Synonym/Acronym
vitamin A: retinol, carotene; vitamin B1: thiamine; vitamin B6: pyroxidine, P-5'-P, pyridoxyl-5-phosphate; vitamin B12: cyanocobalamin; vitamin C: ascorbic acid; vitamin D: cholecalciferol, vitamin D 25-hydroxy, vitamin D 1,25-dihydroxy; vitamin E: alpha-tocopherol; vitamin K: phylloquinone, phytonadione.
Rationale
To assess vitamin deficiency or toxicity to assist in diagnosing nutritional disorders such as malabsorption; disorders that affect vision, blood coagulation, skin, and bones; and other diseases.
Patient Preparation
There are no activity or medication restrictions unless by medical direction. Patient should fast overnight for 12 hr prior to specimen collection for vitamins A, B6, E, and K and should not consume alcohol for 24 hr prior to specimen collection for vitamins A, E, and K.
Normal Findings
Method: High-performance liquid chromatography: vitamins A, B1, B6, C, E, and K; Chemiluminescent immunoassay: vitamin B12 and vitamin D.
| Age | Conventional Units | SI Units |
|---|
| Vitamin A | | (Conventional Units × 0.0349) |
| Birth–1 mo | 14–52 mcg/dL | 0.49–1.81 micromol/L |
| 2 mo–12 yr | 20–49 mcg/dL | 0.7–1.71 micromol/L |
| 13–17 yr | 26–72 mcg/dL | 0.91–2.51 micromol/L |
| 18 yr–Adult | 30–120 mcg/dL | 1.05–4.19 micromol/L |
| Vitamin B1 | | |
| 0.14–0.51 mcg/dL | 4–15 nmol/L |
| Vitamin B6 | | (Conventional Units × 4.046) |
| 5–30 ng/mL | 20–121 nmol/L |
| Vitamin B12 | | (Conventional Units × 0.7378) |
| Adult | 180–914 pg/mL | 132.8–674.3 pmol/L |
| Vitamin C | | (Conventional Units × 56.78) |
| 0.6–1.9 mg/dL | 34.1–107.9 micromol/L |
| Vitamin D 25-hydroxy | | (Conventional Units × 2.496) |
| Deficient | Less than 20 ng/mL | Less than 49.9 nmol/L |
| Insufficient | 20–29 ng/mL | 49.9–72.4 nmol/L |
| Optimal | 30–80 ng/mL | 74.9–199.7 nmol/L |
| Possible toxicity | Greater than 150 ng/mL | Greater than 374.4 nmol/L |
| Vitamin D 1, 25-dihydroxy | | (Conventional Units × 2.6) |
| Adult | 20–80 pg/mL | 52–208 pmol/L |
| Vitamin E | | (Conventional Units × 2.322) |
| Newborn–1 mo | 1–3.5 mg/L | 2.3–8.1 micromol/L |
| 2–5 mo | 2–6 mg/L | 4.6–13.9 micromol/L |
| 6–12 mo | 3.5–8 mg/L | 8.1–18.6 micromol/L |
| 13 mo–12 yr | 5.5–9 mg/L | 12.8–20.9 micromol/L |
| 13 yr–adult | 5–18 mg/L | 11.6–41.8 micromol/L |
| Vitamin K | | Conventional Units × 2.22 |
| Adult | 0.1–2.2 ng/mL | 0.22–4.88 nmol/L |
Vitamin B1, vitamin B6, vitamin B12, and vitamin C levels tend to decrease in older adults. Sustained elevations of vitamin D 25-hydroxy (greater than 50 ng/mL) in conjunction with ongoing calcium supplementation may result in hypercalciuria and decreased renal function.
Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.
