Vitamin C Intake Measurement (24-Hour)

What This Test Measures

Vitamin C, also called ascorbic acid, is a water-soluble vitamin found in fruits and vegetables. Because the body does not store much of it, excess amounts are passed in the urine. By measuring vitamin C in a complete 24-hour urine collection, this test estimates how much vitamin C you took in from food and supplements during that day.

How the Sample Is Collected

You will be asked to collect all of your urine over a full 24-hour period in a special container provided by the laboratory. The collection usually starts after you empty your bladder in the morning and continues until the same time the next day. The container is then returned to the lab for analysis.

What the Results Can Suggest

Results can help show whether your recent vitamin C intake is low, adequate, or high. They reflect intake over the collection day rather than your long-term vitamin C status. Your care team will interpret the result along with your diet, supplements, and other tests.

How to Prepare

Follow the laboratory's instructions about timing and storage of the collection container. Tell your care team about any vitamin C supplements you take, since they can affect the result. Do not change your diet or supplements unless your healthcare provider asks you to.