Vitamins

Indications for Testing

Vitamin B₁₂ – patients at risk
- Malabsorption, use of H₂ receptor antagonists, proton-pump inhibitors, vegetarian diet
Vitamin D – patients at risk
- Poor nutritional intake, limited sun exposure, malabsorption. liver failure, or renal insufficiency
- Aged adults and patients taking antiseizure medicine
Other vitamins – symptoms consistent with deficiency and risk for deficiency

Laboratory Testing

Order specific testing based on symptoms
For B₁₂ deficiency – concurrent folate level testing recommended; refer to the following for more information
For vitamin D deficiency – order 25-hydroxy vitamin D by chemiluminescence, if available
- 20-30 ng/mL – defined as insufficiency
- <20 mg/ng/mL – defined as deficiency
- Do not order 1,25-dihydroxy testing; fractionation testing for D₂ and D₃ not necessary for initial evaluation of vitamin D deficiency

Consider deficiency screening for patients at risk – use 25-hydroxy vitamin D test
- Institutionalized refugees
- Celiac disease
- Patients with osteoporosis
- Patients from areas with high vitamin D deficiency
- Older adults due to known risks of deficiency

Vitamin D₂ or D₃ therapy recommended for deficient patients
- Monitor therapy with 25-hydroxy vitamin D
- Patients who do not appear to be responding to therapy – vitamin D₂ or D₃ testing may be helpful

Vitamins are required in the diet because they are not adequately synthesized in the human body.

Only small amounts are necessary to catalyze essential biochemical reactions
Most deficiencies are rare in healthy persons in the U.S.
- Exceptions for vitamins B₁₂ and D
- Exceptions in gastric bypass patients, celiac disease patients, alcoholics, and persons with inadequate nutrition (eg, the elderly) or malabsorptive defects
Disease states generally result from poor diet
Body stores vary by vitamin
- Thiamine (B₁) and folate stores are small and rapidly depleted
- Cobalamin (B₁₂) stores are large
Vitamins play several roles in disease processes
- Diseases can cause vitamin deficiency
- Vitamin deficiency or excess can cause disease
- High doses of certain vitamins can be used to manage some diseases
  - Niacin – hyperlipidemia
  - Vitamin D – osteoporosis
  - Pyridoxine – treatment of first trimester nausea
  - Folate – prevention of neural tube defect

