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Step 1 review cards > Biochemistry: Nutrition > Flashcards

Biochemistry: Nutrition Flashcards

1
Q

What vitamins are fat soluble?

A

A/D/E/K

Absorption is 100% dependent on ileum and the pancreas (disorders in either can cause fat soluble vitamin deficiencies)

Toxicity is less common than water soluble toxicity

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2
Q

What vitamins are water soluble?

A

Thiamine (B1)

Riboflavin (B2)

Niacin (B3)

Pantothenic acid (B5)

Pyridoxine (B6)

Biotin (B7)

Folate (B9)

Cobalamin (B12)

Ascorbic acid (vitamin C)

Easier to gain toxicity of OD

  • all wash out of system easily (can reverse toxicity easily) EXCEPT folate and cobalamin*
  • folate stays in liver for 3-4 months
  • cobalamin stays in liver 3-4 years
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3
Q

vitamin A (retinol/retinoic acid) function

A

Antioxidant

Generates retinol (helps with eye pigmentation and ability to see)

Prevents squamous cell metaplasia (cancer)

Helps epithelial tissue differentiate into mucus secreting cells

  • excess is used in treatment for APL and measles*
  • topical vitamin a (retinol) is used for acne sometimes*
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4
Q

Vitamin A (retinol/retinoic acid) deficiency effects

A

Night blindness

Dry scaly skin (xerosis cutis)

Bitot spots (keratin debris on conjunctiva)

Corneal degeneration

Immunosuppression

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5
Q

Vitamin A toxicity effects

A

Acute:
- nausea/vomiting/ blurry vision

Chronic

  • alopecia
  • dry skin
  • hepatic toxicity
  • intercranial HTN

is teratogenic (develops cleft palate and cardiac disfigurements)

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6
Q

Vitamin B1 (thiamine) function

A

Acts a cofactor for the following dehydrogenase reactions/enzymes:

  • Branched-chained ketoacid dehydrogenase
  • A-ketoglutarate dehydrogenase
  • Pyruvate dehydrogenase
  • Transketolase (HMP shunt pathway)

“Be APT”

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7
Q

Vitamin B1 (thiamine) deficiency

A

Impaired glucose breakdown and ATP formation
- gets worse with glucose infusion unless given thiamine first

Damages heart, brain, liver and kidney tissues first

diagnosis is made by increased RBC transketolase activity after administration of thiamine

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8
Q

Wet vs dry beriberi

A

both are precipitated via thiamine (vitamin B1) deficiencies

Dry:

  • polyneuropathy
  • symmetric muscle wasting

Wet:

  • cardiac damage
  • edema
  • heart failure
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9
Q

Wernicke’s encephalopathy

A

Acute life threatning condition brought on by thiamine deficiency
- made worse if giving glucose/sugar to patients with thiamine deficiency before the thiamine injection

Symtpoms:

  • neurologic issues
  • classic triad of:
    1) general confusion
    2) opthalmoplegia (paralysis of eye muscles)
    3) ataxia
  • treated via thiamine and glucose injections. If not treated, leads to korsakoff syndrome*
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10
Q

What is ataxia?

A

Neurological symptom that mimics drunken behaviors:

  • slurred speech
  • incoordination
  • shuffling/staggered gate
  • falling over/ poor balance
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11
Q

Korsakoff syndrome

A

Chronic thiamine deficiency syndrome often proceeded by alcoholism
- is the evolved from of wernicke’s ( however you do not always need to get wernicke’s first to have korsakoff. Just all untreated cases of wernicke’s degrades to korsakoff)

Symptoms:

  • all symptoms of wernickes encephalopathy
  • confabulation (making up memories that didn’t actually happen)
  • personality changes
  • permanent memory loss
  • sometimes is called wernicke-korsakoff syndrome when the medial dorsal nucleus of the thalamus is damaged*
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12
Q

Vitamin B2 (riboflavin) function

A

Helps generate FAD and FMN molecules which are used in redox (reduction-oxidation) reactions
- “B2 generates 2 ATP”

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13
Q

Vitamin B2 (riboflavin) deficiency

A

Cheilosis (inflammation and scarring of the lips and corners of the mouth)

Corneal vascularization (chronic blood shot eyes)

“2 Cs of B2”

