Vitamins Flashcards
B1 (Thiamine, TPP)
Purpose: Used as a cofactor for the following enzymes
- Pyruvate dehydrogenase
- A-ketoglutarate dehydrogenase
- Transkelotase
- Branch chain ketoacid dehydrogenase
Deficiency: (alcoholics, and malnutrition)
- Impaired glucose breakdown–> ATP deficiency (made worse with glucose infusion)
- Highly aerobic tissues are affected first (brain, heart)
- Wernike korsakoff: ataxia, opthalmoplegia, confabulation
- Wet Beriberi: High output HF (Dilated cardiomyopathy), edema
- Dry BeriBeri: polyneuritis, and symmetrical muscle weakness
dx: inc. transketolase activity with B1 admin
B2 (Riboflavin)
Function: (FAD and FMN) Component of redox reactions- most dehydrogenase enzymes
Deficiency:
Interstitial keratitis (corneal vascularization)
Cheilosis
Glossitis
Dermatis: greasy, scaly skin
Bone marrow hypoplasia
B3 (Niacin)
Purpose: (NAD+, NADP+), used in redox reactions (dehydrogenases), tx dyslipidemia (dec. VLDL and raise HDL)
*Derived from tryptophan and requires B2 and B6 for synthesis.
Deficiency: Pellegra
- Diarrhea, Dementia, Death, Dermatitis (collar dermatitis C3/C4), hyperpigmenation of sun exposed areas
Excess: Flushing (due to PG release NOT histamine release), hyperglycemia, hyperurecemia
B5 (pantothenic Acid)
Function: essential for coenzyme A (cofactor for acyl transfers) and FA synthase
Deficiency: Dermatitis, alopecia, enteritis, and adrenal insufficiency
B6 (Pyridoxine)
Function: converted to pyridoxical phosphate (PLP), cofactor for the following
- Transaminases (ALT, AST)
- Decarboxylation reaction
- glycogen phosphorylase
- Synthesis of Cystathione, heme, niacin, histamine
- synthesis of NT: epi, norepi, seratonin, dopamine, and GABA
Deficieny:
- Convulsions (no GABA)
- Hyper Irritability, peripheral neuropathy (induced by INH, and oral contraceptives)
- Sideroblastic anemia (can’t synthesize heme and iron excess)
B7 (Biotin)
Function: cofactor for carboxylation reactions (add Carbon group)
- Pyruvate carboxylase (pyruvate –> oxaloactate: gluconeo)
- Acetyl CoA carboxylase (acetyl coA–> malonyl CoA: FA synthesis)
- Propionyl CoA carboxylase (Propionyl CoA–> Methylmalonyl CoA: FA use in TCA cycle)
Deficieny: Rare- association with excessive egg white ingestion (avid in egg whites binds to B7)
- alopecia, enteritis, dermatitis
B9 (Folate)
Function: Converted to THF, used in DNA synthesis of nitrogenous bases in DNA and RNA
- found mostly in leafy greens, small reserve pool in the Liver
Deficieny: macrocytic, megaloblastic anemia with hypersegmented PMNs, glossitis, NO NEUROLOGICAL SX
- homocystinuria, with normal methylmalonic acid levels
** mostly seen in alcoholism and pregnancy
** very common
B12 (Cobalamin)
Function: Cofactor for Homocysteine Methyltransferase and methylmalonyl CoA mutase (Heme synthesis)
* found in animal products, stored in the liver, need IF for absorption
Deficiency: (VEGANS, malabsorption, absence of terminal ileum, lack of IF (pernicous anemia) )
- macrocytic, megaloblastic anemia (no heme synthesis) with hypersegmented PMNs
- Paresthesias and subacute combined degeneration- dorsal columns, CST, spinocerebellar tract- (due to defect in myelin synthesis - via the heme synthesis pathway)
- inc. homocysteine levels and methylmalonic acid levelss
- prolonged deficieny: irreversible neuropathy
Vitamin C (ascorbic acid)
Function: antioxidant, facilitates iron absorption by reducing it to Fe2+ state, hydroxylation of lysine and proline in collagen syn., dopamine hydroxylase (Dopamine –> NE)
* Found in fruits and vegetables
Deficiency:
- Scurvy: failure to hydroxylate lysine and proline- failed collagen synthesis
– swollen gums, curly hair, petechia, poor wound healing, hemarthrosis, sub periosteal hemorrhages
Excess: N/V/fatigue, calcium oxalate Nephroliathiasis, inc risk of iron toxicity in predisposed individuals
Vitamin D
Active form: calcitriol (1, 25)
Storage form: 25, OH D3, D3 from the sunlight
D2: ergocalciferol - from plants
Function: intestinal absorption of Ca and phosphate, inc bone mineralization
Deficiency: Rickets in children, osteomalacia in adults, hypocalcemic tetany, exacerbated by low sun exposure, pigmented skin, and prematurity
*breast fed infants need vitaminD
Excess: Hypercalcemia, hypercalciuria, loss of appetite, stupor, SEEN IN GRANULOMATOUS DISEASE (inc. activation of vitD by epitheloid macrophages)
Vitamin E (tocopherol, tocotrienol)
Function: Antioxidant (protects RBC membranes and membranes from free radical damage), can enhance anticoagulant effects of warfarin
Deficiency: Hemolytic anemia, ancatholysis, muscle weakness, posterior column and spinocerebellar tract demyelinateion
** neurologic presentation similar to vitB12 but without the megaloblastic anemia and hypersegmented NT or the inc. in methymalonic acid levels
Vitamin K (phytomenadione, phylloquinone, phytonadione)
Function: Cofactor for gamma-carboxylation of glutamic acid residues on various proteins required for blood clotting, synthesized by the intestinal flora
Deficiency: neonatal hemorrhage with inc. PT and aPPT (neonates are unable to synthesize because they have no flora- not in breast milk)
- may occur after prolonged anti-biotic use
Zinc
Function : Used in 100+ enzymes, formation of zinc finger motif (transcription factor motif)
Deficiency: delayed wound healing, hypogonadism, dec adult hair, anosmia, dysguesia, acrodermatitis enteropathica. May predispose to alcoholic Cirrhosis
Vitamin A
Function: Anti-oxidant, prevents squamous metaplasia, promotes differentiation of epithelial cells in specialized cells (pancreatic and mucus secreting), used to tx measles and AML M3
Deficiency: Loss of night vision, dry scaley skin (xerosis cutis), keratomalacia (degradation of the cornea), bitot spots on the cornea, immunosuppression
Excess: N/V/ vertigo and blurred vision, hepatotoxicity and enlargement, pseudotumor cerebri, dry scaly skin, alopecia, teratogenic