Vitamin toxicity can be as significant as problems brought about by vitamin deficiencies. The potential for toxicity is especially important to consider with respect to fat-soluble vitamins (A, D, E, and K), which are not eliminated from the body as quickly as water-soluble vitamins and can accumulate in the body. Most cases of toxicity are brought about by oversupplementing and can be avoided by consulting a registered dietitian for recommended daily dietary and supplemental allowances. Signs and symptoms of vitamin A toxicity may include headache, blurred vision, bone pain, joint pain, dry skin, and loss of appetite. Signs and symptoms of vitamin D toxicity include nausea, loss of appetite, vomiting, polyuria, muscle weakness, and constipation. Excessive supplementation of vitamin E (greater than 60 times the recommended dietary allowance over a period of 1 yr or longer) can result in excessive bleeding, delayed healing of wounds, and depression. The naturally occurring forms vitamins K1 and K2 do not cause toxicity. Signs and symptoms of vitamin K3 toxicity include bleeding and jaundice. Possible interventions include withholding the source.
(Study type: Blood collected in a gold-, red/gray-, green- [sodium or lithium heparin], light green-, green/green gray-, lavender- [EDTA], or pink- [K2 EDTA] top tube for vitamin A and vitamin B1; green-, green/green gray-, red-top tube protected from light at all times for vitamin B6; gold-, red-, red/gray-, light green-, green/green gray-top tube protected from light at all times for vitamin B12; green- [sodium or lithium heparin] top tube protected from light at all times for vitamin C; gold-, red-, red/gray-, green- [lithium heparin], or lavender- [EDTA] top tube for vitamin D 1,25 dihydroxy; gold- or red/gray-top tube for vitamin D 25 hydroxy; gold-, red/gray-, green- [sodium or lithium heparin], lavender- [EDTA], or pink- [K2 EDTA] top tube for vitamin E; and gold-, red-, red/gray-, lavender- [EDTA], or pink- [K2 EDTA] top tube protected from light at all times for vitamin K;related body system: vitamins contribute to multisystem effects.)
Vitamin A, Vitamin B1, Vitamin B6, Vitamin C
Vitamin assays are used in the measurement of nutritional status. Low levels indicate inadequate oral intake, poor nutritional status, or malabsorption problems. High levels indicate excessive intake, vitamin intoxication, or absorption problems. Vitamin A is a fat-soluble nutrient that promotes normal vision and prevents night blindness; contributes to growth of bone, teeth, and soft tissues; supports thyroxine formation; maintains epithelial cell membranes, skin, and mucous membranes; and acts against infection. Vitamins B1, B6, and C are water soluble. Vitamin B1 acts as an enzyme and plays an important role in the Krebs cycle of cellular metabolism. Vitamin B6 is important in heme synthesis and functions as a coenzyme in amino acid metabolism and glycogenolysis. It includes pyridoxine, pyridoxal, and pyridoxamine. Vitamin C promotes collagen synthesis, maintains capillary strength, facilitates release of iron from ferritin to form hemoglobin, and functions in the stress response.
Vitamin B12
Vitamin B12 has a ringed crystalline structure that surrounds an atom of cobalt. It is essential in DNA synthesis, hematopoiesis, and central nervous system (CNS) integrity. It is derived solely from dietary intake. Animal products are the richest source of vitamin B12. Its absorption depends on the presence of intrinsic factor. Circumstances that may result in a deficiency of this vitamin include the presence of stomach or intestinal disease as well as insufficient dietary intake of foods containing vitamin B12. A significant increase in red blood cells (RBCs) means corpuscular volume may be an important indicator of vitamin B12 deficiency.
