the bones including soft bones and skeletal deformities.

Spending a moderate amount of time in the sun is one of the most effective ways to generate vitamin D in the body. Its deficiency needs to be closely monitored for individuals like perimenopausal women and people diagnosed with osteopenia, osteoporosis or other skeletal disorders.

What is a 25-hydroxy vitamin D test?

The most accurate way to determine the level of Vitamin D in the body is through the 25-hydroxy vitamin D test. It is widely used to diagnose bone disorders and even for chronic illnesses like asthma and psoriasis.

What are the different forms of vitamin D?

Compared to other vitamins, Vitamin D is quite hard to get from naturally occurring foods and medicines. The two main forms of vitamin D are cholecalciferol (vitamin D₃) or ergocalciferol (vitamin D₂) which can be consumed through food. Cholecalciferol is produced in the skin as a result of UVB radiation.

Why do I need to undergo a Vitamin D test?

The test is done to assess the vitamin D levels in the body so that it can be determined whether you need supplements or more exposure to the sun. Many doctors do not recommend testing in healthy individuals unless there are specific symptoms present. The test is done specifically for some individuals who have the following issues.

– Individuals with a body mass index of 30 or greater and suffering from obesity can have deficiencies.

– Intake of certain medicines like phenytoin, phenobarbital, and rifampin.

– Those diagnosed with osteoporosis, bone weakness or bone softness.
Individuals with limited sun exposure.

– Anyone with diseases like ulcerative colitis, Crohn’s disease or celiac disease prevents the normal absorption of vitamins in the body.

– Previous gastric bypass surgery or weight-loss surgery.

– Inadequate vitamin D absorption due to advanced age or conditions in which fat is not absorbed well in the body.

– People who have dark skin or wear total skin covering are also at risk of a deficiency.

How common is vitamin D deficiency in India?

Even though India receives ample sunlight in most geographic locations, there is widespread vitamin D deficiency ranging from 50-90% of the general population. This is because there is an inherent lack of vitamin D and calcium-rich foods in the average Indian diet.

How is the Vitamin D test performed?

The test is a simple blood test that is conducted on a blood sample derived from your body. A healthcare professional will use a small needle to draw blood from you’re a vein in your arm. The blood is drawn into a syringe connected to the needle. The method is risk-free and you will only feel a slight sting when the needle is inserted in the vein. The entire procedure takes around five minutes to complete. The blood sample is then analyzed to determine the levels of Vitamin D.

What is the price for a Vitamin D test in India? 

In India, the cost for the 25-hydroxy vitamin D test ranges between Rs 500 to 1000 depending on the location and quality of the facilities.

When will I get the test results?

The test results are generally handed over to the patient within a day.

What is the normal range for 25-hydroxy  Vitamin D?

The levels of vitamin D in the body is measured as nanograms per milliliter (ng/mL) or in terms of nmol/l. Most tests provide the levels of both D2 and D3 and then add them together to provide a total level. In the United States, different organizations suggest different normal levels of vitamin D and there have been debates within the medical fraternity regarding the same. As per the vitamin D council, a level of 50 ng/ml is the ideal point to aim for. Any level less than 20 ng/mL indicates vitamin D deficiency.

A report by the Institute of Medicine (IOM) suggests that 20 ng/mL or higher was adequate for good bone health, and a level below 20 can be considered as vitamin D deficiency. Recent research work based on data collected from the National Health and Nutrition Examination Survey (NHANES) suggests that the cut-off for Vitamin D deficiency can be as low as 12.5 ng/mL. The research states that many individuals with such levels are perfectly fine.

In case your levels are above 100ng/mL, it is considered very high. High levels of the vitamin can result in increased absorption of calcium which can lead to the calcification of internal organs. It can lead to a condition called hypervitaminosis D, which can cause kidney damage.

Some studies pointed out that high levels above 150 ng/mL can result in an irregular heartbeat called atrial fibrillation. You should consult your doctor to take the right steps to reduce the levels.

If your levels are between 20-30 ng/mL, you are still deficient as per the Vitamin D Council but your levels are fine as per the Institute of Medicine’s standards. The results can also slightly vary depending on the laboratory and the equipment. Your doctor can analyze the results along with any other symptoms that you have and guide you in the right direction.

The following chart provides a comparative look at the various vitamin D levels suggested by the different bodies.

Vitamin D CouncilEndocrine Society Food and Nutrition BoardTesting Laboratories
Deficient 0-30 ng/ml 0-20 ng/ml 0-11 ng/ml 0-31 ng/ml
Insufficient 31-39 ng/ml 21-29 ng/ml 12-20 ng/ml
Sufficient 40-80 ng/ml30-100 ng/ml >20 ng/ml 32-100 ng/ml
Toxic >150 ng/ml

What do the results mean?

If your results indicate a vitamin D deficiency, it can indicate any one of the following conditions.

– Lack of skin exposure to sunlight, dark skin orheavy use of high SPF sunscreen.

– Your diet does not contain sufficient vitamin D or your body is unable to absorb the right quantity.

– Liver and kidney diseases.

– Some medicines can also lower the levels of the vitamin.

Depending on the results, the doctor can suggest supplementation or additional exposure to the sun. The ICMR recommends only 400 IU (10 mcg) of Vitamin D for people with low exposure to sunlight. For those who are taking supplements, a dose of 1000-2000 IU/ day seems to be safe.

Do I need to fast for the Vitamin D test?

In general, fasting is not required for the test but confirm the same from the clinic in which you will undergo the test.

What else do I need to know before I appear for a Vitamin D test?

For some people locating the right vein can be difficult and hence multiple punctures may be necessary. In some rare cases, there may be blood accumulating under the skin resulting in a hematoma or a slight infection resulting from the puncture. Some people may also bleed excessively from the collection site. There are others who may feel light-headed or certain dizziness when the blood is collected.

Vitamin D deficiency often goes unnoticed and underdiagnosed and hence one needs to be cautious about diet and lifestyle. While vitamin D supplementation is very common, not everybody achieves the same levels with the same amount of supplementation. Most people take vitamin D supplements without side effects but some situations mentioned below may require additional attention.

Combining vitamin D with other medicines like digoxin, primidone, barbiturates or others related to high blood pressure, can result in complications. This can interfere with the action of the vitamin and hence needs a consultation with the doctor.

Those who are suffering from primary hyperparathyroidism, Hodgkin’s or non-Hodgkin’s lymphoma, granulomatous disease or kidney stone need expert consultation before using supplements. In case you have high levels of calcium in the blood, take your doctor’s advice after the tests are done

Can pregnant women undergo a Vitamin D test?

There are no restrictions on pregnant women undertaking the vitamin D test.

Is the vitamin D test prescribed for babies?

Newborn babies can undergo the test as advised by the physician.

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