Do You Need a Vitamin A Deficiency Test? Consider This First

Do You Need a Vitamin A Deficiency Test? Consider This First

Important Considerations Before a Vitamin A Deficiency Test

Vitamin A deficiency is rare, but if you’re experiencing symptoms such as bumps on the back of your arms, dry eyes, night blindness, and getting sick often, an inexpensive blood test can reliably detect this vitamin deficiency. 

However, serum vitamin A levels remain normal on a test until a severe deficiency occurs, so a vitamin A deficiency test is generally unnecessary if you are healthy and don’t have any of the symptoms of vitamin A deficiency. 

In this article, we’ll break down what you need to know about vitamin A including what it is, possible signs and symptoms of a deficiency, available vitamin A deficiency test options, factors that can affect your vitamin A level, and supplementation.

Doctor doing a vitamin A deficiency test

Vitamin A Testing

A vitamin A deficiency test is unnecessary for most healthy adults and young children for a couple of reasons:

  • Vitamin A deficiency is rare in developed countries.
  • Unless you are already severely deficient, a serum vitamin A lab test probably won’t give an accurate picture of your vitamin A status because it tests levels in your blood, not your liver. 50%-85% of your vitamin A is stored in the liver. Serum vitamin A levels in healthy people remain pretty constant until liver reserves are severely depleted [1 Trusted SourcePubMedGo to source, 2 Trusted SourcePubMedGo to source].

However, a vitamin A deficiency test may be helpful  if:

  • You are at high risk (I’ll talk about this later)
  • You have deficiency symptoms
  • Your physician suspects a deficiency

If you need to test your vitamin A levels, a serum (blood) retinol (vitamin A) test is the most reliable and practical test for vitamin A deficiency. This vitamin A deficiency test correlates closely with the prevalence and severity of xerophthalmia (dry eye) and may change with supplementation [3 Trusted SourcePubMedGo to source].  

Serum retinol can be assessed by using two different lab methods called  high-performance liquid chromatography (HPLC) and spectrophotometry. The latter is more simple and less expensive, but HPLC is still usually less than 40 dollars, is more accurate, and is the preferred method.

There is generally no need for any other kind of specialized testing, which can be expensive and less accessible. These other tests may include:

A serum vitamin A level of 58.3 micrograms per deciliter (mcg/dL) may be optimal. If your level has fallen below 20 mcg/dL, your liver stores are already severely depleted and you will need to begin supplementation as soon as possible under the advice of your health care provider [5 Trusted SourcePubMedGo to source].

Vitamin A and Where You Can Find It

Vitamin A deficiency test: Vitamin A-rich foods

Vitamin A refers to a group of compounds. The forms of vitamin A include retinol, retinoic acid, retinal, and provitamin A carotenoids. Vitamin A is important for proper immune function, cell growth and repair, bone growth, reproduction, and normal embryonic and fetal development [6].

Since it can’t be created by the body, vitamin A is an essential nutrient. This means you need to get it through your diet or supplements. There are a variety of plant and animal sources. 

Preformed vitamin A (retinol or retinoic acid) can be found in [3 Trusted SourcePubMedGo to source]: 

  • Breast milk
  • Liver
  • Cod liver oil
  • Dairy products
  •  Egg yolks 

Provitamin A carotenoids (beta-carotene) are found in plant foods [3 Trusted SourcePubMedGo to source]:

  • Dark green leafy vegetables
  • Deeply colored yellow and orange vegetables and fruit

Who Is at Risk of Vitamin A Deficiency?

Vitamin A deficiency is rare in developed countries, but researchers in one study of bariatric (weight loss) surgery patients reported this vitamin deficiency in up to 69% of the study group [7 Trusted SourcePubMedGo to source]. Weight loss surgery is designed to induce weight reduction, but in the process can create nutrient malabsorption.

 Other high-risk populations include:  

  • Preterm infants
  • Infants with vitamin A-deficient mothers
  • Those with gastrointestinal malabsorption:
    • Celiac disease (an autoimmune disease where the body reacts strongly to gluten)
    • Short bowel syndrome (poor absorption of nutrients)
    • Exocrine pancreatic insufficiency (lack of adequate digestive enzymes from the pancreas)
    • Crohn’s disease (inflammation in the digestive tract)
  • Alcoholics and those with non-alcoholic fatty liver disease
  • Those consuming a diet that’s very low in fat 
  • Those with malnutrition or inadequate nutrient intake

What Are the Signs and Symptoms of Vitamin A Deficiency?