Water soluble vitamins

Water Soluble Vitamins
Vitamin	Disease States
B₁ (thiamine) Catalyzes reactions that produce energy Sources – legumes, nuts, whole grains Inhibitors – alcohol, coffee, loop diuretics, raw fish, shellfish, tea	Vitamin B₁ deficiency Mainly found in alcoholics in U.S. Wet beriberi – high-output cardiac failure Dry beriberi – symmetrical peripheral neuropathy Wernicke encephalopathy – beriberi combined with alcoholism; horizontal nystagmus, ophthalmoplegia, cerebellar ataxia, mental impairment Wernicke-Korsakoff syndrome – coexistence of additional loss of memory and confabulatory psychosis Vitamin B₁ toxicity – rare reports of anaphylaxis
B₂ (riboflavin) Catalyzes reactions that produce energy; coenzyme in the flavoproteins that participate in tissue oxidation and respiration processes Sources – broccoli, eggs, enriched breads, fish, lean meats, legumes, milk, other dairy products Inhibitors – sunlight rapidly degrades the vitamin in foodstuffs	Vitamin B₂ deficiency Mucocutaneous lesions including magenta tongue, angular stomatosis, seborrhea, cheilosis Vitamin B₂ toxicity None reported; gastrointestinal tract can only absorb limited quantities
B₃ (niacin) Catalyzes the metabolism of fatty acids, amino acids and carbohydrates Sources – beans, eggs, meat, milk Inhibitors – B₂ or B₆ deficiency reduces conversion of tryptophan to niacin; drugs that may interfere with metabolism include alcohol, amitriptyline, chlorpromazine, imipramine	Vitamin B₃ deficiency Mainly found in alcoholics in U.S. Can occur in carcinoid and Hartnup diseases Pellagra – pigmented rash in sun-exposed areas (Casal necklace), bright red tongue, diarrhea, apathy As drug therapy, flushing and headache frequently accompany treatment doses Vitamin B₃ toxicity Hepatotoxicity is most serious problem Glucose intolerance, macular edema, macular cysts
B₅ (pantothenic acid) Functions in the metabolism and biosynthesis of many compounds Sources – broccoli, egg yolk, liver, yeast Inhibitors – none	Vitamin B₅ deficiency Deficiency has only been demonstrated experimentally; may have caused burning feet syndrome in prisoners Gastrointestinal disturbance, depression, paresthesias, ataxia, hypoglycemia Vitamin B₅ toxicity – none reported
B₆ (pyridoxal 5’-phosphate) Coenzyme in transaminase reactions Sources – legumes, meats, nuts, wheat bran Inhibitors – drugs such as cycloserine, isoniazid, L-dopa, penicillamine	Vitamin B₆ deficiency Seborrhea, glossitis, seizures, neuropathy, depression, confusion, microcytic anemia Vitamin B₆ toxicity – severe sensory neuropathy
B₇ (biotin) Coenzyme in transfer of carbonyl groups Sources – beans, egg yolks, liver, soy, yeast Inhibitors – egg whites	Biotin deficiency Only demonstrated in patients with short bowel syndrome receiving total parenteral nutrition Adults – mental status changes, anorexia, nausea, seborrheic rash Infants – hypotonia, lethargy, apathy, alopecia and rash on ears Biotin toxicity – None reported
Folate (B₉, folic acid, folacin) Coenzyme in metabolic reactions Sources – fortified breads, cereals and grain products, fruits, leafy vegetables, organ meats, yeast Inhibitors – anticonvulsants, chemotherapy agents, malabsorptive disorders (sprue), methotrexate	Folate deficiency Megaloblastic anemia – no neurologic symptoms Fetal open neural tube defects May be related to increased development of certain cancers Folate toxicity – none reported
B₁₂ (cobalamin) Cofactor for enzymatic reactions, metabolism of odd chain fatty acids, and methylation of homocysteine Sources – animal products, dairy products Inhibitors – achlorhydria, H2 receptor antagonists, overgrowth of intestinal organisms (eg, short bowel syndrome), proton-pump inhibitor drugs	Vitamin B₁₂ deficiency Deficiency found in ~30% of people >60 years. Megaloblastic (macrocytic) anemia Neurologic manifestations – loss of vibratory and position sense, abnormal gait, dementia, depression, loss of bowel and bladder control Vitamin B₁₂ toxicity – none reported
C (ascorbic acid) Coenzyme in formation of collagen and synthetic reactions Free radical scavenger with antioxidant activity Sources – citrus fruits, green vegetables, potatoes, tomatoes Inhibitors – smoking, hemodialysis	Vitamin C deficiency Scurvy – bleeding into skin, inflamed and bleeding gums, bleeding into joints, impaired bone growth Vitamin C toxicity – elevated liver enzymes, abdominal pain, diarrhea

Water Soluble Vitamins

Vitamin

Disease States

B₁ (thiamine)
Catalyzes reactions that produce energy

Sources – legumes, nuts, whole grains
Inhibitors – alcohol, coffee, loop diuretics, raw fish, shellfish, tea

Vitamin B₁ deficiency
Mainly found in alcoholics in U.S.
Wet beriberi – high-output cardiac failure
Dry beriberi – symmetrical peripheral neuropathy
Wernicke encephalopathy – beriberi combined with alcoholism; horizontal nystagmus, ophthalmoplegia, cerebellar ataxia, mental impairment

Wernicke-Korsakoff syndrome – coexistence of additional loss of memory and confabulatory psychosis

Vitamin B₁ toxicity – rare reports of anaphylaxis

B₂ (riboflavin)
Catalyzes reactions that produce energy; coenzyme in the flavoproteins that participate in tissue oxidation and respiration processes

Sources – broccoli, eggs, enriched breads, fish, lean meats, legumes, milk, other dairy products
Inhibitors – sunlight rapidly degrades the vitamin in foodstuffs

Vitamin B₂ deficiency
Mucocutaneous lesions including magenta tongue, angular stomatosis, seborrhea, cheilosis

Vitamin B₂ toxicity
None reported; gastrointestinal tract can only absorb limited quantities

B₃ (niacin)
Catalyzes the metabolism of fatty acids, amino acids and carbohydrates

Sources – beans, eggs, meat, milk
Inhibitors – B₂ or B₆ deficiency reduces conversion of tryptophan to niacin; drugs that may interfere with metabolism include alcohol, amitriptyline, chlorpromazine, imipramine

Vitamin B₃ deficiency
Mainly found in alcoholics in U.S.

