Vitamin deficiencies and toxicities Flashcards Preview

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Flashcards in Vitamin deficiencies and toxicities Deck (28):

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



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



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.