Vitamin A deficiency is known to cause xerophthalmia, a form of dry eye affecting the retina and cornea causing low vision in dim light or blindness. But, low vitamin A can also impair your immune system function [3 Trusted SourcePubMedGo to source]. Common signs and symptoms include:

  • Bumps on the back of the arms
  • Recurrent infections and poor immune system function
  • Dry eyes
  • Night blindness
  • Bitot’s spots (the buildup of protein on the eye) 

Lesser-known signs and symptoms may include:

A severe deficiency of vitamin A can lead to blindness, but this is extremely rare.

If you are experiencing the signs and symptoms of vitamin A deficiency and you are at high risk, it is generally safe to supplement with a modest dose of vitamin A without testing. 

While on the supplement, you should monitor your symptoms for improvement. But it really makes the most sense to test before adding a supplement. A vitamin A deficiency test is inexpensive and fairly accurate in cases of severe deficiency.

Other Deficiencies and Imbalances Can Affect Your Vitamin A Levels

So, why is your serum vitamin A level not responding to vitamin A-rich foods and vitamin A supplementation? Certain micronutrient deficiencies and health considerations may be at play:

  • Zinc deficiency can affect the absorption, transport, and utilization of vitamin A [9 Trusted SourcePubMedGo to source].
  • Iron deficiency may negatively impact serum retinol concentrations and decrease vitamin A mobilization from the liver [2 Trusted SourcePubMedGo to source].
  • Low dietary protein intake can falsely lower serum retinol levels [10].
  • Inflammation and infection can force serum retinol levels to decline due to a decrease in retinol binding protein [3 Trusted SourcePubMedGo to source].

If you have a low vitamin A level, it’s important to work with your practitioner to uncover and correct underlying factors.

When Are Vitamin A Supplements Helpful?

Supplements on a wooden spoon

In cases of deficiency, vitamin A supplementation may be helpful for several conditions:

  • Immune system function: In areas where vitamin A deficiency is a public health concern, high-dose vitamin A supplements decrease the risk of childhood measles in kids ages six months to five years [3 Trusted SourcePubMedGo to source].
  • Post-infectious loss of smell: One study found 10,000 international units (IU) of intranasal vitamin A improved sense of smell after eight weeks when compared to controls [11 Trusted SourcePubMedGo to source]. However, the same dose of vitamin A in oral form did not improve olfactory function significantly compared to the control group [12 Trusted SourcePubMedGo to source].
  • Dry eye disease: Oral supplementation of 1,500 milligrams (mg) of oral vitamin A for three consecutive days has been shown to improve tear quality test results in patients with dry eye disease [13 Trusted SourcePubMedGo to source].
  • Skin disorders: Topical and systemic use of vitamin A and its derivatives may be beneficial for acne, psoriasis, keratosis pilaris (tiny bumps and dry rough patches), skin cancer, and ichthyosis (a genetic disorder causing dry, scaly skin) [14 Trusted SourcePubMedGo to source, 15 Trusted SourcePubMedGo to source].
  • Hypothyroidism: In children with both iodine and vitamin A deficiency, vitamin A supplementation along with iodized salt improved thyroid markers and decreased the risk of hypothyroidism [16 Trusted SourcePubMedGo to source]. 
  • Parkinson’s disease: PD patients who took a combination supplement that included vitamin A for 30 months experienced significantly delayed disease progression compared to controls [17 Trusted SourcePubMedGo to source].
  • Multiple sclerosis: MS patients receiving 25,000 IU/day of retinyl palmitate for six months followed by 10,000 IU/day retinyl palmitate for another six months experienced significant reductions in depression and fatigue [18 Trusted SourcePubMedGo to source].

Vitamin A and beta carotene supplementation may not be helpful and may be harmful in these conditions:

  • Cancer: People with higher intakes of vitamin A and beta carotene-rich foods have lower lung cancer risk. However, in one study of smokers and asbestos-exposed individuals, high doses of supplemental beta-carotene and vitamin A were associated with increased lung cancer risk when compared to controls who took no vitamins [19 Trusted SourcePubMedGo to source, 20 Trusted SourcePubMedGo to source]. Increased prostate cancer risk may exist in those with higher circulating levels of carotenoids and retinol [21 Trusted SourcePubMedGo to source, 22 Trusted SourcePubMedGo to source].
  • Atherosclerosis (hardening of the arteries): In smokers and asbestos-exposed individuals, supplementation with 25,000 IU vitamin A plus 30 mg of beta carotene was associated with a slight increased risk of atherosclerosis. However, the result was not statistically significant [20 Trusted SourcePubMedGo to source].

