Term
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Definition
- Retinol
- Fat-soluble
- Function: antioxidant; constituent of visual pigmants (retinal; "a" is for "active"); essential for normal differentiation of epithelial cells into specialized tissue (pancreatic cells, mucus-secreting cells).
- Deficiency: Night blindness, dry skin (no mucus!)
- Excess: Arthralgias, fatigue, headaches, skin changes, sore throat, alopecia.
- TERATOGENIC: cleft palate, cardiac abnormalities); pregnancy test must be done before isotretinoin is prescribed for severe acne.
- Found in liver and leafy vegetables.
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Term
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Definition
- Thaimine
- Function: In thiamine pyrophosphate (TPP), a cofactor for several enzymes:
- Pyruvate dehydrogenase (glycolysis)
- alpha-ketoglutarate dehydrogenase (TCA cycle)
- Transketolase (HMP shunt)
- Branched-chain AA dehydrogenase
Deficiency: Impaired glucose breakdown -> ATP depletion; highly aerobic tissues (brain and heart) are affected first.
- Wernicke-Korsakoff (drunks): confusion, ophtalmoplegia, confabulation, personality change
- Beriberi (malnutrition/malabsorption): dry - polyneuritis, symmetrical muscle wasting. wet - high-output cardiac failure (dilated cardiomyopathy), edema.
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Term
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Definition
- Riboflavin
- Function: Cofactor in oxidation and reduction (eg, FADH2, FMN).
- Deficiency: Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), Corneal vascularization.
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Term
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Definition
- Niacin
- Function: Constituent of NAD and NADP (used in redox rxns). Derived from tryptophan. Synthesis requires vitamin b6.
- Deficiency: Glossitis. Severe deficiency leads to pellagra, which can be caused by Hartnup disease (decreased tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism), and INH (decreased vitamin B6).
- Excess: Facial flushing (due to pharmacologic doses for treatment of hyperlipidemia.)
- Note: Vitamin B3 in corn not absorbable unless treated. Excess untreated corn in diet can lead to pellagra.
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Term
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Definition
- Pantothenate
- Function: Essential component of CoA (a cofactor for acyl transfers) and fatty acid synthase.
- Deficiency: Dermatitis, enteritis, alopecia, adrenal insufficiency.
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Term
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Definition
- Pyridoxine
- Function: Converted to pyridoxal phosphate, a cofactor used in transamination (eg, ALT and AST), decarboxylation rxns, glycogen phosphorylase, cystathionine synthesis, and heme synthesis. Req'd for the synthesis of niacin from tryptophan.
- Deficiency: Convulsions, hyperirritability, peripheral neuropathy, (deficiency inducible by INH and oral contraceptives), sideroblastic anemias.
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Term
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Definition
- Cobalamin
- Function: Cofactor for homocysteine methyltransferase (transfers CH3 groups as methylcobalamin) and methylmalonyl-CoA mutase.
- Deficiency: Macrocytic, megaloblasic anemia, hypersegmented PMN's, neurologic symptoms (paresthesias, subacute combined degeneration) due to abnormal myelin. Prolonged deficiency leads to irreversible nervous system damage.
- Found in animal products, synthesized by microorganisms. Very large reserve pool (several years stored in the liver).
- Deficiency: Cuased by malabsorption, lack of IF, or absence of terminal ilieum (Chron's).
- Schilling test for dx.
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Term
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Definition
- Function: Converted to THF, a coenzyme for 1-carbon transfer/methylation rxns. Important for the synthesis of nitrogenous bases in DNA and RNA
- Deficiency: Macrocytic, megaloblastic anemia; no neurologic symptoms (as opposed to vit B12 deficiency). Most common vitamin deficiency in the US. Seen in alcoholism, drugs (phenytoin and anti-cancer) and pregnancy
- Small reserve pool in liver; from green leaves
- Supplemental in pregnancy.
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Term
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Definition
- ATP + methionine -> SAM
- SAM transfers methyl units
- Regeneration of methinine (and thus SAM) is dependent on vitamin B12 and folate.
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Term
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Definition
- Function: Cofactor for carboxylation enzymes, which add a 1-carbon group):
- pyruvate carboxylase: pyruvate (3C) -> oxaloacetate (4C)
- Acetyl-CoA carboxylase: Acetyl-CoA (3C) -> malonyl-CoA (4C)
- Propionyl-CoA carboxylase: Proprionyl-CoA (3C) -> methylmalonyl-CoA (4C)
- Deficiency: relatively rare. Dermatitis, alopecia, enteritis. Caused by antibiotic use or excessive ingestion of raw eggs.
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Term
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Definition
- Ascorbic Acid
- Function
- Antioxidant.
- Facilitates Fe absorption by keeping iron in Fe2+ state (more absorbable)
- Necessary for hydroxylation of proline and lysine in collage synthesis
- Necessary for dopamine Beta-hydroxylase, which converts dopamine to NE
- Deficiency: Scurvy -> swollen gums, bruising, anemia, poor wound healing
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Term
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Definition
- Types:
- D2 = ergocalciferol - ingested from plants, used in pharm
- D3 = cholecalciferol - consumed in milk, formed in sun-exposed skin
- 25-OH D3 = storage form
- 1, 25-(OH)2 D3 (calcitriol) = active form
- Function: increased intestinal absorption of calcium and phosphate, increased bone resorption
- Deficiency: Rickets in children (bending bones), osteomalacia in adults (soft bones), hypocalcemic tetany.
- Excess: Hypercalcemia, hypercalciuria, loss of appetite, stupor. Seen in sarcoidosis (increased activation of vitamin D by epitheliod macrophages).
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Term
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Definition
- Function: Antioxidant (protects erythrocytes and membranes from free-radical damage).
- Deficiency: increased fragility of erythrocytes (hemolytic anemia), muscle weakness, neurodysfunction.
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Term
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Definition
- Function: Catalyzes gamma-carboxylation of glutamic acid residues on various proteins concerned with blood clotting. Synthesized by intestinal flora.
- Deficiency: Neonatal hemorrhage with increased PT and an increased aPTT but normal bleeding time (neonates have sterile intestines and are unable to synthesize vitamin K). Can also occure after prolonged use of broad-spec antibiotics
- Necessary for synthesis of clotting factors II, VII, IX, X, and protein C and S.
- Warfarin: vitamin K antagonist.
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