Vitamins Flashcards
Fat soluble vitamins
Vitamins A,D,E, and K
Two water soluble vitamins that are stored in the liver
B12 and folate
4 major functions of vitamin A
Antioxidant
Constituent of visual pigments (retinal)
Essential for normal differentiation of epithelial cells
Prevents squamous metaplasia
Two conditions that can be treated with vitamin A
Measles and AML, subtype M3
Symptoms of vitamin A deficiency
Night blindness, dry skin, keratomalacia, squamous metaplasia
Symptoms of vitamin A excess
Arthralgias, fatigue, headaches, skin changes, sore throat, alopecia,
Teratogenic (cleft palate, cardiac abnormalities): pregnancy test and two forms of contraception are needed before isotretinoin is used for severe acne
4 enzymes that use vitamin B1 as a cofactor
Pyruvate dehydrogenase (links glycolysis to TCA)
Alpha-ketoglutarate dehydrogenase (TCA)
Transketolase (HMP shunt)
BCAA dehydrogenase
3 conditions seen in vitamin B1 deficiency
Wernicke-Korsakoff: confusion, ophthalmoplegia, ataxia (classic triad) + confabulation, personality change, memory loss (permanent)
Dry beriberi: polyneuritis, symmetrical muscle wasting
Wet beriberi: high output cardiac failure (dilated cardiomyopathy), edema
Condition seen with chronic thiamine deficiency that affects cerebellum
Alcoholic cerebellar degeneration: loss of Purkinje cells in anterior lobes and vermis
Causes progressive, wide-based gait ataxia, truncal instability, intention tremor
Function of vitamin B2 (riboflavin)
Cofactor in oxidation and reduction (e.g. FADH2)
Symptoms of B2 deficiency
Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), corneal vascularization, magenta colored tongue
Function of vitamin B3 (niacin)
Constituent of NAD+ ,NADP+ (used in redox reactions)
Amino acid necessary for synthesis of niacin
Tryptophan, also requires vitamin B6
Symptoms of niacin deficiency
Glossitis and severe deficiency leads to pellagra (diarrhea, dermatitis, dementia)
Conditions where niacin deficiency may be seen
Hartnup’s (decreased tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism), and isoniazid therapy (decreased B6)
Symptoms of niacin excess
Facial flushing (can prevent with aspirin pre-treatment)
Function of vitamin B5 (pantothenate)
Essential component of CoA (a cofactor for acyl transfers) and fatty acid synthase
Symptoms of vitamin B5 defieciency
Dermatitis, enteritis, alopecia, adrenal insufficiency
Function of vitamin B6 (pyridoxine)
Cofactor used in transamination reactions, decarboxylation reactions, and glycogen phosphorylase
Symptoms of vitamin B6 deficiency
Convulsions, hyperirritability, peripheral neuropathy (seen in isoniazid use), sideroblastic anemias due to impaired hemoglobin synthesis and iron excess
Function of vitamin B7 (biotin)
Cofactor for carboxylation enzymes including:
1) pyruvate carboxylase
2) acetyl-CoA carboxylase
3) propionyl-CoA carboxylase
Function of vitamin B9 (folic acid)
Converted to THF, a coenzyme for 1 carbon transfers/methylation reactions
Also important for synthesis of nitrogenous bases in DNA and RNA
Symptoms of folic acid deficiency
Macrocytic, megaloblastic anemia (no neurologic symptoms), homocysteinemia (increased risk for DVT and atherosclerosis)
Function of vitamin B12
Cofactor for homocysteine methyltransferase (transfers methyl groups) and methylmalonyl-CoA mutase
Symptoms of B12 deficiency
Macrocytic, megaloblastic anemia with hypersegmented neutrophils (paressthesias, subacute combined degeneration)
Cause of B12 deficiency seen with normal urinary excretion of radiolabeled B12
Poor B12 intake
Cause of B12 deficiency seen with diminished urinary excretion of radiolabeled B12
Impaired intestinal absorption
Cause of B12 deficiency seen with with normal urinary excretion after addition of intrinsic factor
Pernicious anemia
Cause of B12 deficiency seen with diminished urinary excretion after addition of intrinsic factor
Malabsorption syndrome such as pancreatic insufficiency, bacterial overgrowth, or short gut syndrome
4 functions of vitamin C
Antioxidant
Facilitates iron absorption
Hydroyxlation of proline and lysine in collagen synthesis
Necessary for dopamine hydroxylase which converts DA to NE
Symptoms of vitamin C deficiency
Scurvy: swollen gums, bruising, hemarthrosis, anemia, poor wound healing, weakened immune response
Collagen synthesis defect
Symptoms of vitamin C excess
N/V, diarrhea, fatigue, sleep problems
Can increase risk of iron toxicity in predisposed people (those with transfusions, hereditary hemochromatosis)
Function of vitamin D
Increases intestinal absorption of calcium and phosphate, and increases bone mineralization
Symptoms of vitamin D deficiency
Rickets (children, bone pain and deformities) and osteomalacia (adults, bone pain and weakness), hypocalcemic tetany
Breast milk has low vitamin-D (must supplement in dark-skin peopled)
Symptoms of vitamin D excess
Hypercalcemia, hypercalciuria, loss of appetite, stupor
Disease that can cause vitamin D excess
Sarcoidosis: increases activation of vitamin D by epithelioid macrophages
Function of vitamin E
Antioxidant (protects RBCs and membranes from free-radical damage)
Symptoms of vitamin E deficiency
Increased fragility of RBCs (hemolytic anemia), muscle weakness, posterior column and spinocerebellar tract demyelination, infertility
Symptoms of vitamin E excess
Potential hemorrhage in warfarin patients
Function of vitamin K
Catalyzes gamma-carboxylation of glutamic acid residues on various proteins associated with blood clotting
Symptoms of vitamin K deficiency
Neonatal hemorrhage with prolonged PT and aPTT but normal bleeding time