Vitamin A Supplementation Guide and Considerations

The Ancient Egyptians and Greeks cured night blindness with vitamin A-rich roasted oxen liver as early as 460 to 325 BC [3 Trusted SourcePubMedGo to source]. Correcting a vitamin A deficiency today can also be accomplished by consuming vitamin A-rich foods, but supplemental beta-carotene and preformed retinol are available as well. 

The daily recommended dietary allowance (RDA) in retinol equivalents is 900 micrograms (mcg) per day or 3,000 IU for adult men and 700 mcg per day or 2,300 IU for adult women [6]. The daily tolerable upper intake level (UL) for adults is set at 3,000 mcg of preformed (animal-based) vitamin A [6].

Taking supplemental vitamin A with other fat-soluble vitamins like vitamins D, E, and K is probably the best practice. Large doses of vitamin A may negatively affect the status of other nutrients. One study found breast-feeding mothers who received 200,000 IU of retinyl palmitate after the first colostrum collection had decreased bioavailability of vitamin E in their breast milk [23 Trusted SourcePubMedGo to source].

Those with the following conditions may require higher doses of these fat-soluble vitamins:

  • Exocrine pancreatic insufficiency (lack of adequate digestive enzymes leads to the inability to digest food properly)
  • Cholestasis (a liver disease where the flow of bile is reduced or blocked)
  • Weight loss surgery
  • Crohn’s disease 
  • Celiac disease
  • Other malabsorption disorders of the intestine

Caution with supplemental vitamin A during pregnancy is recommended due to the potential for birth defects. Even though most related birth defects have been linked to women taking greater than 25,000 IU vitamin A per day, pregnant women should not exceed 10,000 IU vitamin A per day [24 Trusted SourcePubMedGo to source]. 

If your test results indicate you are vitamin A deficient, work with your healthcare provider to determine your specific supplementation needs. 

Can Supplementation Lead to Vitamin A Toxicity? (Hypervitaminosis A)

A standard supplemental dose of vitamin A is not at all likely to lead to toxicity, especially if you have a suspected or confirmed deficiency. 

Vitamin A is a fat-soluble vitamin meaning it can be stored in the body for long periods, so theoretically, it can become toxic. However, toxicity from over-supplementing with vitamin A is unlikely and is usually the result of extremely high doses (greater than 10 times the RDA) of this vitamin over the course of months to years. 

Vitamin A toxicity symptoms and concerns include:  

Serum retinol testing is not accurate for detecting vitamin A toxicity. Since most of your vitamin A is stored in the liver, serum levels can appear normal or even low despite very high liver levels.

If you suspect or are concerned about a toxicity, seek medical attention. But again, vitamin A toxicity is not common and if you’re taking supplemental vitamin A under the care of your healthcare provider, there is generally no need for concern. 

Vitamin A Deficiency May Indicate a Larger Issue

Vitamin A deficiency is rare, but if you are in the high-risk category or have vitamin A deficiency symptoms, you may want to test your serum vitamin A level.

If you’re below the recommended level, improving your vitamin A status is generally easily accomplished by increasing your intake of vitamin A food sources. However, modest supplementation is also safe and effective. 

Continued low serum vitamin A levels despite supplementation may be indicative of a larger issue. For more guidance, schedule an appointment with the Ruscio Institute of Functional Medicine. 