Can occur in carcinoid and Hartnup diseases

Pellagra – pigmented rash in sun-exposed areas (Casal necklace), bright red tongue, diarrhea, apathy
As drug therapy, flushing and headache frequently accompany treatment doses

Vitamin B₃ toxicity
Hepatotoxicity is most serious problem
Glucose intolerance, macular edema, macular cysts

B₅ (pantothenic acid)
Functions in the metabolism and biosynthesis of many compounds

Sources – broccoli, egg yolk, liver, yeast
Inhibitors – none

Vitamin B₅ deficiency
Deficiency has only been demonstrated experimentally; may have caused burning feet syndrome in prisoners
Gastrointestinal disturbance, depression, paresthesias, ataxia, hypoglycemia

Vitamin B₅ toxicity – none reported

B₆ (pyridoxal 5’-phosphate)
Coenzyme in transaminase reactions

Sources – legumes, meats, nuts, wheat bran
Inhibitors – drugs such as cycloserine, isoniazid, L-dopa, penicillamine

Vitamin B₆ deficiency
Seborrhea, glossitis, seizures, neuropathy, depression, confusion, microcytic anemia

Vitamin B₆ toxicity – severe sensory neuropathy

B₇ (biotin)
Coenzyme in transfer of carbonyl groups

Sources – beans, egg yolks, liver, soy, yeast
Inhibitors – egg whites

Biotin deficiency
Only demonstrated in patients with short bowel syndrome receiving total parenteral nutrition
Adults – mental status changes, anorexia, nausea, seborrheic rash
Infants – hypotonia, lethargy, apathy, alopecia and rash on ears

Biotin toxicity – None reported

Folate (B₉, folic acid, folacin)
Coenzyme in metabolic reactions

Sources – fortified breads, cereals and grain products, fruits, leafy vegetables, organ meats, yeast
Inhibitors – anticonvulsants, chemotherapy agents, malabsorptive disorders (sprue), methotrexate

Folate deficiency
Megaloblastic anemia – no neurologic symptoms
Fetal open neural tube defects
May be related to increased development of certain cancers

Folate toxicity – none reported

B₁₂ (cobalamin)
Cofactor for enzymatic reactions, metabolism of odd chain fatty acids, and methylation of homocysteine

Sources – animal products, dairy products
Inhibitors – achlorhydria, H2 receptor antagonists, overgrowth of intestinal organisms (eg, short bowel syndrome), proton-pump inhibitor drugs

Vitamin B₁₂ deficiency
Deficiency found in ~30% of people >60 years.
Megaloblastic (macrocytic) anemia
Neurologic manifestations – loss of vibratory and position sense, abnormal gait, dementia, depression, loss of bowel and bladder control

Vitamin B₁₂ toxicity – none reported

C (ascorbic acid)
Coenzyme in formation of collagen and synthetic reactions
Free radical scavenger with antioxidant activity

Sources – citrus fruits, green vegetables, potatoes, tomatoes
Inhibitors – smoking, hemodialysis

Vitamin C deficiency
Scurvy – bleeding into skin, inflamed and bleeding gums, bleeding into joints, impaired bone growth

