Vitamin D3 (1,25-(OH)2-D3 determination)

The Vitamin D3 (1,25-(OH)2-D3) blood test is a laboratory test designed to measure the concentration of the active form of vitamin D in the blood. It is called 1,25-dihydroxyvitamin D3 (or 1,25-(OH)2-D3) determination because it is the bioactive form that plays an important role in the body.

1,25-(OH)2-D3 is the active form of vitamin D, which is formed in several stages in the body. First, the skin, under the influence of sunlight or through food intake, absorbs vitamin D3 (cholecalciferol) and transforms it into 25-hydroxyvitamin D3 (25-(OH)D3) in the liver. Later, the kidneys activate 25-(OH)D3 into 1,25-(OH)2-D3.

1,25-(OH)2-D3 is an important regulator of vitamin D and influences many body functions, including calcium and phosphorus metabolism, bone mineralization, the immune system, and more.

The blood test for determining the concentration of 1,25-(OH)2-D3 can be useful in various circumstances, including:

1. Assessment of vitamin D deficiency: This test can help determine if there is a sufficient amount of the active form of vitamin D in the body, considering the body's ability to produce and absorb it.

2. Diagnosis of bone metabolism disorders: The 1,25-(OH)2-D3 test can be performed to evaluate bone diseases such as osteoporosis or osteomalacia and to assess bone mineralization.

3. Diagnosis of other conditions: Sometimes this test may be performed for patients suspected of having a disease or disorder that may affect vitamin D regulation, such as certain kidney diseases or parathyroid diseases.