➕ References
  1. Green MH, Green JB, Berg T, Norum KR, Blomhoff R. Changes in hepatic parenchymal and nonparenchymal cell vitamin A content during vitamin A depletion in the rat. J Nutr. 1988 Nov;118(11):1331–5. DOI: 10.1093/jn/118.11.1331. PMID: 3193250. Trusted SourcePubMedGo to source
  2. Tanumihardjo SA. Assessing vitamin A status: past, present and future. J Nutr. 2004 Jan;134(1):290S-293S. DOI: 10.1093/jn/134.1.290S. PMID: 14704336. Trusted SourcePubMedGo to source
  3. Tanumihardjo SA, Russell RM, Stephensen CB, Gannon BM, Craft NE, Haskell MJ, et al. Biomarkers of Nutrition for Development (BOND)-Vitamin A Review. J Nutr. 2016 Sep;146(9):1816S-48S. DOI: 10.3945/jn.115.229708. PMID: 27511929. PMCID: PMC4997277. Trusted SourcePubMedGo to source
  4. da Silva Pereira A, da Silva ACF, Bezerra FF, Citelli M, Nogueira Neto JF, de Castro IRR. Reproducibility and validity of capillary dried blood spot for diagnosis of vitamin A deficiency and anemia in children <5 years old. J Nutr. 2021 Oct 1;151(10):3197–204. DOI: 10.1093/jn/nxab226. PMID: 34293140. Trusted SourcePubMedGo to source
  5. Li H, He P, Lin T, Guo H, Li Y, Song Y, et al. Association between plasma retinol levels and the risk of all-cause mortality in general hypertensive patients: A nested case-control study. J Clin Hypertens (Greenwich). 2020 May;22(5):906–13. DOI: 10.1111/jch.13866. PMID: 32352642. PMCID: PMC8030112. Trusted SourcePubMedGo to source
  6. Centers for Disease Control and Prevention. Second National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population: Fat Soluble Vitamins and Nutrients [Internet]. Fat Soluble Vitamins and Nutrients. [cited 2022 Jan 13]. Available from:
  7. Slater GH, Ren CJ, Siegel N, Williams T, Barr D, Wolfe B, et al. Serum fat-soluble vitamin deficiency and abnormal calcium metabolism after malabsorptive bariatric surgery. J Gastrointest Surg. 2004 Jan;8(1):48–55; discussion 54. DOI: 10.1016/j.gassur.2003.09.020. PMID: 14746835. Trusted SourcePubMedGo to source
  8. Wen J, Yang T, Zhu J, Guo M, Lai X, Tang T, et al. Vitamin a deficiency and sleep disturbances related to autism symptoms in children with autism spectrum disorder: a cross-sectional study. BMC Pediatr. 2021 Jul 3;21(1):299. DOI: 10.1186/s12887-021-02775-0. PMID: 34217246. PMCID: PMC8254303. Trusted SourcePubMedGo to source
  9. Christian P, West KP. Interactions between zinc and vitamin A: an update. Am J Clin Nutr. 1998 Aug;68(2 Suppl):435S-441S. DOI: 10.1093/ajcn/68.2.435S. PMID: 9701158. Trusted SourcePubMedGo to source
  10. Institute of Medicine (US) Panel on Micronutrients. Iron – Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc – NCBI Bookshelf. Available from:
  11. Hummel T, Whitcroft KL, Rueter G, Haehner A. Intranasal vitamin A is beneficial in post-infectious olfactory loss. Eur Arch Otorhinolaryngol. 2017 Jul;274(7):2819–25. DOI: 10.1007/s00405-017-4576-x. PMID: 28434127. Trusted SourcePubMedGo to source
  12. Reden J, Lill K, Zahnert T, Haehner A, Hummel T. Olfactory function in patients with postinfectious and posttraumatic smell disorders before and after treatment with vitamin A: a double-blind, placebo-controlled, randomized clinical trial. Laryngoscope. 2012 Sep;122(9):1906–9. DOI: 10.1002/lary.23405. PMID: 22752966. Trusted SourcePubMedGo to source
  13. Alanazi SA, El-Hiti GA, Al-Baloud AA, Alfarhan MI, Al-Shahrani A, Albakri AA, et al. Effects of short-term oral vitamin A supplementation on the ocular tear film in patients with dry eye. Clin Ophthalmol. 2019 Apr 10;13:599–604. DOI: 10.2147/OPTH.S198349. PMID: 31040640. PMCID: PMC6462169. Trusted SourcePubMedGo to source
  14. Orfanos CE, Zouboulis CC, Almond-Roesler B, Geilen CC. Current use and future potential role of retinoids in dermatology. Drugs. 1997 Mar;53(3):358–88. DOI: 10.2165/00003495-199753030-00003. PMID: 9074840. Trusted SourcePubMedGo to source
