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0. Step Ia > Biochem - Nutrition/Vitamins > Flashcards

Biochem - Nutrition/Vitamins Flashcards

1
Q

Vitamin B1 function

A

THIAMINE cofactor in

  • Pyruvate dehydrogenase (links glycolysis to TCA cycle)
  • α-ketoglutarate dehydrogenase (TCA cycle)
  • Transketolase (HMP shunt)
  • Branched-chain ketoacid dehydrogenaseATP
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1
Q

confusion, ophthalmoplegia, ataxia

A

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)

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1
Q

Dermatitis, enteritis, alopecia, adrenal insufficiency.

A

B5 is “pento”thenate

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1
Q

cobalamin deficiency can cause these 4 sx:

A
  • Macrocytic, megaloblastic anemia
  • hypersegmented PMNs
  • paresthesias
  • subacute combined degeneration of dorsal columns, lateral corticospinal tracts, and spinocerebellar tracts) due to abnormal myelin.
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2
Q

Marasmus

A

energy malnutrition, muscle wasting

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3
Q

outcomes of Vitamin A deficiency 5

A
  • Night blindness (nyctalopia)
  • dry, scaly skin (xerosis cutis)
  • alopecia
  • corneal degeneration (keratomalacia)
  • immune suppression.
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4
Q

polyneuritis, symmetrical muscle wasting.

A

Dry Beriberi, Thiamine deficiency

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4
Q

pathophysiology of giving glucose to a vitamin B1 deficient patient

A

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!

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5
Q

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

A

B6 (pyridoxine)

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6
Q

3 supplements you must give to a breast-fed neonate

A

1) vitamin D - promote intestinal absorption of Ca and bone mineralization
2) Vitamin K - prevent bleeding diathesis
3) Fe (prevent IDA)

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7
Q

vitamin B12 (cobalamin)

function?

outcomes of deficiency?

possible causes of deficiency?

diagnosed by?

A
  • 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
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7
Q

vitamin E

function

how deficiency presents

A

fat-soluble

function: antioxidant for erythrocytes
deficiency: hemolytic anemia, neuropathy

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7
Q

wet beriberi

A

high-output cardiac failure due to thiamine deficiency

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7
Q

thiamine - which vitamin?

A

B1

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7
Q

Vitamin B1 deficiency

A

Wernicke-Korsakoff syndrome and beriberi (Ber1Ber1)

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7
Q

treatment of cobalamin deficiency with folic acid results in

A

subacute combined degeneration of dorsal columns.

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7
Q

causes of calcium oxalate nephrolithiasis?

common presentation?

trmt?

A

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.

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8
Q

Folate - which vitamin?

A

B9

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9
Q

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

A

B6 ∆

Convulsions

Hyperirritability

Peripheral neuropathy

Sideroblastic anemias (impaired hemoglobin synthesis and iron excess)

B3 deficiency -> pellagra

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10
Q

zinc

function?

deficiency?

A

function: widespread, transcription factors
deficiency: metallic taste, delayed wound healing, hypogonadism, acrodermatitis enteropathica

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10
Q

Niacin is used to treat:

A

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

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10
Q

storage pool of folic acid vs storage pool of cobalamin?

A

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

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

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11
Q

Vitamin A excess - 6

A
  • Teratogen
  • Skin ∆s (scaliness)
  • alopecia
  • cerebral edema “pseudotumor cerebri”
  • osteoporosis
  • hepatic abnormalities
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11
Q

Diarrhea

Dementia (also hallucinations)

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

A

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

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12
Q

vitamin B3 (niacin)

function

causes of deficiency - 3

how deficiency presents

excess

A
  • 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
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13
Q

Niacin

derived from:

requires these two factors to form:

forms these two factors

A

derived from trypotophan

requires B2 and B6

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

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14
Q

biotin - which vitamin?

A

B7

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16
Q

Folic acid deficiency can be caused by these Rx

A

phenytoin, sulfonamides, methotrexate

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17
Q

vitamin B9 (folic acid)

function?

3 outcomes of deficiency?

causes of deficiency? 4

A

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

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19
Q

3 causes of vitamin K deficiency:

A
  • warfarin
  • neonates (sterile intestines - remember Vit K is made by intestinal flora)
  • Antibiotic use (kills off intestinal flora)
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19
Q

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

A

Marasmus = Muscle wasting.

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21
Q

vitamin B1 (thiamine)

function?

deficiency?

A

function: cofactor for alpha-ketoglutarate DH, transketolase, pyruvate DH, branched-chain amino acid DH
deficiency: wet + dry beriberi, Wernicke-Korsakoff

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23
Q

folic acid is initially converted into:

A

THF (a coenzyme required to convert homocysteine into methionine)

24
Q

vitamin B2 (riboflavin)

function

how deficiency presents

A

function: cofactor for FADH2 (oxidation and reduction)
deficiency: cheilosis, corneal vascularization

25
Q

Folic acid deficiency can cause these 3 sx and labs

A

Macrocytic, megaloblastic anemia

hypersegmented PMNs

Glossitis

increased Homocystine, normal MMA

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

27
Q

Essential component of coenzyme A and fatty acid synthase.