Vitamin D
Vitamin D is a group of interrelated sterols that have hormonal activity in multiple organs and tissues of the body, including the intestines, kidneys, liver, skin, and bones. Ergocalciferol (vitamin D2) is formed when ergosterol in plants is exposed to sunlight. Ergocalciferol is absorbed by the stomach and intestine when orally ingested. Cholecalciferol (vitamin D3) is formed when the skin is exposed to sunlight or ultraviolet light. Vitamins D2 and D3 enter the bloodstream after absorption. Vitamin D3 is converted to vitamin D 25-hydroxy by the liver and is the major circulating form of the vitamin.Vitamin D2 is converted to vitamin D 1,25-dihydroxy (calcitriol) by the kidneys and is the more biologically active form. Vitamin D is transported throughout the body by albumin and vitamin D binding protein. Activated vitamin D or calcitriol carries out its biological functions by binding to a vitamin D receptor (VDR) in the target cells (bone, intestine, kidney, etc.). One of the better known functions of vitamin D includes regulation of mineral metabolism, mainly calcium and phosphorus. Three feedback loops involving vitamin D (and parathyroid hormone) promote:
- Intestinal absorption of calcium and phosphate (direct effect by activated vitamin D)
- Reabsorption of calcium and excretion of phosphate by the kidney (requires activation of vitamin D by PTH)
- Mobilization of calcium and phosphate stores from bone tissue (requires activation of vitamin D by PTH)
For additional information regarding regulation of calcium levels via feedback cycles involving
calcitonin (a vitamin D antagonist), calcium, parathyroid hormone, and phosphorus, refer to the studies titled “Calcitonin,” “Calcium, Blood, Total and Ionized and Urine,” “Parathyroid Hormone,” and “Phosphorus, Blood and Urine.” The effects of vitamin D deficiency have been studied for many years, and continued research indicates a link between vitamin D deficiency and the development of diseases such as heart failure, stroke, hypertension, cancer, autism, multiple sclerosis, type 2 diabetes, systemic lupus erythematosus, depression, and immune function. The amount of vitamin D
3 produced by exposure of the skin to ultraviolet radiation depends on the intensity of the radiation as well as the duration of exposure. The use of lotions containing sunblock significantly decreases production of vitamin D
3.
Deficiency of this vitamin is very common especially in individuals who avoid exposure to sunlight or in populations:
- living at high altitudes
- living in areas with limited sunlight (e.g., seasonally during winter)
Treatment with over-the-counter vitamin D supplements in conjunction with dosage recommendations made by the HCP are usually sufficient for otherwise healthy individuals. Increased exposure to the sun is another option although use of sunscreen can prevent sufficient sunlight to activate the vitamin to its biologically effective form.
Activated vitamin D is required by a number of important feedback loops in the body. Testing and monitoring are appropriate for high-risk groups with conditions that include:
- chronic kidney disease related to kidney feedback loop
- infections related to immune functions
- malabsorption related to intestinal feedback loop
- osteoporosis related to bone tissue feedback loop
Vitamin E
Vitamin E is a collection of powerful, fat-soluble antioxidants. Alpha-tocopherol appears to be the most plentiful and important form of eight vitamin E antioxidants; there are four tocopherols (alpha-, beta-, gamma-, and delta-) and four tocotrienols (alpha-, beta-, gamma-, and delta-). Antioxidants limit the production of free radicals by preventing the oxidation of unsaturated fatty acids. Free radicals are unstable chemical compounds that contain unshared electrons. They combine rapidly with oxygen during normal metabolic processes in the body when food is converted into energy or when they are taken into the body by environmental exposure from sources such as ultraviolet radiation, air pollution, or secondhand smoke. Vitamin E reserves in lung tissue provide a barrier against air pollution and protect RBC membrane integrity from oxidation. Oxidation of fatty acids in RBC membranes can result in irreversible membrane damage and hemolysis. For many years, scientists have been investigating whether vitamin E might play a role in the amelioration or prevention of chronic and degenerative diseases associated with damage caused by free radicals. Clinical trials, in general, have not provided consistent evidence to support the function of vitamin E as a defense against cardiovascular disease, cataracts, macular degeneration, cancer, and cognitive decline. Studies are currently in progress to further evaluate the potential protective properties of vitamin E. The use of vitamin E as a dietary supplement remains controversial. Current guidelines state that nutrition needs should be met through healthy dietary intake. Because vitamin E is found in a wide variety of foods, a deficiency secondary to inadequate dietary intake is rare. There is research to support the potential interaction between vitamin E and other medications, most notably anticoagulant and antiplatelet drugs. Overuse of supplementary vitamin E has been associated, in some studies, with increased risk of hemorrhagic stroke.