  15. Szymański Ł, Skopek R, Palusińska M, Schenk T, Stengel S, Lewicki S, et al. Retinoic acid and its derivatives in skin. Cells. 2020 Dec 11;9(12). DOI: 10.3390/cells9122660. PMID: 33322246. PMCID: PMC7764495. Trusted SourcePubMedGo to source
  16. Zimmermann MB, Wegmüller R, Zeder C, Chaouki N, Torresani T. The effects of vitamin A deficiency and vitamin A supplementation on thyroid function in goitrous children. J Clin Endocrinol Metab. 2004 Nov;89(11):5441–7. DOI: 10.1210/jc.2004-0862. PMID: 15531495. Trusted SourcePubMedGo to source
  17. Pantzaris M, Loukaides G, Paraskevis D, Kostaki E-G, Patrikios I. Neuroaspis PLP10TM, a nutritional formula rich in omega-3 and omega-6 fatty acids with antioxidant vitamins including gamma-tocopherol in early Parkinson’s disease: A randomized, double-blind, placebo-controlled trial. Clin Neurol Neurosurg. 2021 Nov;210:106954. DOI: 10.1016/j.clineuro.2021.106954. PMID: 34607196. Trusted SourcePubMedGo to source
  18. Bitarafan S, Saboor-Yaraghi A, Sahraian M-A, Soltani D, Nafissi S, Togha M, et al. Effect of Vitamin A Supplementation on fatigue and depression in Multiple Sclerosis patients: A Double-Blind Placebo-Controlled Clinical Trial. Iran J Allergy Asthma Immunol. 2016 Feb;15(1):13–9. PMID: 26996107. Trusted SourcePubMedGo to source
  19. Yu N, Su X, Wang Z, Dai B, Kang J. Association of Dietary Vitamin A and β-Carotene Intake with the Risk of Lung Cancer: A Meta-Analysis of 19 Publications. Nutrients. 2015 Nov 11;7(11):9309–24. DOI: 10.3390/nu7115463. PMID: 26569298. PMCID: PMC4663591. Trusted SourcePubMedGo to source
  20. Omenn GS, Goodman GE, Thornquist MD, Balmes J, Cullen MR, Glass A, et al. Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. N Engl J Med. 1996 May 2;334(18):1150–5. DOI: 10.1056/NEJM199605023341802. PMID: 8602180. Trusted SourcePubMedGo to source
  21. Nash SH, Till C, Song X, Lucia MS, Parnes HL, Thompson IM, et al. Serum Retinol and Carotenoid Concentrations and Prostate Cancer Risk: Results from the Prostate Cancer Prevention Trial. Cancer Epidemiol Biomarkers Prev. 2015 Oct;24(10):1507–15. DOI: 10.1158/1055-9965.EPI-15-0394. PMID: 26269564. PMCID: PMC4592455. Trusted SourcePubMedGo to source
  22. Key TJ, Appleby PN, Travis RC, Albanes D, Alberg AJ, Barricarte A, et al. Carotenoids, retinol, tocopherols, and prostate cancer risk: pooled analysis of 15 studies. Am J Clin Nutr. 2015 Nov;102(5):1142–57. DOI: 10.3945/ajcn.115.114306. PMID: 26447150. PMCID: PMC4625592. Trusted SourcePubMedGo to source
  23. Grilo EC, Medeiros WF, Silva AGA, Gurgel CSS, Ramalho HMM, Dimenstein R. Maternal supplementation with a megadose of vitamin A reduces colostrum level of α-tocopherol: a randomised controlled trial. J Hum Nutr Diet. 2016 May 27;29(5):652–61. DOI: 10.1111/jhn.12381. PMID: 27231056. Trusted SourcePubMedGo to source
  24. Biesalski HK. Comparative assessment of the toxicology of vitamin A and retinoids in man. Toxicology. 1989 Jul 17;57(2):117–61. DOI: 10.1016/0300-483X(89)90161-3. PMID: 2665185. Trusted SourcePubMedGo to source
  25. Toraishi M, Uenishi K, Iwamoto J, Otani T. Vitamin A intake is related to stress fracture occurrence in male collegiate long-distance runners. J Sports Med Phys Fitness. 2021 Nov;61(11):1509–14. DOI: 10.23736/S0022-4707.20.11792-4. PMID: 33269888. Trusted SourcePubMedGo to source

Need help or would like to learn more?
View Dr. Ruscio’s additional resources

Get Help


I care about answering your questions and sharing my knowledge with you. Leave a comment or connect with me on social media asking any health question you may have and I just might incorporate it into our next listener questions podcast episode just for you!

Leave a Reply

Your email address will not be published. Required fields are marked *