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14
Q

Vitamin B3 (niacin/nicotinic acid) function

A

Generates NAD/NADP molecules used in redox reactions

Naturally derived from tryptophan
requires B2 and B6 to generate naturally

often used in hyper-cholesterol (dyslipidemia) since it lowers VLDL and raises HDL

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15
Q

Vitamin B3 (niacin/nicotinic acid) deficiency

A

Glossitis (inflammation of the tongue)

Also generates pellagra which is the following three symptoms
- Diarrhea
- Dementia
- Dermatitis (around the C3/C4 dermatome)
“3D’s of vitamin B3”
* also hyperpigmentation of sun exposed limbs

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16
Q

Hartnup disease

A

Autosomal recessive disorder that results in a natural deficiency of tryptophan transporters in PCTs of renal system and enterocytes
- causes decreased reabsorption of vitamin B3 and natural conversation of tryptophan -> niacin

Generates pellagra symptoms

Treatment:

  • high protein diet
  • nicotinic acid supplements
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17
Q

Vitamin B3 toxicity

A

Leads to:

  • facial flushing
  • hyperglycemia
  • hyperuricemia
  • this is the only other time other than gout that podagra can form*
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18
Q

Vitamin B5 (Pantothenic acid) function

A

Essential to CoA production and FA synthesis

- CoA can not be produced without vitamin B5

19
Q

Vitamin B5 deficiency

A

Diffuse dermatitis

Enteritis

Alopecia

Adrenal insufficiency syndrome

20
Q

Vitamin B6 (pyridoxine) function

A

Functions to:

  • generate PLP cofactor for liver enzyme production and maintenance (ALT/AST)
  • synthesis of glutathione, histamine, and Heme groups
  • synthesis of neurotransmitters (NE/epinephrine/serotonin/dopamine/GABA)
21
Q

Vitamin B6 deficiency

A
  • can be triggered by over use of isoniazid and oral contraceptives*

Symptoms:

  • convulsions
  • hyper irritability
  • peripheral neuropathy
  • Sideroblastic anemia
22
Q

Vitamin B7 (biotin) function

A

Cofactor for most carboxylation enzymes/reactions

23
Q

Vitamin B7 (biotin) deficiency

A

often caused by overconsumption of raw eggs (contains avidin which irreversibly binds biotin) and chronic use of antibiotics

Symptoms:

  • dermatitis
  • enteritis
  • alopecia

“Avidin avidly binds biotin”

24
Q

Vitamin B9 (folate) function

A

Synthesizes THF (tetrahydrofolate acid) which is a cofactor in methylation/carbon transfer reactions

Very important in synthesis of purines and pyrimidines found in DNA/RNA

25
Q

Vitamin B9 (folate) deficiency

A

Macrocytic and/or megaloblastic anemia

Hypersegmented PMN cells*

increased serum methylmalonic acid levels

Glossitis

Teratogenic (increases chances of neural tube defects) MUST give supplements to mother 1 month prior to contraception and during pregnancy (first 9 months)

NO neurological symptoms
- B12 has the same symptoms, but shows neurological symptoms

26
Q

Vitamin B12 (cobalamin) function

A

Cofactor for methionine synthase and methylation of DNA synthesis

27
Q

Vitamin B12 (cobalamin) deficiency

A
  • usually only occurs in the presence of malabsorption or lack of the terminal ileum. Can also be alcoholic or having gastric bypass surgery*

Symptoms:

  • exact same hematologists issues as vitamin B 9 deficiency*
  • paresthesia and subacute degeneration of dorsal medial lateral lemniscus pathway
  • degeneration fo spinocerebellar tracts
  • chronic deficiency = diffuse irreversible nerve damage
  • increased serum methylmalonic acid levels

folate supplements can mask hematological issues, but not the neurological issues

28
Q

Vitamin C (ascorbic acid) function

A

Antioxidant that also facilitates iron absorption by reducing iron to ferrous (Fe2+) state. (ferric is Fe3+)

Needed for hydroxylation reactions of proline and lysine in collagen synthesis as well

Needed for dopamine -> NE conversion as well

as an ancillary treatment for methemoglobinemia, give vitamin C supplements

29
Q

Vitamin C (ascorbic acid) deficiency

A

Scurvy

  • swollen gums
  • easy brushing
  • diffuse petechiae
  • hemarthrosis
  • anemia
  • corkscrew-like hair

weakened immune systems

30
Q

Vitamin C (ascorbic acid) excess

A

Nausea/vomiting

Fatigue

Calcium oxalate neprholithiasis

  • Increased iron toxicity if occurring in conjunction*
  • especially in hemachromotosis patients
31
Q

Vitamin D function

A

can be D3 (version found in sunlight, Milk and fish) or D2 ( from plants and yeasts). Irrelevant though since both are converted into 1,25-OH (calcitriol)

Increased intestinal absorption Of calcium and phosphate ( for bone growth)

Increases bone resorption and mineralization

32
Q

How is vitamin D levels regulated?

