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Flashcards in Vitamins Deck (42):
1

B1 functions (think ATP)

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

2

B1 deficiency causes:

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

3

B2 functions

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

4

B2 Deficiency

Cheilosis (inflammation of lips, mouth)
Corneal vascularization

5

B3 functions

Niacin --> constituent of NAD+, NADP+
Used to treat dyslipidemia --> lowers levels of VLDL and raises levels of HDL

6

What is Niacin derived from?

Tryptophan

7

Synthesis of Niacin (B3) requires what?

Vitamins B2 (Riboflavin) and B6 (Pyridoxine)

8

B3 deficiency

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

9

Which conditions/drugs should Niacin be used with caution?

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

10

Niacin toxicity

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

11

Function of B5

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

12

Deficiency of B5

Dermatitis, enteritis, alopecia, adrenal insufficiency

13

Vitamin B6 function

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

14

B6 deficiency

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

15

What can induce B6 deficiency?

Isoniazid and contraceptives

16

B7 function

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

17

Which reactions use B7 as cofactor?

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

18

Causes of B7 deficiency

Excessive egg white ingestion
Antibiotics

19

B9 function

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

20

B9 deficiency

Macrocytic, megaloblastic anemia, glossitis

21

Labs in B9 deficiency

Increased homocysteine
Normal methylmalonic acid levels

22

Drugs that cause folate deficiency

Methotrexate
Sulfonamides
Phenytoin

23

Function of B12

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

24

Functions of Vitamin C

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

25

Vitamin C can increase toxicity of what?

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

26

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

D3; cholecalciferol is formed in the stratum basale

27

Why is vitamin D excess seen in granulomatous diseases?

Epithelial macrophages cause increased activation of Vitamin D

28

Tocopherol/Tocotrienol

Vitamin E

29

Tocopherol function

Antioxidant that protects RBCs and membranes from free radical damage

30

Vitamin E deficiency

Hemolytic anemia
Acanthocytosis
Muscle weakness
Posterior column and spinocerebellar tract demyelination

31

What can be given with Warfarin to enhance anticoagulant effects?

Vitamin E (Tocopherol)

32

Differential of posterior column and spinocerebellar tract demyelination

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

33

Phytomenadione, Phylloquinone, Phytonadione

Vitamin K

34

Function of Vitamin K

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

35

Where is Vitamin K synthesized?

Made by intestinal flora

36

Vitamin K deficiency

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

37

Zinc function

Essential for MANY enzymes

38

Zinc deficiency

Delayed wound healing
Hypogonadism
Decreased adult hair
Dysgeusia
Anosmia
Acrodermatitis enteropathica

39

Fomepizole

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

40

Disulfiram

Inhibits aldehyde dehydrogenase (hangover symptoms)

41

Which drugs cause Disulfiram like reaction?

Metronidazole
Procarbazine
Cephalosporins

42

Ethanol effects at cellular level

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