The average human body has approximately 5 liters of blood coursing through it. To visualize how much that is, picture a 2-liter soda bottle. There’s enough blood in the average human body to fill up about two-and-a-half of those. Whether that sounds like a lot or a little, it can sometimes feel like your doctor wants all 5 liters at once if you’re living with lupus.

“Has anyone had their rheumatologist order 36 blood tests requiring 15 vials of blood?” asked one MyLupusTeam member. Another replied, “Yes. I looked at the phlebotomist like she was crazy. She said my doctor was just being thorough, and it was better than getting stuck twice.”

In this article, learn why you might need blood tests for lupus, how much blood the laboratory technician can safely draw at once, and how to make future blood collections less stressful.

Blood Tests for Lupus

Blood can communicate a lot about what’s going on inside your body. Health care professionals rely on venipuncture (using a needle to obtain blood samples from a vein) to measure levels of glucose (blood sugar), electrolytes, hemoglobin, potassium, and more.

Here are a few blood tests your doctor might order for diagnosing or treating lupus:

• Complete blood count (CBC) to measure red blood cells, white blood cells, platelets, serum, and hemoglobin, a protein in red blood cells
• Antinuclear antibody test to detect antinuclear antibodies, which are often elevated in people with autoimmune diseases, and help confirm a lupus diagnosis
• Erythrocyte sedimentation rate to detect inflammation and help confirm a lupus diagnosis
• Antiphospholipid antibody test to assess the risk of blood clots
• Creatinine test to assess kidney function
• Blood urea nitrogen to assess kidney involvement and liver function
• Fasting lipid profile to measure cholesterol and evaluate heart disease risk, a common issue in people with lupus

The above list is not exhaustive. Your care team may order additional blood tests to confirm a lupus diagnosis or monitor disease progression and how you respond to lupus treatments. If you have questions about your test results or the different types of tests, schedule an appointment with your health care provider.

Blood Collection Volumes

Your doctor might request up to 30 milliliters of blood for a CBC. It can look like a lot if you’re watching it fill up a vial, but 30 milliliters of blood is equivalent to around 2 tablespoons. In other cases, they may take only 10 milliliters, or around 2 teaspoons. For comparison, a typical blood donation is about 450 milliliters — about the amount in a standard pint glass.

Your doctor might request more than 30 milliliters for laboratory testing if you need different types of tests. Ordering it all at once minimizes the number of times you get stuck with a needle. On average, a healthy adult can safely give up to 550 milliliters of blood (around 37 tablespoons) over an eight-week period.

There are a few reasons your safe sample volume might be lower than 550 milliliters:

• Overall health — If you are at risk of anemia, have bone marrow issues, are undergoing chemotherapy, or have other medical concerns, your maximum amount might be lower.
• Body weight — The amount of blood drawn over eight weeks should be limited to 10.5 milliliters per kilogram (around 2.2 pounds) of your body weight, if that number is less than 550 milliliters.
• Age — For children 12 and under, pediatric experts recommend whichever of the following is lowest: 2.4 milliliters per kilogram of body weight, 50 milliliters, or 3 percent of the child’s total blood volume.

If you are under the care of multiple health care professionals, make sure the one requesting blood work for lupus is aware of any treatment you are receiving, including blood clotting or thinning medications or blood transfusions, as well as health conditions you may have, such as anemia.

How Much Blood Is in a Testing Vial?

It can seem like the phlebotomy team is taking too much blood at once if they fill multiple blood collection tubes. But each vial might hold less blood than you think.

A standard adult testing vial usually holds 3 to 10 milliliters of blood, which is around 2 teaspoons or less. A pediatric testing vial can hold 2 to 4 milliliters of blood, less than 1 teaspoon. For a fingerstick or heel stick, the tube will likely hold 0.5 milliliters or less.

Even if your blood fills 10 10-milliliter tubes, 100 milliliters is less than the standard donation amount (450 milliliters) and the maximum recommended level (550 milliliters).

Also, most vials are not empty when blood starts flowing into them. Test tubes have different colored caps to indicate which additives are inside based on the type of test needed. One test tube might have an anticoagulant like potassium EDTA or sodium fluoride to prevent blood from clotting, while another might have a clot-activator gel to speed up coagulation.

If you have questions about blood vials or concerns about the amount of blood your health care provider ordered, ask. And if your stress levels rise as the vials fill, take a deep breath and remember that other people with lupus understand what you are going through.

“I used to make a game out of seeing what my high number was,” said one MyLupusTeam member. “I think my record draw is 18 vials.”

Another MyLupusTeam member said, “My highest number is 23 vials at once.”

Tips for Your Next Blood Draw

If blood draws make you anxious, you are not alone. Watching blood flow out of your body into a blood collection tube or vial can be nerve-wracking for anyone. And the fear of needles is so common that it has a name: trypanophobia.

Although you can’t avoid blood work if you have a chronic health condition like lupus, you can take steps to improve your experience. Here are a few tips for better blood draws:

• Tell the person drawing blood that you are nervous before they start.
• Look away while they apply the tourniquet and insert the needle.
• Practice deep breathing or meditation.
• Read a book or scroll through social media to avoid watching the blood collection tube or vial fill up.
• Bring headphones and listen to relaxing music.
• Ask a friend or family member to sit with you.
• Speak up immediately if you feel lightheaded or queasy.

If you’re anxious because the person drawing your blood last time stuck you multiple times as they looked for a vein, trying drinking water before your next appointment. Being hydrated increases the volume of blood in your body, making it easier for the nurse or technician to find your vein on the first try.

You can also ask your health care provider for help. Depending on the severity of your discomfort or anxiety, they may prescribe medication, refer you to a therapist, or offer additional coping solutions. You do not have to suffer through blood draws. Ask for the help you need.

Talk With Others Who Understand

MyLupusTeam is the social network for people with lupus and their loved ones. On MyLupusTeam, more than 223,000 members come together to ask questions, give advice, and share their stories with others who understand life with lupus.

Do you have any tips for lupus blood draws? Share your experience in the comments below, or start a conversation on your Activities page.