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How to be a Good Patient Advocate: Understanding Nutrition-Related Labs

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How to be a Good Patient Advocate: Understanding Nutrition-Related Labs

Part of being a good IBD patient advocate is knowing which nutrition-related labs to ask for and why they are important for maintaining optimal health. Your doctor will likely welcome your participation in ensuring that your health is a priority. Below are some nutrition-related lab values that are important for managing IBD. Even if the foods you regularly eat do contain a variety of the nutrients below, IBD poses unique challenges through impaired nutrient absorption, bleeding, and/or inflammation that make maintaining adequate amounts of these nutrients difficult. Ultimately, you know your body, and if you notice that you are experiencing debilitating fatigue, this is a cue to reach out to your doctor. By achieving and working to maintain normal values of these labs, you could avoid fatigue relating to nutrient deficiency altogether and maintain your active lifestyle.

Basic Nutrition Labs:

Note: There are other labs to assess your medication efficacy and inflammation, but this post will only cover lab values that are influenced by nutrition. Be sure you are actively advocating for your care by keeping your routine annual exams and staying up-to-date with vaccinations.

Complete Blood Count:

These blood tests are used by healthcare professionals to your overall health. The following labs are indirectly related to nutrition but are important to understand in helping manage IBD.

  • Hemoglobin: Hemoglobin is the protein required for transporting oxygen on the red blood cell. A low hemoglobin could be indicative of anemia, and may or may not be related to iron, vitamin B-12, or folate deficiency. 
  • Hematocrit: The volume of red blood cells (RBCs) in the blood is the hematocrit percentage. If there isn’t enough iron in the blood to make enough RBCs, this may be a reason for a low value, but because IBD is a chronic condition, this may be possible even if there is enough iron. 
  • Mean Corpuscular volume (MCV): Measurement of the size of red blood cells. If hematocrit, hemoglobin, and MCV are all low, this could (but may not) indicate iron deficiency anemia. If hematocrit, hemoglobin are both low but the MCV is high, this could indicate vitamin B12 or folate deficiency.
  • Red Blood Cell Count: The number of red blood cells in the blood refers to the red blood cell count. Red blood cells carry oxygenated blood to the body.

Which nutrient-related labs should be checked?

  • Vitamin B-12
  • Folate
  • Iron
  • Vitamin D

Why are these labs important in IBD?

Vitamin B-12 and Folate:

Vitamin B12 and Folate are absorbed in the small intestine, so people with Crohn’s disease with inflammation in the small intestine are at a higher risk of developing deficiencies in these nutrients. Folate levels have been shown to be significantly decreased in patients with IBD, and a decreased serum folate has been suggested to be a risk factor for IBD. Vegans and vegetarians who do not consume eggs and/or yogurt or fortified foods are also at an increased risk for B-12 deficiency. Since many IBD patients avoid dark and leafy-green, folate-rich vegetables, inadequate intake of folate may contribute or exacerbate folate deficiency. Both B-12 and folate are important in many cellular processes, and without sufficient levels, you may experience fatigue, heart palpitations, numbness and tingling, irritability, and vision problems. However, just because you experience these symptoms does not mean you are absolutely deficient; be sure to talk to your doctor about properly diagnosing a deficiency. Maintaining healthy levels of these nutrients is important to ensure proper nutrition status and improving overall health (1).

What to do if you are deficient in folate or B-12? 

Ask your doctor to recommend a supplement with a specific dose amount to fit your individualized needs to correct the deficiency, then ask your doctor when to schedule a lab draw to follow-up with the status of the deficiency. Questions you may want to ask include:

  • “At what dosage and for how long should I take this supplement?”
  • “When should we schedule follow-up labs to re-check these lab values to make sure it’s working?”
  • “What’s the plan if I’m still deficient in folate/vitamin B12 after rechecking the labs?

The vitamin B12 and/or folate deficiency has been corrected! Does that mean you're all clear?

Be vigilant about scheduling B-12 and folate follow-up labs especially if you’ve been deficient in these nutrients in the past. Consider asking your doctor: 

  • “I’d like to stay on top of the levels of checking vitamin B-12/folate since I’ve been deficient in the past….so how frequently should we re-check these labs?”

