Vitamins

Question 1

B1 functions (think ATP)

Answer 1

Thiamine pyrophosphate used as cofactor for:
Alpha ketoglutarate dehydrogenase
Transketolase
Pyruvate dehydrogenase

Question 2

B1 deficiency causes:

Answer 2

1. Impaired glucose breakdown –> ATP depletion worsened by glucose infusion (highly aerobic tissues affected first) –> Wernicke Korsakoff syndrome and beriberi

Question 3

B2 functions

Answer 3

Riboflavin used in dehydrogenase reactions

Component of flavors FAD and FMN used in redox reactions (Succinate dehydrogenase reaction in TCA cycle)

Question 4

B2 Deficiency

Answer 4

Cheilosis (inflammation of lips, mouth)

Corneal vascularization

Question 5

B3 functions

Answer 5

Niacin –> constituent of NAD+, NADP+

Used to treat dyslipidemia –> lowers levels of VLDL and raises levels of HDL

Question 6

What is Niacin derived from?

Answer 6

Tryptophan

Question 7

Synthesis of Niacin (B3) requires what?

Answer 7

Vitamins B2 (Riboflavin) and B6 (Pyridoxine)

Question 8

B3 deficiency

Answer 8

Pellagra (dermatitis, dementia, diarrhea)
Can be caused by Hartnup disease (no tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism) or Isoniazid (decreases vitamin B6)

Question 9

Which conditions/drugs should Niacin be used with caution?

Answer 9

Hypertensives –> Niacin has vasodilatory effects that potentiate anti-HTN drugs
Associated with insulin resistance (Diabetics)
Increases serum uric acid (Gout)

Question 10

Niacin toxicity

Answer 10

Facial flushing (from prostaglandin –> take aspirin to avoid)
Hyperglycemia
Hyperuricemia

Question 11

Function of B5

Answer 11

Pantothenic acid –> essential component of coenzyme A (Acetylation reactions) and fatty acid synthase

Question 12

Deficiency of B5

Answer 12

Dermatitis, enteritis, alopecia, adrenal insufficiency

Question 13

Vitamin B6 function

Answer 13

Pyridoxine –> cofactor used in transamination, decarboxylation reactions, glycogen phosphorylase
Synthesis of cystathionine, heme, niacin, histamine, serotonin, epinephrine, norepinephrine, dopamine, GABA

Question 14

B6 deficiency

Answer 14

Convulsions, hyper irritability, peripheral neuropathy (inducible by isoniazid and oral contraceptives), sideroblastic anemia due to impaired hemoglobin synthesis and iron excess

Question 15

What can induce B6 deficiency?

Answer 15

Isoniazid and contraceptives

Question 16

B7 function

Answer 16

Biotin –> cofactor for carboxyation enzymes (CO2 carrier) –> pyruvate carboxylase, acetyl coA carboxylase, propionyl coA carboxylase

Question 17

Which reactions use B7 as cofactor?

Answer 17

Pyruvate carboyxlase: pyruvate –> oxaloacetate
Acetyl CoA carboxylase: acetyl coA –> malonyl coA
Propionyl CoA carboxylase: propionylCoA —> methylmalonyl coA

Question 18

Causes of B7 deficiency

Answer 18

Excessive egg white ingestion

Antibiotics

Question 19

B9 function

Answer 19

Converted to tetrahydrofolic acid, a coenzyme for 1 carbon transfer/metylation reactions
Important for the synthesis of nitrogenous bases in DNA and RNA

Question 20

B9 deficiency

Answer 20

Macrocytic, megaloblastic anemia, glossitis

Question 21

Labs in B9 deficiency

Answer 21

Increased homocysteine

Normal methylmalonic acid levels

Question 22

Drugs that cause folate deficiency

Answer 22

Methotrexate
Sulfonamides
Phenytoin

Question 23

Function of B12

Answer 23

Cofactor for homocysteine methyltransferase that transfers CH3 groups as methylcobalamin (makes homocysteine into methionine)
Cofactor for methylmalonyl coA mutase (methylmalonyl coA –> succinyl coA)

Question 24

Functions of Vitamin C

Answer 24

Antioxidant
Facilitates iron absorption by reducing it to Fe2+
Hydroxylation of proline and lysine in collagen synthesis
Necessary for dopamine Beta hydroxylase

Question 25

Vitamin C can increase toxicity of what?

Answer 25

Can increase risk of iron toxicity so it should be avoided in those with transfusions and hereditary hemochromatosis

Question 26

Which form of Vitamin D is formed in sun exposed skin?

Answer 26

D3; cholecalciferol is formed in the stratum basale

Question 27

Why is vitamin D excess seen in granulomatous diseases?

Answer 27

Epithelial macrophages cause increased activation of Vitamin D

Question 28

Tocopherol/Tocotrienol

Answer 28

Vitamin E

Question 29

Tocopherol function

Answer 29

Antioxidant that protects RBCs and membranes from free radical damage

Question 30

Vitamin E deficiency

Answer 30

Hemolytic anemia Acanthocytosis Muscle weakness Posterior column and spinocerebellar tract demyelination

Question 31

What can be given with Warfarin to enhance anticoagulant effects?

Answer 31

Vitamin E (Tocopherol)

Question 32

Differential of posterior column and spinocerebellar tract demyelination

Answer 32

Vitamin E deficiency - WITHOUT megaloblastic anemia, hypersegmented neutrophils or increased methylmalonic acid levels Vitamin B12 deficiency - Megaloblastic anemia, hypersegmented neutrophils and increased methylmalonic acid

Question 33

Phytomenadione, Phylloquinone, Phytonadione

Answer 33

Vitamin K

Question 34

Function of Vitamin K

Answer 34

Cofactor for gamma carboxylation of glutamic acid resides on proteins required for blood clotting

Question 35

Where is Vitamin K synthesized?

Answer 35

Made by intestinal flora

Question 36

Vitamin K deficiency

Answer 36

Neonatal hemorrhage with increased PT and PTT but normal bleeding time (or after prolonged use of broad spectrum Abx or Phenytoin)

Question 37

Zinc function

Answer 37

Essential for MANY enzymes

Question 38

Zinc deficiency

Answer 38

``` Delayed wound healing Hypogonadism Decreased adult hair Dysgeusia Anosmia Acrodermatitis enteropathica ```

Question 39

Fomepizole

Answer 39

Inhibits alcohol dehydrogenase Antidote for ethylene glycol or methanol poisoning (Normally ethylene glycol --> oxalic acid, methanol --> formaldehyde)

Question 40

Disulfiram

Answer 40

Inhibits aldehyde dehydrogenase (hangover symptoms)

Question 41

Which drugs cause Disulfiram like reaction?

Answer 41

Metronidazole Procarbazine Cephalosporins

Question 42

Ethanol effects at cellular level

Answer 42

Increases NADH/NAD ratio in liver, causing: - Pyruvate --> lactate (lactic acidosis) - Oxaloacetate --> malate (prevents gluconeogenesis --> fasting hypoglycemia) - Dihydroxyacetone phosphate --> glycerol 3 phosphate (hepatosteatosis)