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Step 1 AB > Vitamins > Flashcards

Vitamins Flashcards

1
Q

B1 functions (think ATP)

A

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

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2
Q

B1 deficiency causes:

A
  1. Impaired glucose breakdown –> ATP depletion worsened by glucose infusion (highly aerobic tissues affected first) –> Wernicke Korsakoff syndrome and beriberi
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3
Q

B2 functions

A

Riboflavin used in dehydrogenase reactions

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

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4
Q

B2 Deficiency

A

Cheilosis (inflammation of lips, mouth)

Corneal vascularization

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5
Q

B3 functions

A

Niacin –> constituent of NAD+, NADP+

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

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6
Q

What is Niacin derived from?

A

Tryptophan

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7
Q

Synthesis of Niacin (B3) requires what?

A

Vitamins B2 (Riboflavin) and B6 (Pyridoxine)

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8
Q

B3 deficiency

A

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

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9
Q

Which conditions/drugs should Niacin be used with caution?

A

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

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10
Q

Niacin toxicity

A

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

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11
Q

Function of B5

A

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

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12
Q

Deficiency of B5

A

Dermatitis, enteritis, alopecia, adrenal insufficiency

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13
Q

Vitamin B6 function

A

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

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14
Q

B6 deficiency

A

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

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15
Q

What can induce B6 deficiency?

A

Isoniazid and contraceptives

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16
Q

B7 function

A

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

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17
Q

Which reactions use B7 as cofactor?

A

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

18
Q

Causes of B7 deficiency

A

Excessive egg white ingestion

Antibiotics

19
Q

B9 function

A

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

20
Q

B9 deficiency

A

Macrocytic, megaloblastic anemia, glossitis

21
Q

Labs in B9 deficiency

A

Increased homocysteine

Normal methylmalonic acid levels

22
Q

Drugs that cause folate deficiency

A

Methotrexate
Sulfonamides
Phenytoin

23
Q

Function of B12

A

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

24
Q

Functions of Vitamin C

A

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

25
Q

Vitamin C can increase toxicity of what?

A

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

26
Q

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

A

D3; cholecalciferol is formed in the stratum basale

27
Q

Why is vitamin D excess seen in granulomatous diseases?

A

Epithelial macrophages cause increased activation of Vitamin D

28
Q

Tocopherol/Tocotrienol

A

Vitamin E

29
Q

Tocopherol function

A

Antioxidant that protects RBCs and membranes from free radical damage

30
Q

Vitamin E deficiency

A

Hemolytic anemia
Acanthocytosis
Muscle weakness
Posterior column and spinocerebellar tract demyelination

31
Q

What can be given with Warfarin to enhance anticoagulant effects?

A

Vitamin E (Tocopherol)

32
Q

Differential of posterior column and spinocerebellar tract demyelination

A

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
Q

Phytomenadione, Phylloquinone, Phytonadione

A

Vitamin K

34
Q

Function of Vitamin K

A

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

35
Q

Where is Vitamin K synthesized?

A

Made by intestinal flora

36
Q

Vitamin K deficiency

A

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

37
Q

Zinc function

A

Essential for MANY enzymes

38
Q

Zinc deficiency

A 
Delayed wound healing
Hypogonadism
Decreased adult hair
Dysgeusia
Anosmia
Acrodermatitis enteropathica
39
Q

Fomepizole

A

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

40
Q

Disulfiram

A

Inhibits aldehyde dehydrogenase (hangover symptoms)

41
Q

Which drugs cause Disulfiram like reaction?

A

Metronidazole
Procarbazine
Cephalosporins

42
Q

Ethanol effects at cellular level

A

Increases NADH/NAD ratio in liver, causing:

  • Pyruvate –> lactate (lactic acidosis)
  • Oxaloacetate –> malate (prevents gluconeogenesis –> fasting hypoglycemia)
  • Dihydroxyacetone phosphate –> glycerol 3 phosphate (hepatosteatosis)

Step 1 AB (29 decks)

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