Biochem Nutrition Deficiency/Tox

Question 1

Vitamin A

Answer 1

• Retinol
• Fat soluble
• Negative Acute Phase Reactant: Vit A will be lower in inflammatory state: check ESR or CRP
• Important in: vision, cornea, epithelial membranes
• Sources:
  1) Preformed/active (retinol) - liver, dairy, egg yolk
  2) Precursor/inactive (carotenoids) - yellow, orange, green veggies (spinach, carrots…)

Deficiency –> night blindness, xerophthalmia (dry cornea), Bitot’s spots (foamy spots), dry scaly skin

Toxicity (only with preformed): increased ICP, N/V, blurred vision, bone mineral loss (fx and osteoporosis), hepatic too (big liver), pseudo tumor cerebri, TEATROGENIC
Uses of Vit A: measles, acne, APML

Question 2

Vitamin D

Answer 2

• Fat soluble
• Function: intestinal absorption of Ca, P, and increase bone mineralization

D2 = ergocalciferol - from plants
D3 = cholecalciferol - milk and sun light (converts D2--> D3)

25-OH D3 = storage form - Liver
1,25-OH = calcitriol = active form - Kidney

Deficiency –> RICKETS = failure to calcify bones –> osteomalacia (bone pain) + deformity (rib rosary, bowed legs, widened metaphysics (wrists), fx, adult osteoporosis, Labs: dec Ca + P, increased alk Phos

Toxicity: hypercalcemia, hypercalciuria, dec appetite. See in granulomatous dz (sarcoidosis)

Question 3

Vitamin E

Answer 3

-Fat soluble
Function: antioxidant (protect RBCs and membranes from free radical damage), free radical scavenger
From:
-Deficiency: Neuro degeneration (loss of DTRs, spinocerebellar ataxia, neuropathy), hemolytic anemia
-Causes of Deficiency: fat malabsorption, short gut, CF

Toxicity: coagulopaty (large doses of Vit E –> inhibit Vit K dependent coag factors)

Question 4

Vitamin K

Answer 4

-Fat Soluble
Function: carboxylation of coagulation factors and proteins II, VII, IX, X, C and S
Source: intestinal bacteria
Deficiency: increase coagulation times (PT/PTT), but nml bleeding time
-Hemorrhagic Dz of Newborn: Vit K is large mol with poor placental transport (doesn’t cross to baby well) and isn’t in breastmilk –> all newborns get IM Vit K

Question 5

Summary/Quick Associations

1) Vit A
2) Vit D
3) Vit E
4) Vit K
5) B1/Thiamine
6) B2/Riboflavin
7) B3/Niacin
8) B6/Pyridoxine
9) Folate/B9
10) B12/Cobalamin
11) Vit C - Acorbic Acid

Answer 5

1) Vit A –> eye and Skin
2) Vit D –> Rickets
3) Vit E –> Neuro (no DTRs) and Hemolytic Anemia, can inhibit Vit K
4) Vit K –> Anemia, Hemorrhagic Dz of Newborn
5) B1/Thiamin –> Dry/Wet Beriberi (neuro +/- CHF), Wernicke-Korsakoff (CAN),
6) B2/Riboflavin –> cheilosis, corneal vascularization, scrotal dermatitis
7) Niacin –> NAD/NADP, tx for dyslipidemia, PELLAGRA (symmetric sun rash, dementia, diarrhea, death), Carcinoid tumor, INH
8) B6/Pyridoxine –> cofactor, sideroblastic anemia, sz, peripheral neuropathy, INH and OCTs
9) Folate/B9 –> macrocyclic megaloblastic anemia, nml methylmalonic acid, no neuro sx, neural tube deficits
10) B12/Cobalamin –> microcytic megaloblastic anemia (pernicious anemia), high methylmalonic acid, + neuro sx
11) Vit C –> Scurvy

