The vitamin D test, also known as hydroxyvitamin D or 25 (OH) D, aims to test the concentration of vitamin D in the blood, as it is an essential vitamin for regulating blood levels of phosphorus and calcium, having a fundamental role in the bones. metabolism, for example.
This test is usually requested by your doctor to monitor vitamin D replacement therapy or when there are signs and symptoms related to bone descaling, such as muscle pain and weakness, for example, most of the time it is requested with calcium, PTH, and phosphorus in your blood.
- Vitamin D testing is primarily done to diagnose vitamin D deficiency in addition to hypervitaminosis D.
- However.
- Your doctor may also order this test for signs and symptoms of bone descaling.
- As vitamin D is one of the factors responsible.
- To regulate the concentration of calcium and phosphorus.
- As well as to promote bone mineralization.
This test is also needed to control vitamin D replacement therapy and to aid in the differential diagnosis of rickets, osteoporosis and osteomalacia, which is a disease characterized by brittle and brittle bones in adults. To do this, in addition to the dose of vitamin D, an assessment of calcium, parathormony and phosphorus levels in the blood can be requested, since phosphorus is also linked to the bone formation process. Understand how blood tests are done to detect phosphorus.
Além de ser indicada para investigar hipo e hipervitaminose e alterações ósseas, o exame de vitamina D é indicado para pessoas que são consideradas grupo de risco, que são aquelas acima dos 60 anos, que tenham contraindicação à exposição solar ou que não se expõem regularmente ao sol, gestantes e mulheres em fase de amamentação, pessoas com alterações endócrinas, portadoras de doença renal ou de síndromes de má absorção ou pessoas que façam uso de medicamentos que podem interferir no processo de formação e degradação dessa vitamina.
This indication exists because this group of people has an increased risk of developing complications related to changes in vitamin levels, and it is important that they are regularly monitored and treated according to medical recommendation, which is often done through vitamin supplements. D. Learn more about vitamin D.
To perform the test, no preparation is required, taking a small amount of blood, which is sent to the lab for testing.
Vitamin D is produced from a substance derived from cholesterol in the skin, which, when stimulated by ultraviolet sunlight, is converted into cholesterol, known as vitamin D. The vitamin D produced is metabolized in the liver, becoming 25-hydroxyvitamin D, which in the kidneys, under the influence of parathormony, becomes 1.25-dihydroxyvitamin D, which corresponds to the active and stable form of vitamin D and is responsible for the increase in calcium absorption in the gut and, consequently, the increase in calcium concentration. in the blood.
Both forms of vitamin D are dosed, with 25-hydroxyvitamin D being most commonly used to identify vitamin D deficiency, while 1.25-dihydroxyvitamin D is generally needed for people with kidney disease.
Based on the results of the 25-hydroxyvitamin D dose, it is possible to indicate whether the person has enough vitamin D circulating in the blood to maintain bone health. According to the 2017 recommendation of the Brazilian Society of Clinical Pathology / Laboratory Medicine and the Brazilian Society of Endocrinology and Metabolic [1], the appropriate vitamin D levels are:
In addition, it is determined that there is a risk of toxicity and hypercalcemia when vitamin D levels exceed 100 ng/mL. For levels considered insufficient or deficient studies are carried out for this purpose, however it is recommended that people with values lower than recommended be accompanied by the doctor and, depending on the level identified, start the most appropriate treatment.
Decreased levels of vitamin D indicate hypovitaminosis, which may be due to low sun exposure or low intake of vitamin D-rich foods or their precursors, such as egg, fish, cheese and mushrooms, for example. Discover other vitamin D-rich foods.
In addition, diseases such as fatty liver disease, cirrhosis, pancreatic insufficiency, inflammatory diseases, rickets and osteomalacia, and diseases that cause inflammation of the intestine can cause vitamin D deficiency or deficiency.
Increased vitamin D values indicate hypervitaminosis, which occurs due to the use of large amounts of vitamin D for a long time. Prolonged exposure to the sun does not cause hypervitaminosis, as the body is able to regulate the amount of vitamin D and when optimal concentrations are identified, vitamin D synthesis is indicated by sun stimulation and therefore there are no toxic levels. . vitamin D due to prolonged exposure to the sun.