Vitamin C toxicity – elevated liver enzymes, abdominal pain, diarrhea

Fat soluble vitamins

Fat Soluble Vitamins
Vitamin	Disease States
A (retinol) Required for normal vision, growth and differentiation of epithelial tissue as well as bone growth, immunity, reproduction and embryonic development Sources – beef, egg yolk, fish, liver, vegetables Inhibitors – ethanol, mineral oil, neomycin, cholestyramine	Vitamin A deficiency Ophthalmic – xerophthalmia, Bitot spots, corneal ulcers Dermatologic – hyperkeratotic skin lesions Vitamin A toxicity Acute – increased intracranial pressure, vertigo, diplopia, seizures, headaches Chronic – cheilosis, glossitis, alopecia, bone pain, hyperlipidemia, liver fibrosis
D (calcitriol) Hormone precursor Required for calcium absorption, bone metabolism, regulation of cell development and the immune system Sources – dairy, egg yolks, fish oils, fortified foods; also synthesized in response to ultraviolet radiation Inhibitors – barbiturates, isoniazid, phenobarbital, phenytoin, rifampin, sunblock	Vitamin D deficiency Children – rickets and rachitic rosaries (expansion of growth plate) Adults – 33% of older adults are deficient (estimated) Osteomalacia, osteoporosis; hypocalcemia and hypophosphatemia with impaired mineralization of bone matrix; associated with cardiovascular disease, cancer (colon, breast), autoimmune disease Vitamin D toxicity Rare; associated with ≥10,000 IU/day intake (not seen until 25(OH)D ≥150 ng/mL)
E (tocopherol) Coenzyme in formation of collagen, synthetic reactions, antioxidant activity and free radical scavenger Sources – sunflower oil, safflower oil, wheat germ, soybean Inhibitors – none	Vitamin E deficiency Almost exclusively in severe and prolonged malabsorptive disorders Peripheral neuropathy – areflexia, ataxia, ophthalmoplegia, skeletal myopathy Vitamin E toxicity Reduced platelet aggregation, interference with warfarin treatment
K (phylloquinone [K₁], menaquinone [K₂]) Essential for carboxylation of glutamic acid residues in proteins required for coagulation Sources – butter, coffee, egg yolk, green leafy vegetables, ground beef, milk, pears Inhibitors – broad spectrum antibiotics, warfarin	Vitamin K deficiency Hemorrhage of mucous membranes and gastrointestinal tract Vitamin K toxicity Infants – hemolytic anemia and hyperbilirubinemia

Fat Soluble Vitamins

Vitamin

Disease States

A (retinol)
Required for normal vision, growth and differentiation of epithelial tissue as well as bone growth, immunity, reproduction and embryonic development

Sources – beef, egg yolk, fish, liver, vegetables
Inhibitors – ethanol, mineral oil, neomycin, cholestyramine

Vitamin A deficiency
Ophthalmic – xerophthalmia, Bitot spots, corneal ulcers
Dermatologic – hyperkeratotic skin lesions

Vitamin A toxicity
Acute – increased intracranial pressure, vertigo, diplopia, seizures, headaches
Chronic – cheilosis, glossitis, alopecia, bone pain, hyperlipidemia, liver fibrosis

D (calcitriol)
Hormone precursor
Required for calcium absorption, bone metabolism, regulation of cell development and the immune system

Sources – dairy, egg yolks, fish oils, fortified foods; also synthesized in response to ultraviolet radiation
Inhibitors – barbiturates, isoniazid, phenobarbital, phenytoin, rifampin, sunblock

Vitamin D deficiency
Children – rickets and rachitic rosaries (expansion of growth plate)
Adults – 33% of older adults are deficient (estimated)
Osteomalacia, osteoporosis; hypocalcemia and hypophosphatemia with impaired mineralization of bone matrix; associated with cardiovascular disease, cancer (colon, breast), autoimmune disease

Vitamin D toxicity
Rare; associated with ≥10,000 IU/day intake (not seen until 25(OH)D ≥150 ng/mL)

E (tocopherol)
Coenzyme in formation of collagen, synthetic reactions, antioxidant activity and free radical scavenger

Sources – sunflower oil, safflower oil, wheat germ, soybean
Inhibitors – none

Vitamin E deficiency
Almost exclusively in severe and prolonged malabsorptive disorders
Peripheral neuropathy – areflexia, ataxia, ophthalmoplegia, skeletal myopathy

Vitamin E toxicity
Reduced platelet aggregation, interference with warfarin treatment

K (phylloquinone [K₁], menaquinone [K₂])
Essential for carboxylation of glutamic acid residues in proteins required for coagulation

Sources – butter, coffee, egg yolk, green leafy vegetables, ground beef, milk, pears
Inhibitors – broad spectrum antibiotics, warfarin

