Vitamins Flashcards
B1 (Thiamine)
Cofactor for dehydrogenase enzymes–
1) Pyruvate dehyrdrogenase: glycolysis to TCA cycle
2) a-ketoglutarate dehydrogenase
3) Transketolase (HMP shunt)
4) Branched-chain ketoacid dehydrogenase
B1 (Thiamine) Deficiency
Found with malnutrition and alcoholism
Dx: Increase RBC transketolase activity following B1 admin
ATP depletion worsened by glucose
Aerobic tissues affected 1st (brain, heart)
Wernicke-Korsakoff syndrome
Classic triad: confusion, opthalmoplegia, ataxia
Confabulation, personality change, memory loss (perm)
Damage to the medial dorsal nucleus of the thalamus, mammillary bodies.
Beri Beri
Dry: Polyneuritis, symmetrical muscle wasting
Wet: High output cardiac failure (dilated CM), edema
B2 (Riboflavin) Function & Deficiency
Component of FAD and FMN; Cofactor for redox reactions
Deficiency:
Cheilosis (inflammation of lips) “magenta tongue”
Corneal vascularization
B3 (Niacin)
Component of NAD+, NADP-
Derived from Tryptophan
Synthesis requires B2 & B6
Used to lower VLDL, raise HDL
B3 (Niacin) Deficiency & Excess
Deficiency: Typically corn diet or Hartnup disease (Dec T absorption), Carcinoid (Inc T metabolism), INH (Dec B6)
- Glossitis
- Pellagra: Diarrhea, Dermatitis (sun-exposed), Dementia
Excess: Facial flushing (PG induced), hyperglycemia, hyperuricemia
B5 (Pantothenate) Function & Deficiency
Essential component of Coenzyme A & Fatty acid synthase
Defeciency: Dermatitis, Enteritis, Alopecia, Adrenal Insufficiency
B6 (Pyridoxine)
Cofactor used in transamination, decarboxylation rxns, glycogen phosphorylase.
Synthesis of: Cystathionine, Heme, Niacin, Histamine, NT (5HT, E, NE, DA & GABA)
B6 Deficiency
Inducible by INH and OCPs.
Results in: Convulsions, Hyperirritability, Peripheral Neuropathy, Sideroblastic anemias (2/2 impaired heme)
B7 Function & Deficiency
Cofactor for carboxylation enxymes
- Pyruvate carboxylase
- Acetyl-CoA carboxylase
- Propionyl-CoA carboxylase
Def is rare from Abx or Excessive ingestion of raw egg whites. Results in Dermatitis, Alopecia, Enteritis
B9 (Folic Acid)
Converted to Tetrahydrofolate (THF) Coenzyme for methylation reactions
Important for synthesis of nitrogenous bases
Found in green vegies and absorbed in the jejunum.
B9 (Folic Acid) Deficiency
Most common vitamin deficiency in US
Drugs- Phenytoin, Sulfonamide, Methotrexate
Alcoholism & Pregnancy
- Macrocytic, megaloblastic anemia with PMNs
- Increased Homocysteine; Normal methylmalonic acid
- NO NEURO SX
B12 (Cobalamin)
Cofactor for homocysteine methyltransferase AND methylmalonyl-CoA mutase
Found in animal products, synthesized by microorganisms
B12 (Cobalamin) Deficiency
Insufficient intake (vegans) Malabsorption (sprue, D. latum) Pernicious Anemia (no IF) Gastric Bypass Chron's (No terminal ileum)
- Macrocytic, megaloblastic anemia with PMNs
- Increased homocysteine AND methylmalonic acid
- Subacute combined (dorsal columns, lateral corticospinal & spinocerebellar) degeneration 2/2 abnormal myelin
A (Retinol)
Antioxidant
Visual pigments & Epithelial cell differentiation
Prevents squamous metaplasia
Treats: measles, AML-M3 & acne (topical)
Vitamin A Deficiency & Excess
Deficiency:
- Night blindness (nyctalopia)
- Dry, scaly skin (xerosis cutis)
- Corneal Degeneration (keratomalacia)
- Dry eye (xeropthalmia)
Excess:
- Arthralgias
- Psedotumor cerebri
- Osteoporosis
- Teratogenic!
Vitamin C (Ascorbic Acid)
Antioxidant found in fruits and vegetables
Facilitates iron absorption
Necessary for collagen synthese (hydroxylation of proline and lysine)
Necessary for conversion of DA to NE (dopamine B-hydroxylase)
Vitamin C (Ascorbic Acid) Deficiency & Excess
Deficiency (Scurvy): swollen gums, bruising, hemarthosis, anemia, poor wound healing, perifollicular/subperiosteal hemorrhage, “corkscrew” hair
Excess: N/V/D, fatigue, Ca Oxalate stones
Vitamin D
D2: Ergocalciferol (plants)
D3: Cholecalciferol (milk or UV light on skin)
23-OH D3: Storage form (made in liver)
1, 25-OH D3 (calcitriol): Active form (made in kidney)
Increases intestinal absorption of Ca & phosphate
Increases bone mineralization
Vitamin D Deficiency & Excess
Deficiency- Rickets (children) Osteomalacia (adults) Can cause hypocalcemic tetany Breastfeed infants should be supplemental with oral vit D
Excess: Hypercalcemia, hypercalciuria, loss of appetite, stupor. Seen in sarcoid (2/2 inc activation of D by macrophages)
Vitamin E (Tocopherol) Function & Deficiency
Antioxidant, protects from free radical damage
Can enhance the anticoagulant effects of Warfarin
Deficiency: Hemolytic anemia (2/2 membrane fragility); muscle weakness, posterior column & spinocerebellar tract demylelination. Retinitis Pigementosa.
Vitamin K Function & Deficiency
Cofactor for g-carboxylation of glutamic acid residues on blood clotting factors (II, VII, IX, X, protein C & S).
Produced by intestinal flora
Deficiency: Neonatal hemorrhage (Inc PT/PTT, normal BT)