Normal values for B-12 and/or folate in IBD:

  • Folate: >5.4 ng/dL (2)
  • B-12 in IBD: 200-1100 pg/mL


Iron is important for helping cells function in supporting the central nervous system, the immune system, cardiorespiratory system, vascular system, and the gastrointestinal tract. Iron deficiency is the most frequently observed nutritional obstacle in IBD. Symptoms of iron deficiency can result in fatigue, brittle nails, cold hands and feet, dizziness, shortness of breath, or unusual cravings for non-nutritive substances like ice. If you experience these symptoms, this is not enough evidence to suggest a definitive iron deficiency; always tell your doctor about any symptom you’re experiencing. Iron should be monitored to ensure that the many organ systems that rely on iron can function properly. Iron levels should be monitored to determine if supplementation or infusions are necessary (3). Make sure to ask your doctor how often your iron levels should be checked; this will depend on the severity of your disease and any past medical history of iron deficiency.

Talk to your gastroenterologist about ordering an iron panel and make sure it includes ferritin. An iron panel with ferritin usually includes:

  • Serum iron: The amount of iron in the liquid portion of the blood
  • Transferrin: Transferrin is a protein that moves iron around the body for use. 
  • TIBC (Total Iron-Binding Capacity): Measures the amount of iron that can be bound to proteins. Transferrin is the primary iron-binding protein, but the TIBC test will let clinicians know how much transferrin is available for use
  • UIBC (Unsaturated Iron-Binding Capacity): This measures the amount of transferrin that has not yet been saturated with iron 
  • Transferrin Saturation: Percentage of transferrin that is saturated with iron
  • Serum ferritin: measures the amount of iron stored in the body

Iron Deficiency Anemia:

Although Chart A (shown below) indicates which labs may be altered when iron deficiency anemia is likely to be present (4), always talk to your doctor about your iron panel to find out whether you have iron deficiency anemia, as there are other indications for iron deficiency that may look different from the alterations in labs shown below.

Iron Deficiency labs

Why isn’t serum iron enough?

  • The different forms of iron in the body (e.g. transferrin, the transport form of iron versus ferritin, the storage form of iron) can be influenced by the varying severity of disease that may or may not be present, so it is important to ask for an iron panel for more reliable data points to fully assess iron status. Additionally, different forms of anemias can exist and may be assessed more accurately by looking at iron in all its forms and how it is saturated on red blood cells.

How often should you ask for an iron panel?

Research suggests checking every 3 months if supplementing to correct a deficiency, and every 6 to 12 months after iron deficiency is corrected but always ask your doctor about your specific needs (5). If you’re receiving iron infusions, ask your doctor how often you’ll need to receive them and when you should get your iron rechecked. 

Vitamin D:

Vitamin D is important in maintaining strong bones, helping the gut lining remain intact, and even keeping the immune system in check. Unlike vitamin B-12 or iron deficiency, low vitamin D levels do not often result in symptoms. Low vitamin D (< 40 ng/mL) is more common in people with IBD because of limited exposure to sunlight, possible dietary restrictions, or minimized nutrient absorption from the disease course. Also, since vitamin D is a fat-soluble vitamin, absorption is dependent on the body’s ability to absorb fat and fat-malabsorption is common in patients with IBD. Additionally, vitamin D deficiency is a risk factor for developing IBD. Optimizing vitamin D status has been suggested to decrease the risk of surgery, improve inflammation, decrease the risk of anemia, decrease the risk of colorectal cancer, and improve the body’s response to some medications. There are only a few foods that are good sources of vitamin D some of which include fortified dairy products and non-dairy alternatives, mushrooms exposed to sunlight or UV radiation, and fatty fish (6). If you're not consuming adequate sources of vitamin D, supplementation may be needed. Maintaining adequate serum levels of vitamin D is an important strategy in managing IBD because animal studies suggest it might ameliorate disease progression (7). However, regardless of whether or not it impacts disease activity, it should be a priority to maintain adequate blood levels of vitamin D. 

Have you been on steroids recently? 

