Vitamins

Question 1

B1 (Thiamine)

Answer 1

Cofactor for dehydrogenase enzymes–

1) Pyruvate dehyrdrogenase: glycolysis to TCA cycle
2) a-ketoglutarate dehydrogenase
3) Transketolase (HMP shunt)
4) Branched-chain ketoacid dehydrogenase

Question 2

B1 (Thiamine) Deficiency

Answer 2

Found with malnutrition and alcoholism
Dx: Increase RBC transketolase activity following B1 admin
ATP depletion worsened by glucose
Aerobic tissues affected 1st (brain, heart)

Question 3

Wernicke-Korsakoff syndrome

Answer 3

Classic triad: confusion, opthalmoplegia, ataxia
Confabulation, personality change, memory loss (perm)
Damage to the medial dorsal nucleus of the thalamus, mammillary bodies.

Question 4

Beri Beri

Answer 4

Dry: Polyneuritis, symmetrical muscle wasting
Wet: High output cardiac failure (dilated CM), edema

Question 5

B2 (Riboflavin) Function & Deficiency

Answer 5

Component of FAD and FMN; Cofactor for redox reactions
Deficiency:
Cheilosis (inflammation of lips) “magenta tongue”
Corneal vascularization

Question 6

B3 (Niacin)

Answer 6

Component of NAD+, NADP-
Derived from Tryptophan
Synthesis requires B2 & B6
Used to lower VLDL, raise HDL

Question 7

B3 (Niacin) Deficiency & Excess

Answer 7

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

Question 8

B5 (Pantothenate) Function & Deficiency

Answer 8

Essential component of Coenzyme A & Fatty acid synthase

Defeciency: Dermatitis, Enteritis, Alopecia, Adrenal Insufficiency

Question 9

B6 (Pyridoxine)

Answer 9

Cofactor used in transamination, decarboxylation rxns, glycogen phosphorylase.
Synthesis of: Cystathionine, Heme, Niacin, Histamine, NT (5HT, E, NE, DA & GABA)

Question 10

B6 Deficiency

Answer 10

Inducible by INH and OCPs.

Results in: Convulsions, Hyperirritability, Peripheral Neuropathy, Sideroblastic anemias (2/2 impaired heme)

Question 11

B7 Function & Deficiency

Answer 11

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

Question 12

B9 (Folic Acid)

Answer 12

Converted to Tetrahydrofolate (THF) Coenzyme for methylation reactions
Important for synthesis of nitrogenous bases
Found in green vegies and absorbed in the jejunum.

Question 13

B9 (Folic Acid) Deficiency

Answer 13

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

Question 14

B12 (Cobalamin)

Answer 14

Cofactor for homocysteine methyltransferase AND methylmalonyl-CoA mutase
Found in animal products, synthesized by microorganisms

Question 15

B12 (Cobalamin) Deficiency

Answer 15

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

Question 16

A (Retinol)

Answer 16

Antioxidant
Visual pigments & Epithelial cell differentiation
Prevents squamous metaplasia
Treats: measles, AML-M3 & acne (topical)

Question 17

Vitamin A Deficiency & Excess

Answer 17

Deficiency:

• Night blindness (nyctalopia)
• Dry, scaly skin (xerosis cutis)
• Corneal Degeneration (keratomalacia)
• Dry eye (xeropthalmia)

Excess:

• Arthralgias
• Psedotumor cerebri
• Osteoporosis
• Teratogenic!

Question 18

Vitamin C (Ascorbic Acid)

Answer 18

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)

Question 19

Vitamin C (Ascorbic Acid) Deficiency & Excess

Answer 19

Deficiency (Scurvy): swollen gums, bruising, hemarthosis, anemia, poor wound healing, perifollicular/subperiosteal hemorrhage, “corkscrew” hair

Excess: N/V/D, fatigue, Ca Oxalate stones

Question 20

Vitamin D

Answer 20

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

Question 21

Vitamin D Deficiency & Excess

Answer 21

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)

Question 22

Vitamin E (Tocopherol) Function & Deficiency

Answer 22

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.

Question 23

Vitamin K Function & Deficiency

Answer 23

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)