Vitamin K
Vitamin K is one of the fat-soluble vitamins. It is essential for the formation of prothrombin; factors VII, IX, and X; and proteins C and S. Vitamin K also works with vitamin D in synthesizing bone protein and regulating calcium levels. Vitamin K levels are not often requested, but vitamin K is often prescribed as a medication. Levels are considered if the patient has an abnormal INR and does not respond to vitamin K therapy. Approximately one-half of the body’s vitamin K is produced by intestinal bacteria; the other half is obtained from dietary sources. There are three forms of vitamin K: vitamin K1, or phylloquinone, which is found in foods; vitamin K2, or menaquinone, which is synthesized by intestinal bacteria; and vitamin K3, or menadione, which is the synthetic, water-soluble, pharmaceutical form of the vitamin. Vitamin K3 is two to three times more potent than the naturally occurring forms.
Increased In
Vitamin A
- Chronic kidney disease
- Idiopathic hypercalcemia in infants
- Vitamin A toxicity
Vitamin B1:
Vitamin B6:
Vitamin B12
Increases are noted in a number of conditions; pathophysiology is unclear.
- Chronic granulocytic leukemia
- Chronic kidney disease
- Chronic obstructive pulmonary disease (COPD)
- Diabetes
- Leukocytosis
- Liver cell damage (hepatitis, cirrhosis) (stores in damaged hepatocytes are released into circulation; synthesis of transport proteins is diminished by liver damage)
- Obesity
- Polycythemia vera
- Protein malnutrition (lack of transport proteins increases circulating levels)
- Severe heart failure
- Some cancers
Vitamin D
- Endogenous vitamin D intoxication (in conditions such as sarcoidosis, cat scratch disease, and some lymphomas, extrarenal conversion of 25-hydroxy to 1,25-dihydroxy vitamin D occurs with a corresponding abnormal elevation of calcium)
- Exogenous vitamin D intoxication
Vitamin E
- Obstructive liver disease (related to malabsorption associated with obstructive liver disease)
- Vitamin E intoxication (related to excessive intake)
Vitamin K
- Excessive administration of vitamin K
Decreased In
Vitamin A
- Abetalipoproteinemia (related to poor absorption)
- Carcinoid syndrome (related to poor absorption)
- Chronic infections (vitamin A deficiency decreases ability to fight infection)
- Cystic fibrosis (related to poor absorption)
- Disseminated tuberculosis (related to poor absorption)
- Hypothyroidism (condition decreases ability of beta carotene to convert to vitamin A)
- Infantile blindness (related to dietary deficiency)
- Liver, gastrointestinal, or pancreatic disease (related to malabsorption or poor absorption)
- Night blindness (related to chronic dietary deficiency or lack of absorption)
- Protein malnutrition (related to dietary deficiency)
- Sterility and teratogenesis (related to dietary deficiency)
- Zinc deficiency (zinc is required for generation of vitamin A transport proteins)
Vitamin B1
- Carcinoid syndrome (related to dietary deficiency or lack of absorption)
- Hartnup disease (related to dietary deficiency)
- Pellagra (related to dietary deficiency)
- Substance use disorder—alcohol (related to dietary deficiency)
Vitamin B6
(This vitamin is involved in many essential functions, such as nucleic acid synthesis, enzyme activation, antibody production, electrolyte balance, and RBC formation; deficiencies result in a variety of conditions.)