Question 6

B1/Thiamine

Answer 6

Function: TDP and TPP coenzymes important in cell metabolism
Sources: whole grains, pork, legumes, not found in polished/refined rice
Deficiency: impaired glucose breakdown –> ATP depletion
1) Dry Beriberi = neuro only –> peripheral neuropathy, foot drop
2) Wet Beriberi = neuro + cardiac –> dry beriberi + CHF, edema
3) Wernicke-Korsakoff = CAN (Confusion, Ataxia, Nystagmus/Opthalmoplegia) of Beer (see in alcoholics) - also get memory loss and confabulation, personality changes. Caused by damage to MAMILLARY BODIES

Question 7

B2/Riboflavin

Answer 7

Function: important in FAD and FMN coenzymes in TCA
Sources: liver, dairy (but UV light destroys B2), leafy greens

Deficiency –> Oral-Ocular-Genital Syndrome = CHEILOSIS (cracked lips) angular stomatitis (corner of mouth sores), increased vascularization of conjunctiva, and dermatitis (seborrheic and scrotal)

Question 8

B3/Niacin

Answer 8

Function: component of NAD and NADP (redox rxns),

• derived from Tryptophan - required B6 cofactor
• Niacin used to tx dyslipidemia (increase HDL and lowers VLDL)

Deficiency = PELLAGRA –> Dermatitis (symmetric scaly pattern, patchy hyper/hypopigmentation, worsened by sun/heat exposure), Dementia, Diarrhea
-Causes of deficiency: CORN meal based diet w/o lime, CARCINOID tumor metabolic shunting (tryptophan also precursor to serotonin so increased serotonin –> less tryptophan), TB TX with ISONIAZID (INH)

Toxicity –> flushing and peripheral vasodilation

Question 9

B6/Pyridoxine

Answer 9

Function: Cofactor for production of:

• dopa –> DA,
• tryptophan –> Niacin
• tryptophan –> Serotonin
• histidin –> Histamine,
• glycine –> Porphoryn (—> heme)
• glutamate –> GABA
• and PLP for transamination (i.e. AST, ALT)

Deficiency: sideroblastic anemia (can’t make porphyrn precursor to heme), sz/convulsions (decreased GABA)

• can be induced by ISONIAZID or oral contraceptives
• INH tox –> hepatotox with increased AST > ALT

Toxicity: neuro sx = peripheral neuropathy, ataxia

Question 10

Folate/B9

Answer 10

Hematopoietic (RBC synth)
Function: methyl donor, converted into THF (tetrahydrofolate)
Source: leafy green veggies, absorbed in jejunum
Deficiency: macrocyclic megaloblastic anemia (hyperhsegmented neutrophils), increased homocysteine but nil methylmalonic acid, no neuro sx
-Maternal deficiency –> cause neural tube defects (anacephaly, spina bifida)

Causes of Deficiency: drugs (phenytoin/dilantin, sulfonamide, methotrexate), unsupplemented goat milk (no breast milk), alcoholics (poor diet)

Question 11

B12/Cobalamin

Answer 11

Function: cofactor for homocysteine methyltransferase, metabolism of odd chain fatty acids
Source: animal products, have large reserve in body (liver)
Absorption: bind to intrinsic factor (secreted from gastric parietal cells), complex absorbed in distal ileum, into portal circulation
Deficiency: macrocytic, megaloblastic anemia with neuro sx (parenthesis, gait problems, subacute combined degeneration), increased homocysteine and increased methylmalonic acid
-causes: pernicious anemia (anti-IF antibodies), gastric atrophy (elderly), stomach or SB resection (short gut syndrome), vegan/vegetarian diet (decreased intake), breastfed infant of deficient mother (infant will be hypotonic, weak, developmentally delayed, poor feeder)

Question 12

Vitamin C = Ascorbic Acid

Answer 12

-Water soluble
Function: antioxidant, collagen synth, cofactor for dopamine –> NE

Deficiency = Scurvy –> defective collagen synth in basement membrane (petechia, bloody gums, anemia, bruising, poor wound healing, painful joints, corkscrew hair)