Some studies suggest that steroid use could increase the risk for having low blood levels of vitamin D (8). Additionally, studies suggest that vitamin D supplementation can help maintain bone health with long-term steroid use (9). Some questions you may want to ask your physician include:

  • “Since I’m going on this steroid, should I take a vitamin D supplement? And if so, how much should I take?
  • “I’ve been on steroids recently. Would it be a good idea to recheck my serum levels of vitamin D to make sure that my body is still getting what it needs?”

Should you keep taking Vitamin D even if you have normal serum levels?

This is ultimately a question that can be answered by your provider. Reduction in physical activity, alteration in diet, and changes in intestinal absorption all affect vitamin D status in patients with IBD differently, and research studies are looking at whether normal blood levels of vitamin D could reduce the recurrence of flares (10).

  • “I’m encouraged to see that my serum vitamin D is within normal limits. Is there a supplementation dosage that you recommend I keep taking so that I can maintain healthy levels of vitamin D?”


Calcium is an important nutrient that is not easily measured via a blood test since it is stored in the bones. A good way to check on calcium is to get periodic bone density scans, which you can request your doctor to order for you. Be vigilant about eating calcium-fortified foods and/or ask your doctor about whether calcium supplementation is right for you. Also, check back on how to get calcium through your diet even when you’re lactose intolerant in a future post!

Food Sensitivity Testing:

Currently, there are not enough research studies that prove the results of that test are valid and reliable. But, since this is a hot topic I’ll be covering it in depth soon- so stay tuned!

In summary, always ask your doctor questions about your labs so that you can learn more about managing your disease and be an even better advocate for yourself. Staying informed about your labs could mean catching nutrient deficiencies sooner and preventing deficiency symptoms which could greatly improve your overall quality of life.

This information is for educational purposes only. It is not intended to diagnose or treat medical conditions.

Scientific References:

  1. Pan, Y., Liu, Y., Guo, H., Jabir, M. S., Liu, X., Cui, W., & Li, D. (2017). Associations between Folate and Vitamin B12 Levels and Inflammatory Bowel Disease: A Meta-Analysis. Nutrients, 9(4), 382.
  2. Folic Acid: Davis's Lab & Diagnostic Tests. (2020). Nursing Central.
  3. Nielsen, O. H., Soendergaard, C., Vikner, M. E., & Weiss, G. (2018). Rational Management of Iron-Deficiency Anaemia in Inflammatory Bowel Disease. Nutrients, 10(1), 82.
  4. Stein, J., & Dignass, A. U. (2013). Management of iron deficiency anemia in inflammatory bowel disease - a practical approach. Annals of gastroenterology, 26(2), 104–113.
  5. Kilby, K., Mathias, H., Boisvenue, L., Heisler, C., & Jones, J. L. (2019). Micronutrient Absorption and Related Outcomes in People with Inflammatory Bowel Disease: A Review. Nutrients, 11(6), 1388.
  6. Vitamin D Fact Sheet for Health Professionals (2020). National Institutes of Health: Office of Dietary Supplements.
  7. Fletcher, J., Cooper, S. C., Ghosh, S., & Hewison, M. (2019). The Role of Vitamin D in Inflammatory Bowel Disease: Mechanism to Management. Nutrients, 11(5), 1019.
  8. Skversky, A. L., Kumar, J., Abramowitz, M. K., Kaskel, F. J., & Melamed, M. L. (2011). Association of glucocorticoid use and low 25-hydroxyvitamin D levels: results from the National Health and Nutrition Examination Survey (NHANES): 2001-2006. The Journal of clinical endocrinology and metabolism, 96(12), 3838–3845.
  9. Buckley, L. M., Leib, E. S., Cartularo, K. S., Vacek, P. M., Cooper, S. M. (1996). Calcium and Vitamin D3 Supplementation Prevents Bone Loss in the Spine Secondary to Low-Dose Corticosteroids in Patients with Rheumatoid Arthritis. Annals of Internal Medicine, 125(12):961-8.
  10. Ananthakrishnan A. N. (2016). Vitamin D and Inflammatory Bowel Disease. Gastroenterology & hepatology, 12(8), 513–515.

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