A

PTH and parathyroid glands

1,25-OH natural feedback loop

33
Q

Vitamin D deficiency

A

Rickets (Bow-legs)= children

Osteomalacia = adults
- generalized bone pain and muscle weakness

Hypocalcemia tetany

  • causes are usually malabsorption, decreased sun exposure, poor diet, chronic kidney disease and liver disease*
  • the deficiency is exacerbated in premature births as well
34
Q

Vitamin D excess

A

Hypercalcemia and Uria

Loss of appetite

Stupor

common in granulomatosis diseases

35
Q

Vitamin E (tocopherol/tocotrienol) function

A

Antioxidant for RBCs and membranes

36
Q

Vitamin E (tocopherol/tocotrienol) deficiency

A

Same neurological issues as B12 deficiency (demyelination of posterior columns), but does NOT show hematolgocial disorders seen in B9/12 (segmented PMNs, megaloblastic/sideroblastic anemia)

Acanthocytosis (spur-like cells)

Generalized muscle weakness

There is NO increase in serum methylmalonic acid

37
Q

Vitamin E (tocopherol/tocotrienol) excess

A

Enterocolitis in infants
- really the only issue associated, doesnt really hurt adults directly

  • can induce malabsorption of vitamin K and its metabolism*
  • this exacerbates warfarin’s effect, so must monitor in patients with warfarin
38
Q

Vitamin K (adione/quinone) function

A

Activates epoxide reductase which acts as a cofactor for gamma-carboxylation of glutamic acid residues on factors 1/7/9/10 and proteins C/S
- used for proper blood clotting

  • is naturally synthesized in gut flora*
39
Q

Vitamin K (adione/quinone) deficiency

A

Lowers ability to clot.
- in infants the bleeding time is NOT increased but PTT and PT times are (neonates do not have sterile intestines so they cannot naturally synthesis vitamin K)

  • often occurs after prolonged use of broad-spectrum antibiotics

is not in breast milk so neonates are often given vitamin K injections at birth to prevent neonate hemorrhages as a complication of birth

40
Q

Zinc function

A

Found in almost all enzymes and is required for them to work

Especially useful in the immune system and formation of transcription factor motif

41
Q

Zinc deficiency

A

Delayed wound healing

Suppressed immunity

Male hypogodanism

Decreases male adult facial hair

Dysgeusia (impaired or inability to taste)

Anosmia (impaired or inability to smell)

increases chances of alcoholic cirrhosis of the liver

Very common natural in patients with Acrodermatitis enteropathica*

42
Q

Acrodermatitis enteropathica

A

Autosomal recessive disorder that causes defective proteins used in binding zinc properly
- leads to malabsorption and weakened resorption of zinc

Symptoms:

  • periorificial dermatitis (dermatitis around the anus, eyes and mouth)
  • alopecia
  • diarrhea

Treatment:

  • give zinc supplements
  • use drug Diodoquin (iodoquinol) to treat alopecia and dermatitis
43
Q

Kwashiorkor syndrome

A

Protein malnutrition that results in:

  • skin lesions and diffuse edema (due to low plasma oncotic pressure)
  • liver malfunction and fatty liver
  • swollen abdomen
  • anemia

“Kwashiorkor results from proteins deficient MEALS”

  • Malnutiriton
  • Edema
  • Anemia
  • Liver is fatty
  • Skin lesions
44
Q

Marasmus syndrome

A

Caloric malnutrition disorder
- all nutrient levels are above deficency levels

Symptoms:

  • wide spread muscle wasting
  • weight loss
  • chronic diarrhea
  • sunken eyes
  • poor fetal growth/development
  • ribs are clearly seen through skin

Step 1 review cards (24 decks)

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