- Asthma
- Carpal tunnel syndrome
- Gestational diabetes
- Kidney dialysis
- Lactation (related to dietary deficiency and/or increased demand)
- Malabsorption
- Malnutrition
- Neonatal seizures
- Normal pregnancies (related to dietary deficiency and/or increased demand)
- Occupational exposure to hydrazine compounds (enzymatic pathways are altered by hydralazines in a manner that increases excretion of vitamin B6)
- Pellagra (related to dietary deficiency)
- Pre-eclamptic edema
- Substance use disorder—alcohol (related to dietary deficiency)
- Uremia
Vitamin B12
- Abnormalities of cobalamin transport or metabolism
- Bacterial overgrowth (vitamin is consumed and utilized by the bacteria)
- Crohn disease (related to poor absorption)
- Dietary deficiency (related to insufficient intake, e.g., in vegetarians)
- Diphyllobothrium (fish tapeworm) infestation (vitamin is consumed and utilized by the parasite)
- Gastric or small intestine surgery (related to dietary deficiency or poor absorption)
- Hypochlorhydria (related to ineffective digestion resulting in poor absorption)
- Inflammatory bowel disease (related to dietary deficiency or poor absorption)
- Intestinal malabsorption
- Intrinsic factor deficiency (required for proper vitamin B12 absorption)
- Late pregnancy (related to dietary deficiency or poor absorption)
- Pernicious anemia (related to dietary deficiency or poor absorption)
Vitamin C
- Anemia (related to dietary deficiency)
- Cancer (related to dietary deficiency or lack of absorption)
- Hemodialysis (vitamin C is lost during the treatment)
- Hyperthyroidism (related to dietary deficiency and/or increased demand)
- Kidney dialysis (vitamin C is lost during the treatment)
- Malabsorption
- Pregnancy (related to dietary deficiency and/or increased demand)
- Rheumatoid disease
- Scurvy (related to dietary deficiency or lack of absorption)
- Substance use disorder—alcohol (related to dietary deficiency)
Vitamin D
- Bowel resection (related to lack of absorption)
- Celiac disease (related to lack of absorption)
- Inflammatory bowel disease (related to lack of absorption)
- Malabsorption (related to lack of absorption)
- Osteomalacia (related to dietary insufficiency)
- Osteoporosis (related to dietary insufficiency or lack of sunlight)
- Pancreatic insufficiency (lack of digestive enzymes to metabolize fat-soluble vitamin D; malabsorption)
- Rickets (related to dietary insufficiency)
- Thyrotoxicosis (possibly related to increased calcium loss through sweat, urine, or feces with corresponding decrease in vitamin D levels)
Vitamin E
- Abetalipoproteinemia (rare inherited disorder of fat metabolism evidenced by poor absorption of fat and fat-soluble vitamin E)
- Hemolytic anemia (related to deficiency of vitamin E, an important antioxidant that protects RBC membranes from weakening)
- Malabsorption disorders, such as biliary atresia, cirrhosis, cystic fibrosis, chronic pancreatitis, pancreatic cancer, and chronic cholestasis
Vitamin K
- Antibiotic therapy (related to decreased intestinal flora)
- Chronic fat malabsorption (related to lack of digestive enzymes and poor absorption)
- Cystic fibrosis (related to lack of digestive enzymes and poor absorption)
- Diarrhea (in infants) (related to increased loss in feces)
- Gastrointestinal disease (related to malabsorption)
- Hemorrhagic disease of the newborn (newborns normally have low levels of vitamin K; neonates at risk are those who are not given a prophylactic vitamin K shot at birth or those receiving nutrition strictly from human milk, which has less vitamin K than cow’s milk)
- Hypoprothrombinemia (related to insufficient levels of prothrombin, a vitamin K–dependent protein)
- Liver disease (interferes with storage of vitamin K)
- Obstructive jaundice (related to insufficient levels of bile salts required for absorption of vitamin K)
- Pancreatic disease (related to insufficient levels of enzymes to metabolize vitamin K)
Before the Study: Planning and Implementation
Teaching the Patient What to Expect
- Explain that a blood sample is needed for the test.
- Discuss how this test can assist in diagnosing a vitamin toxicity or deficiency.
After the Study: Implementation & Evaluation Potential Nursing Actions
Treatment Considerations
- Interventions/actions include the following: Provide information on specific deficiency and any lifestyle implications. Be aware that some deficiencies are linked to physical changes and emotional distress.
Nutritional Considerations
General
- Interventions/actions include the following: Determine the patient’s ability to select appropriate vitamin-rich foods. Facilitate a dietary consult focused on appropriate culturally congruent nutritional choices. Evaluate all supplements and dietary choices in relation to the patient’s clinical condition or health concerns. Collaborate with the HCP in determining the need for vitamin supplements.
