Vitamin C

You should get a vitamin C test if you have bleeding gums, easy bruising, slow wound healing, joint pain, fatigue, or frequent infections. It is also recommended for people with a poor diet, smoking habits, alcoholism, malabsorption, or kidney disease, and when doctors suspect scurvy or need to monitor high-dose vitamin C supplementation.

Fasting for 8–12 hours is usually recommended before a vitamin C test, and you may drink water during this time. Avoid vitamin C supplements and vitamin C-rich foods like citrus fruits for about 24 hours before the test, and avoid smoking and alcohol. Inform your doctor about any medicines you take, and follow your lab's instructions.

Yes, fasting is usually recommended for a vitamin C test. You should fast for 8–12 hours before giving your sample, though drinking water is allowed. Also avoid vitamin C supplements and citrus fruits for about 24 hours beforehand, as they can raise your levels temporarily and affect the results.