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Flashcards in Biochem - Nutrition/Vitamins Deck (81):
1

Vitamin B1 function

THIAMINE cofactor in

  • Pyruvate dehydrogenase (links glycolysis to TCA cycle)
  • α-ketoglutarate dehydrogenase (TCA cycle)
  • Transketolase (HMP shunt)
  • Branched-chain ketoacid dehydrogenaseATP

1

confusion, ophthalmoplegia, ataxia

Wernicke-Korsakoff syndrome; also causes confabulation, personality change, permanent memory loss.

Causes damage to medial dorsal nucleus of thalamus, mammillary bodies (impt for recollective memory)

1

Dermatitis, enteritis, alopecia, adrenal insufficiency.

B5 is “pento”thenate

1

cobalamin deficiency can cause these 4 sx:

  • Macrocytic, megaloblastic anemia
  • hypersegmented PMNs
  • paresthesias
  • subacute combined degeneration of dorsal columns, lateral corticospinal tracts, and spinocerebellar tracts) due to abnormal myelin.

2

Marasmus

energy malnutrition, muscle wasting

3

outcomes of Vitamin A deficiency  5

  • Night blindness (nyctalopia)
  • dry, scaly skin (xerosis cutis)
  • alopecia
  • corneal degeneration (keratomalacia)
  • immune suppression.

4

polyneuritis, symmetrical muscle wasting.

Dry Beriberi, Thiamine deficiency

4

pathophysiology of giving glucose to a vitamin B1 deficient patient

If thiamine/B1 deficient patient is given glucose infusion first, pyruvate-->acetyl CoA won't work and all the substrates gets funneled to making lactate --> acidosis --> death.

Highly aerobic tissues (e.g., brain, heart) are affected first!

5

a cofactor used in transamination (e.g., ALT and AST), decarboxylation reactions, glycogen phosphorylase.

B6 (pyridoxine)

6

3 supplements you must give to a breast-fed neonate

1) vitamin D - promote intestinal absorption of Ca and bone mineralization

2) Vitamin K - prevent bleeding diathesis

3) Fe (prevent IDA)

7

vitamin B12 (cobalamin)

function?

outcomes of deficiency?

possible causes of deficiency?

diagnosed by?

 

  • function: cofactor that helps convert methylmalonyl-CoA to succinyl-CoA and homocysteine to methionine
  • deficiency: 
    • megaloblastic anemia (with hypersegmentation)
    • peripheral neuropathy
    • sub-acute degeneration of the spinal cord
    • increased MMA + homocystine levels
  • deficiency causes: rare due to liver stores
    • diphyllobothrium latum tapeworm
    • autoimmune (pernicious anemia)
    • anatomic (gastric bypass)
    • malabsorption (celiac disease), inflammatory (IBD)
  • deficiency diagnosed by Schilling test

7

vitamin E

function

how deficiency presents

fat-soluble

function: antioxidant for erythrocytes

deficiency: hemolytic anemia, neuropathy

7

wet beriberi

 

 

 

high-output cardiac failure due to thiamine deficiency

7

thiamine - which vitamin?

B1

7

Vitamin B1 deficiency

Wernicke-Korsakoff syndrome and beriberi (Ber1Ber1)

7

treatment of cobalamin deficiency with folic acid results in

subacute combined degeneration of dorsal columns.

7

causes of calcium oxalate nephrolithiasis?

common presentation?

trmt?

causes

  • ethylene glycol (antifreeze)
  • vitamin C abuse
  • Crohn disease (malabsorption of fats)

presentation: calcium oxalate stone in a patient with hypercalciuria and normocalcemia.

treatment: thiazides and citrate.

8

Folate - which vitamin?

B9

9

this vitamin deficiency is inducible by isoniazid and oral contraceptives, and it causes these symptoms

B6 ∆

Convulsions

Hyperirritability

Peripheral neuropathy

Sideroblastic anemias (impaired hemoglobin synthesis and iron excess)

B3 deficiency -> pellagra

10

zinc

function?

deficiency?

function: widespread, transcription factors

deficiency: metallic taste, delayed wound healing, hypogonadism, acrodermatitis enteropathica




 

10

Niacin is used to treat:

dyslipidemia; lowers levels of VLDL and raises levels of HDL.

10

storage pool of folic acid vs storage pool of cobalamin?

Folic acid (b9) = Small reserve pool stored primarily in the liver.

