The blood levels of vitamin B6 are measured by the vitamin B6 test. Although this vitamin is often obtained through diet, those who are lacking in other B complex vitamins may also be lacking in it. A vitamin B6 deficit is more likely in persons with autoimmune, intestinal, liver    or kidney problems. Additionally, those who smoke, are overweight, are alcoholics    or are pregnant may also be deficient in this vitamin. Protein, carbohydrates    and fats are processed by the body with the help of vitamin B6. Additionally, it is necessary for the immune system and nervous system to work properly.