A

Vitamin B5 (pantothenate)

27
Q

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

A

Vitamin E deficiency (tocopherol/tocotrienol)

29
Q

vitamin B6 (pyridoxine)

A

function:

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

deficiency: peripheral neuropathy, sideroblastic anemia

30
Q

niacin - which vitamin?

A

B3

32
Q

labs of cobalamin deficiency

A

incr. serum homocysteine AND methylmalonic acid levels.

33
Q

drug for alcoholics to take to decrease intake

A

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

35
Q

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

A

Wet beriberi due to thiamine B1 deficiency

37
Q

pantothenic acid - which vitamin?

A

B5

38
Q

eating too much raw eggs will cause deficiency in this

A

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

39
Q

vitamin B7 (biotin)

function

deficiency

A

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
Q

dry beriberi

A

polyneuritis and muscle wasting

due to thiamine deficiency

42
Q

cobalamin deficiency caused by: 4

A

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
Q

ascorbic acid - which vitamin?

A

Vitamin C

44
Q

one malignancy that causes increase vitamin D?

A

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

46
Q

retinol - which vitamin?

A

Vitamin A

47
Q

B2 forms these two factors:

A

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

48
Q

vitamin K

function

deficiency

causes of deficiency 3

A

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
Q

Delayed wound healing

hypogonadism

decreased adult hair (axillary, facial, pubic)

dysgeusia

anosmia

acrodermatitis enteropathica

A

zinc deficiency

50
Q

vitamin D

function?

deficiency?

excess?

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

A

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
Q

Excess niacin cause these 3 sx

A
  • Facial flushing (induced by prostaglandins, not histamine)
  • hyperglycemia
  • hyperuricemia
52
Q

Folic acid deficiency can cause these labs

A

incr. homocysteine

normal methylmalonic acid

53
Q

Vitamin A can be used to treat these 2 diseases

A

measles AML, subtype 3

54
Q

vitamin A (retinol)

function

deficiency

excess

can be used to treat

A

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
Q

3 causes of niacin deficiency?

2 outcomes?

A

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
Q

2 functions of retinol (Vit A)?

A
  • antioxidant- constituent of rods in retina- req’d for differentiation of epithelial cells –> pancreatic cells, mucus-secreting cells
  • prevents squamous metaplasia
58
Q

small child with swollen belly

A

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

59
Q

Vitamin D deficiency in children vs adults vs both

A

children: rickets (bone pain and deformity)
adults: osteomalacia (bone pain and muscle weakness)
both: hypocalcemic tetany

60
Q

Vitamin E function?

A

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

E is for Erythrocytes.Can enhance anticoagulant effects of warfarin

62
Q

Patient with cheilosis & corneal vascularization

A

B2 deficiency (riboflavin)

63
Q

How do difference B12 from Vitamin E deficiency?

A

Neurological presentation may appear similar to vitamin B12 deficiency but without

  • megaloblastic anemia
  • hypersegmented neutrophils
  • increased serum methylmalonic acid levels.
64
Q

vitamin C (ascorbic acid)

function

how deficiency presents

how excess presents

A
  • function: antioxidant, collagen synthesis, NE synthesis
  • deficiency: scurvy
  • excess: GI symptoms, iron toxicity
65
Q

this supplementation decreases risk of neural tube defects

A

folic acid

66
Q

Sx of vitamin D excess?

A

Hypercalcemia, hypercalciuria, loss of appetite, stupor

67
Q

vitamin B5 (pantothenate)

function?

deficiency?

A

function: part of CoA and fatty acid synthase
deficiency: dermatitis, alopecia, adrenal insufficiency

68
Q

How to diagnose B1 deficiency?

A

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

70
Q

5 symptoms of B6 deficiency

A
  • Convulsions
  • Hyperirritability
  • Peripheral neuropathy
  • Sideroblastic anemias (impaired hemoglobin synthesis and iron excess)
  • according to Uworld: also seborrheic dermatitis, glossitis
71
Q

cobalmin - which vitamin?

A

B12

72
Q

riboflavin - which vitamin?

A

B2

73
Q

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

A

B-complex deficiencies (B5, B7)

74
Q

antidoate for methanol and ethylene glycol poisoning

A

fomepizole - inhibits alcohol dehydrogenase

75
Q

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

A

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

note: all the sx are related to collagen defects

77
Q

Vitamin C functions - 4

A
  • 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
Q

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

A

B12 and folate (stored in liver).

79
Q

pyridoxine - which vitamin?

A

B6

80
Q

Kwashiorkor presentation and cause

A

small child with swollen belly

protein malnutrition, edema, anemia, fatty liver

81
Q

how a patient with Wernicke-Korsakoff presents

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

0. Step Ia (28 decks)

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