Vitamin deficiencies and toxicities Flashcards
B1 - reactions
Thiamine - Pyruvate Dehydrogenase, alphaketoglutarate dehydrogenase, HMP shunt (transketolase), Branched-chain AA dehydrogenase
B1 deficiency
ATP depletion - Dry and wet BeriBeri - heart and brain affected first; Wernicke= ophthalmoplegia, mental status, ataxia; Korsakoff- memory, confabulation, personality change
B2 reaction and deficiency
FADH2, Riboflavin; Cheilosis and corneal vascularization
B3 reaction
NAD, NADP; derived from tryptophan; synthesis requires B6
B3 deficiency
pallagra (dementia, diarrhea, dermititis), aggression, confusion, ataxia; caused by Hartnup disease, INH use, Carcinoid
B3 excess
Facial flushing that can be lessened by taking aspirin
B5
Pentothenate; essential component of CoA (acyl transfers, TCA cycle, FA synthesis); deficiency dermatitis, enteritis, alopecia, ADRENAL INSUFFICIENCY (important in cholesterol synthesis)
B6 reactions
Pyridoxine - glutamate to GABA, Glycine to Heme, Tryptophan to naicin, Homocystein to cysteine and SAM, Histidine to Histamine, Dopa to Dopamine,
B6 shortage
convulsions (absence of gaba), sideroblastic anemia from inhibition of ALA synthase, peripheral neuropathy; deficiency inducible by INH or oral contraceptives
B12 reactions
Homocystein to methionine and mehylalonyl-CoA to Succinyl CoA
B12 deficiency
Macrocytic, megaloblastic anemia; peripheral neuropaty; dorsal column and lateral corticospinal tract dysfunction (all due to abnormal myelin); causes: celiac, Crohn, diphyllobothrium latum, pernicious anemia; test with Schilling test
Folic Acid function
Active form is tetrahydrofolate. Is a carbon donor. Synthesis in nitrogenous bases for DNA and RNA. Activated form is made in homocystein to methionine reaction with B12.
Folic Acid Deficiency
Macrocytic, megaloblastic anemia; no neurologic symptoms. Most common in US. Alcoholism and pregnancy. Caused by drugs (phenytoin, sulfonamides, MTX); excess can exacerbate any B12 deficiency
SAM
made from ATP and methionine. Methyl donor. Used for Epinepherine to epinepherine conversion; Used for methylation of 5’ guanosine cap during mRNA processing
Biotin function
Carboxylation; propionyl-CoA to Methylmalonyl CoA (odd-chain Fas); Pyruvate carboxylase (start of gluconeogenesis); Acetyl-CoA carboxylase (Acetyl-CoA to Malonyl CoA to start off FA synthesis)
Biotin deficiency
Alopecia, gastroenteritis, Dermatitis; Caused by antibiotic use or excessive ingestion of RAW EGGS
Vitamin C Function
Hydroxylation of Lysine and proline; absorption of Fe and maintenance of ferrous state; cofactor for dopamine to NE.
Vit C defenciency
Scurvy- swollen gums, bruising, hemarthrosis, anemia, poor wound healing, weakened immune response, (anemia is due to poor Fe intake and extensive oxidative damage to RBCs as Vit C is an antioxidant)
Excess of Vit C
Fe overload especially those at risk like people with hemochromatosis; Nausea, vomiting, idarrhea, fatigue, sleep problems
Vitamin A function
Antioxidant; visual pigments (retinal); normal differentiation of specialized epithelium (prevents squamous metaplasia); used to treat measles and M3 AML; topical for wrinkles and acne
Vit. A deficiency
Night blindness, dry skin, squamous metaplasia of conjunctiva (Bitot’s spots), xerophthalmia
Vit. A excess
Arthralgias, fatigue, headache, SKIN CHANGES, sore throat, alopecia, teratogenic, increases in CSF pressure (can sometimes see cerebral edema through opthalmoscope)
Vit. D excess
hypercalcemia, hypercalciuria. Abdominal pains. Seen in sarcoidosis because epithelioid cells
Vit D.
Ergocalciferol (D2 - plants); Cholecalciferol (D3 - skin); 1,25-calcitrol (active)
Vit E
alpha-tocopherol; antioxidant protects erythrocytes and membranes from free-radical damage
Vit E deficiency
Fragility of erythrocytes, muscle weakness; Posterior column and spinocerebellar tract demyelination.
Vit. K
gamma carboxylation of glutamic acid residues on factors 2, 7, 9, 10 C and S. Deficiency leads to hemorrhage (neonates are susceptible from lack of intestinal flora)
Zinc deficiency
Functions in 100+ enzymes, zinc-finger transcription factor, carbonic anhydrase; deficiency leads to defect in synthesis of proteins etc.; delayed wound healing, hypogonadism, decreased adult hari, changes in taste dygeusia, changes in smell anosmia, impaired night vision, infertility, rash of eyes mouth nose and anus.
