Vitamin D is an essential nutrient that helps your body absorb calcium and maintain strong bones.

This test is important because vitamin D deficiency can lead to weak bones, muscle weakness, and increased risk of fractures. It can also affect your immune system, making you more susceptible to infections. 

Vitamin D comes from two sources; it can be ingested from foods and supplements, or be produced in the skin once it is exposed to sunlight.

Vitamin D tests are used to identify vitamin D deficiency and to monitor disease that interfere with fat absorption like Crohn’s disease.

The test measures the level of folate, also known as vitamin B9, in the blood serum. Folate is an essential nutrient that plays a crucial role in DNA synthesis, red blood cell production, and cell division.

Someone may have this test done for several reasons:

1. To diagnose folate deficiency: Low levels of folate in the blood can indicate a deficiency, which can lead to symptoms like fatigue, weakness, pale skin, and difficulty concentrating.

2. To monitor folate levels during pregnancy: Adequate folate levels are crucial during pregnancy to prevent neural tube defects in the developing fetus. This test helps ensure that the pregnant individual has sufficient folate levels.

3. To assess the effectiveness of folate supplementation: Individuals who are taking folate supplements or undergoing treatment for folate deficiency may have this test to monitor the response to treatment and adjust the dosage if needed.

4. To investigate certain medical conditions: Folate levels can be affected by certain medical conditions like malabsorption disorders, liver disease, alcoholism, and certain medications. This test can help identify the underlying cause of abnormal folate levels in such cases.

Vitamin B12 is a vitamin which is necessary for the formation of red blood cells, tissue and cellular repairs, and nerve health. 

It is primarily found in animal products such as meat, fish, milk and eggs, so it is particularly relevant to anyone on a plant based diet.

This test measures the total amount of vitamin B12 in the blood. It may contribute to the diagnosis of vitamin B12 deficiency, pernicious anemia, malabsorption disorders, and certain gastrointestinal conditions. 

In males and females, low levels of vitamin B12 can lead to anaemia, fatigue, weakness, and neurological symptoms. 

In females, low levels of vitamin B12 can also lead to complications during pregnancy.