Cobalamin (b12) = large reserve pool (several years) stored primarily in the liver

11

Vitamin A excess - 6

  • Teratogen
  • Skin ∆s (scaliness)
  • alopecia
  • cerebral edema "pseudotumor cerebri"
  • osteoporosis
  • hepatic abnormalities

11

Diarrhea

Dementia (also hallucinations)

Dermatitis (casal necklace or hyperpigmentation of sun-exposed limbs)

Pellagra (vitamin B3 deficiency" The 3 D’s of B3

12

vitamin B3 (niacin)

function

causes of deficiency - 3

how deficiency presents

excess

  • function: part of NAD+ and NADP+, made from Trp, requires B6 to be synthesized
  • deficiency caused by
    • associated with Hartnup disease
    • carcinoid syndrome
    • INH use in tuberculosis
  • presentation: 3D's diarrhea, dermatitis, dementia (pellagra)
  • excess: hot flashes, facial flushing

13

Niacin

derived from:

requires these two factors to form:

forms these two factors

derived from trypotophan

requires B2 and B6

forms NAD+, NADP+ (used in redox reactions)

14

biotin - which vitamin?

B7

16

Folic acid deficiency can be caused by these Rx

phenytoin, sulfonamides, methotrexate

17

vitamin B9 (folic acid)

function?

3 outcomes of deficiency?

causes of deficiency? 4

function: converted to THF and used in DNA/RNA synthesis

deficiency results in: 

  • intrauterine neural tube defects
  • macrocytic anemia (with hypersegmentation)
  • increased homocystine levels

deficiency caused by: MTX, TMP-SMX, phenytoin, alcoholics and pregnancy

 

19

3 causes of vitamin K deficiency:

  • warfarin
  • neonates (sterile intestines - remember Vit K is made by intestinal flora)
  • Antibiotic use (kills off intestinal flora)

19

Total calorie malnutrition resulting in tissue and muscle wasting, loss of subcutaneous fat, and variable edema.

Marasmus = Muscle wasting.

21

vitamin B1 (thiamine)

function?

deficiency?

function: cofactor for alpha-ketoglutarate DH, transketolase, pyruvate DH, branched-chain amino acid DH

deficiency: wet + dry beriberi, Wernicke-Korsakoff









 

23

folic acid is initially converted into:

THF (a coenzyme required to convert homocysteine into methionine)

24

vitamin B2 (riboflavin)

function

how deficiency presents

function: cofactor for FADH2 (oxidation and reduction)

deficiency: cheilosis, corneal vascularization

25

Folic acid deficiency can cause these 3 sx and labs

Macrocytic, megaloblastic anemia

hypersegmented PMNs

Glossitis

increased Homocystine, normal MMA

NO neurologic symptoms (as opposed to vitamin B12 deficiency).

27

Essential component of coenzyme A and fatty acid synthase.

Vitamin B5 (pantothenate)

27

Hemolytic anemia, acanthocytosis, muscle weakness, posterior column and spinocerebellar tract demyelination.

Vitamin E deficiency (tocopherol/tocotrienol)

29

vitamin B6 (pyridoxine)

function:

  • cofactor in transamination, decarboxylation, glycogen phosphorylase
  • synthesis of heme, histamine, niacin, 5-HT, EPI, NE, GABA

deficiency: peripheral neuropathy, sideroblastic anemia
 

30

niacin - which vitamin?

B3

32

labs of cobalamin deficiency

incr. serum homocysteine AND methylmalonic acid levels.

33

drug for alcoholics to take to decrease intake

Disulfiram - inhibits acetaldehyde dehydrogenase (acetaldehyde accumulates, contributing to instant hangover symptoms)

35

high-output cardiac failure (dilated cardiomyopathy), edema.

Wet beriberi due to thiamine B1 deficiency

37

pantothenic acid - which vitamin?

B5

38

eating too much raw eggs will cause deficiency in this

B7 deficiency "Avidin in egg whites avidly binds biotin.”

39

vitamin B7 (biotin)

function

deficiency

function: cofactor for carboxylation (adds 1 carbon) in pyruvate carboxylase, acetyl-CoA carboxylase, and propionyl-CoA carboxylase

deficiency: dermatitis, alopecia, enteritis, associated with raw egg ingestion




 

41

dry beriberi

polyneuritis and muscle wasting

due to thiamine deficiency

42

cobalamin deficiency caused by: 4 

1) insufficient intake (veganism)

2) malabsorption (sprue, enteritis, diphyllobothrium latum)

3) lack of IF (pernicious anemia, bypass surgery)

4) absence of terminal ileum (Crohn disease, resection).

43

ascorbic acid - which vitamin?

Vitamin C

44

one malignancy that causes increase vitamin D?

Sarcoidosis (incr. activation of vitamin D by epithelioid macrophages).

46

retinol - which vitamin?

Vitamin A

47

B2 forms these two factors:

FAD and FMN are derived from riboFlavin (B2 = 2 ATP).