Vitamin K deficiency
Hemorrhage of mucous membranes and gastrointestinal tract

Vitamin K toxicity
Infants – hemolytic anemia and hyperbilirubinemia

Tests generally appear in the order most useful for common clinical situations

Test name: Vitamin B₁ (Thiamine), Whole Blood

ARUP #: 0080388

Methodology: Quantitative High Performance Liquid Chromatography

Use:

Preferred specimen for thiamine assessment in patients with suspected deficiency

Test name: Vitamin B₂ (Riboflavin)

ARUP #: 0081123

Methodology: Quantitative High Performance Liquid Chromatography

Use:

Assess riboflavin concentration in serum or plasma

Test name: Niacin (Vitamin B₃)

ARUP #: 0092168

Methodology: Quantitative High Performance Liquid Chromatography

Use:

Assess niacin concentration in plasma

Test name: Vitamin B₅ (Pantothenic Acid)

ARUP #: 2003186

Methodology: High Performance Liquid Chromatography

Use:

Assess pantothenic acid concentration

Test name: Vitamin B₆ (Pyridoxal 5-Phosphate)

ARUP #: 0080111

Methodology: Quantitative High Performance Liquid Chromatography

Use:

Assess concentration in plasma

Specimen collected following an 8-hour or overnight fast accurately indicates vitamin B₆ nutritional status; non-fasting specimen concentration reflects recent vitamin intake

Test name: Vitamin B₇ (Biotin)

ARUP #: 2003184

Methodology: Bioassay

Use:

Assess biotin concentration

Test name: Vitamin B₁₂ & Folate

ARUP #: 0070160

Methodology: Quantitative Chemiluminescent Immunoassay

Use:

Assess vitamin B₁₂ and folate concentration

Test name: Vitamin C, Plasma

ARUP #: 0080380

Methodology: Quantitative Spectrophotometry

Use:

Assess vitamin C concentration

Test name: Vitamin A (Retinol), Serum or Plasma

ARUP #: 0080525

Methodology: Quantitative High Performance Liquid Chromatography

Use:

Assess vitamin A concentration

Includes measurement of retinol and retinyl palmitate concentration

Limitations:

This assay does not measure other vitamin A metabolites such as retinaldehyde or retinoic acid

Test name: Vitamin D, 25-Hydroxy

ARUP #: 0080379

Methodology: Quantitative Chemiluminescent Immunoassay

Use:

Appropriate for assessment of vitamin D status, including general population screening for deficiency; can also be used for assessment of hypocalcemia

Chemiluminescence is preferred over the radioimmunoassay

Test name: Vitamin E, Serum or Plasma

ARUP #: 0080521

Methodology: Quantitative High Performance Liquid Chromatography

Use:

Assess vitamin E concentration

Includes measurement of alpha tocopherol and gamma tocopherol concentrations

Test name: Vitamin K₁, Serum

ARUP #: 0099225

Methodology: Quantitative High Performance Liquid Chromatography

Use:

Assess vitamin K₁ concentration

Additional Tests Available

Test name: Vitamin B₁ (Thiamine), Plasma

ARUP #: 0080389

Methodology: Quantitative High Performance Liquid Chromatography

Comments:

Assess thiamine concentration in plasma to monitor vitamin B₁ concentration in patients receiving supplementation

Test name: 25-Hydroxyvitamin D₂ and D₃ by Tandem Mass Spectrometry, Serum

ARUP #: 2002348

Methodology: Quantitative High Performance Liquid Chromatography-Tandem Mass Spectrometry

Comments:

Assess vitamin D concentration

ARUP is unable to provide reliable results for specimens from infants (less than one year of age), since highly specialized test methodology is required; ARUP will refer all infant specimens to a lab that is able to perform this methodology

Test name: Vitamin B₁₂

ARUP #: 0070150

Methodology: Quantitative Chemiluminescent Immunoassay

Comments:

Assess vitamin B₁₂ concentration

Test name: Folate, Serum

ARUP #: 0070070

Methodology: Quantitative Chemiluminescent Immunoassay

Comments:

Assess folate concentration in serum

Test name: Vitamin B₁₂ with Reflex to Methylmalonic Acid, Serum (Vitamin B₁₂ Deficiency)

ARUP #: 0055662