Vitamin A
- Interventions/actions include the following: Explain to those with a deficiency that the main dietary source of vitamin A is carotene, a yellow pigment noticeable in most fruits and vegetables, most specifically in carrots, sweet potatoes, squash, apricots, and cantaloupe. Note that carotene is also present in spinach, collards, broccoli, and cabbage. Explaing that vitamin A is fairly stable at most cooking temperatures, but it is destroyed easily by light and exposure to air.
Vitamin B1
- Interventions/actions include the following: Explain that vitamin B1 is the most stable with respect to the effects of environmental factors. Discuss with the vitamin B1–deficient patient the main dietary sources of vitamin B1, which are meats, coffee, peanuts, and legumes. Discuss how the body is also capable of making some vitamin B1 by converting the amino acid tryptophan to niacin.
Vitamin B6
- Interventions/actions include the following: Discuss with those having a vitamin B6 deficiency that the main dietary sources of vitamin B6 include meats (especially beef and pork), whole grains, wheat germ, legumes (beans, peas, lentils), potatoes, oatmeal, and bananas. Vitamin B6, as with other water-soluble vitamins, is best preserved by rapid cooking. Advise that Vitamin B6 is rapidly destroyed by light.
Vitamin B12
- Interventions/actions include the following: Advise the patient with vitamin B12 deficiency in the use of vitamin supplements. Explain that the best dietary sources of vitamin B12 are meats, fish, poultry, eggs, and milk.
Vitamin C
- Interventions/actions include the following: Educate those with vitamin C deficiency that citrus fruits are excellent dietary sources of vitamin C. Inform that additional sources of vitamin C are green and red peppers, tomatoes, white potatoes, cabbage, broccoli, chard, kale, turnip greens, asparagus, berries, melons, pineapple, and guava. Explain that vitamin C is destroyed by exposure to air, light, or heat. Inform that boiling water before cooking eliminates dissolved oxygen that destroys vitamin C in the process of boiling. Vegetables should be crisp and cooked as quickly as possible.
Vitamin D
- Interventions/actions include the following: Explain to those having a vitamin D deficiency that foods high in calcium and vitamin D should be included in the diet. Examples of foods rich in calcium and vitamin D are yogurt, cheese, cottage cheese, canned sardines with bones, flounder, salmon, dried figs, and dark green leafy vegetables such as spinach and broccoli. Processed foods with added calcium, such as breads and cereals, can also be included in the diet. Advise that excess use of alcohol, salt, or caffeine can decrease absorption. Explain that vitamin D is also synthesized by the body, in the skin, and is activated by sunlight. Daily recommendations for calcium and vitamin D intake are based on age.
Vitamin E
- Interventions/actions include the following: Advise those with a vitamin E deficiency that the main dietary sources of vitamin E are vegetable oils (including olive oil), whole grains, fortified cereals, wheat germ, nuts, seeds, soy products, milk (fat-free or low-fat milk and milk products), eggs, seafood, meats, fish, fruits, and vegetables, especially legumes and green leafy vegetables. Vitamin E is fairly stable at most cooking temperatures with the exception of frying.
Vitamin K
- Interventions/actions include the following: Advise those with a vitamin K deficiency that the main dietary sources of vitamin K are broccoli, cabbage, cauliflower, kale, spinach, leaf lettuce, watercress, parsley, and other raw green leafy vegetables, pork, liver, soybeans, mayonnaise, and vegetable oils.
Clinical Judgement
- Consider how to emphasize the risk to health by either vitamin misuse or neglect.
Follow-Up Evaluation and Desired Outcomes
General
- Acknowledges contact information provided for the U.S. Department of Agriculture’s resource for nutrition (www.myplate.gov).
- Those with a specific vitamin deficiency recognize the value of dietary sources of these vitamins and will consider asking a registered dietitian to assist in the development of a diet plan to meet specific needs.
Vitamin D
Vitamin K
- Acknowledges the importance of reporting bleeding from any areas of the skin or mucous membranes.
- Acknowledges the importance of taking precautions against bleeding or bruising, including the use of a soft-bristle toothbrush, use of an electric razor, avoidance of constipation, avoidance of aspirin products, and avoidance of intramuscular injections.