Vitamin deficiencies and toxicities

Question 1

B1 - reactions

Answer 1

Thiamine - Pyruvate Dehydrogenase, alphaketoglutarate dehydrogenase, HMP shunt (transketolase), Branched-chain AA dehydrogenase

Question 2

B1 deficiency

Answer 2

ATP depletion - Dry and wet BeriBeri - heart and brain affected first; Wernicke= ophthalmoplegia, mental status, ataxia; Korsakoff- memory, confabulation, personality change

Question 3

B2 reaction and deficiency

Answer 3

FADH2, Riboflavin; Cheilosis and corneal vascularization

Question 4

B3 reaction

Answer 4

NAD, NADP; derived from tryptophan; synthesis requires B6

Question 5

B3 deficiency

Answer 5

pallagra (dementia, diarrhea, dermititis), aggression, confusion, ataxia; caused by Hartnup disease, INH use, Carcinoid

Question 6

B3 excess

Answer 6

Facial flushing that can be lessened by taking aspirin

Question 7

B5

Answer 7

Pentothenate; essential component of CoA (acyl transfers, TCA cycle, FA synthesis); deficiency dermatitis, enteritis, alopecia, ADRENAL INSUFFICIENCY (important in cholesterol synthesis)

Question 8

B6 reactions

Answer 8

Pyridoxine - glutamate to GABA, Glycine to Heme, Tryptophan to naicin, Homocystein to cysteine and SAM, Histidine to Histamine, Dopa to Dopamine,

Question 9

B6 shortage

Answer 9

convulsions (absence of gaba), sideroblastic anemia from inhibition of ALA synthase, peripheral neuropathy; deficiency inducible by INH or oral contraceptives

Question 10

B12 reactions

Answer 10

Homocystein to methionine and mehylalonyl-CoA to Succinyl CoA

Question 11

B12 deficiency

Answer 11

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

Question 12

Folic Acid function

Answer 12

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.

Question 13

Folic Acid Deficiency

Answer 13

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

Question 14

SAM

Answer 14

made from ATP and methionine. Methyl donor. Used for Epinepherine to epinepherine conversion; Used for methylation of 5’ guanosine cap during mRNA processing

Question 15

Biotin function

Answer 15

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)

Question 16

Biotin deficiency

Answer 16

Alopecia, gastroenteritis, Dermatitis; Caused by antibiotic use or excessive ingestion of RAW EGGS

Question 17

Vitamin C Function

Answer 17

Hydroxylation of Lysine and proline; absorption of Fe and maintenance of ferrous state; cofactor for dopamine to NE.

Question 18

Vit C defenciency

Answer 18

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)

Question 19

Excess of Vit C

Answer 19

Fe overload especially those at risk like people with hemochromatosis; Nausea, vomiting, idarrhea, fatigue, sleep problems

Question 20

Vitamin A function

Answer 20

Antioxidant; visual pigments (retinal); normal differentiation of specialized epithelium (prevents squamous metaplasia); used to treat measles and M3 AML; topical for wrinkles and acne

Question 21

Vit. A deficiency

Answer 21

Night blindness, dry skin, squamous metaplasia of conjunctiva (Bitot’s spots), xerophthalmia

Question 22

Vit. A excess

Answer 22

Arthralgias, fatigue, headache, SKIN CHANGES, sore throat, alopecia, teratogenic, increases in CSF pressure (can sometimes see cerebral edema through opthalmoscope)

Question 23

Vit. D excess

Answer 23

hypercalcemia, hypercalciuria. Abdominal pains. Seen in sarcoidosis because epithelioid cells

Question 24

Vit D.

Answer 24

Ergocalciferol (D2 - plants); Cholecalciferol (D3 - skin); 1,25-calcitrol (active)

Question 25

Vit E

Answer 25

alpha-tocopherol; antioxidant protects erythrocytes and membranes from free-radical damage

Question 26

Vit E deficiency

Answer 26

Fragility of erythrocytes, muscle weakness; Posterior column and spinocerebellar tract demyelination.

Question 27

Vit. K

Answer 27

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)

Question 28

Zinc deficiency

Answer 28

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.