48

vitamin K

function

deficiency

causes of deficiency 3

fat-soluble

function: catalyses gamma-carboxylation → synthesis of clotting factors (2, 7, 9, 10, C, S)

deficiency: neonatal bleeding (must give vitamin K IM shot at birth)

causes of deficiency:

  • abx use (synthesized by intestinal flora)
  • warfarin (coumadin) acts as an antagonist to create a functional deficiency
  • neonates

49

Delayed wound healing

hypogonadism

decreased adult hair (axillary, facial, pubic)

dysgeusia

anosmia

acrodermatitis enteropathica

zinc deficiency

50

vitamin D

function?

deficiency?

excess?

excess production is related to this one d/o! (HIGH YIELD POINT)

fat-soluble

function: absorption of Ca and Phos, bone mineralizatoin

deficiency: 

  • rickets (children)
  • osteomalacia (adults)
  • hypocalcemia (can lead to 2ndary hyperparathyroidism)

excess: 

  • hypercalcemia → hypercalciuria → nephrolithiasis
  • causes
    • associated with granulomatous inflammation due to increased activity of 1-alpha hydroxylase by macrophages (e.g. sarcoidosis, tuberculosis)

 

51

Excess niacin cause these 3 sx

  • Facial flushing (induced by prostaglandins, not histamine)
  • hyperglycemia
  • hyperuricemia

52

Folic acid deficiency can cause these labs

incr. homocysteine

normal methylmalonic acid

53

Vitamin A can be used to treat these 2 diseases

measles AML, subtype 3

54

vitamin A (retinol)

function

deficiency

excess

can be used to treat

fat-soluble

function: antioxidant, prevents squamous metaplasia

deficiency: night blindness

excess: teratogenic, idiopathic intracranial hypertension (pseudotumor cerebri), alopecia

treats: acne and APL (AML type M3)

 

54

3 causes of niacin deficiency?

2 outcomes?

1) Hartnup disease (decr. tryptophan absorption)

2) malignant carcinoid syndrome (incr. tryptophan metabolism to make serotonin)

3) isoniazid (decr. vitamin B6).

outcomes: Glossitis + Pellagra

56

2 functions of retinol (Vit A)?

  • antioxidant- constituent of rods in retina- req'd for differentiation of epithelial cells --> pancreatic cells, mucus-secreting cells
  • prevents squamous metaplasia

58

small child with swollen belly

Kwashiorkor - Protein malnutrition resulting in skin lesions, edema, liver malfunction (fatty change due to decreased apolipoprotein synthesis).

59

Vitamin D deficiency in children vs adults vs both

children: rickets (bone pain and deformity)

adults: osteomalacia (bone pain and muscle weakness)

both: hypocalcemic tetany

60

Vitamin E function?

Antioxidant (protects erythrocytes and membranes from free radical damage).

E is for Erythrocytes.Can enhance anticoagulant effects of warfarin

62

Patient with cheilosis & corneal vascularization

B2 deficiency (riboflavin)

63

How do difference B12 from Vitamin E deficiency?

Neurological presentation may appear similar to vitamin B12 deficiency but without

  • megaloblastic anemia
  • hypersegmented neutrophils
  • increased serum methylmalonic acid levels.

64

vitamin C (ascorbic acid)

function

how deficiency presents

how excess presents

  • function: antioxidant, collagen synthesis, NE synthesis
  • deficiency: scurvy
  • excess: GI symptoms, iron toxicity

65

this supplementation decreases risk of neural tube defects

folic acid

66

Sx of vitamin D excess?

Hypercalcemia, hypercalciuria, loss of appetite, stupor

67

vitamin B5 (pantothenate)

function?

deficiency?

function: part of CoA and fatty acid synthase

deficiency: dermatitis, alopecia, adrenal insufficiency




 

68

How to diagnose B1 deficiency?

measure increase in RBC transketolase activity following vitamin B1/thiamine administration.

70

5 symptoms of B6 deficiency

  • Convulsions
  • Hyperirritability
  • Peripheral neuropathy
  • Sideroblastic anemias (impaired hemoglobin synthesis and iron excess)
  • according to Uworld: also seborrheic dermatitis, glossitis

71

cobalmin - which vitamin?

B12

72

riboflavin - which vitamin?

B2

73

If you see these dermatitis, alopecia, enteritis, you should think of:

B-complex deficiencies (B5, B7)

74

antidoate for methanol and ethylene glycol poisoning

fomepizole - inhibits alcohol dehydrogenase

75

swollen gums, bruising, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages, “corkscrew” hair.

Vitamin C deficiency causes sCurvy due to a Collagen synthesis defect.

note: all the sx are related to collagen defects

77

Vitamin C functions - 4

  • Antioxidant.
  • Facilitates iron absorption by reducing it to Fe2+ state.
  • Necessary for hydroxylation of proline and lysine in collagen synthesis.
  • Necessary for dopamine β-hydroxylase, which converts dopamine to NE.

78

all vitamins wash out from the body except for these two:

B12 and folate (stored in liver).

79

pyridoxine - which vitamin?

B6

80

Kwashiorkor presentation and cause

small child with swollen belly

protein malnutrition, edema, anemia, fatty liver


 

81

how a patient with Wernicke-Korsakoff presents

  • ataxia, memory loss, confabulation, opthalmoplegia, confusion
  • damaged mamillary bodies