Rare, because vitamin K can be produced by bacteria in the GIT Hemorrhagic Disease of the Newborn (HDN) - presents as bleeding (including intracranial bleeds) - neonates at risk because of sterile GIT and low vitamin K content of breast milk

Vitamins Flashcards by Kringkring B

Absorption dependent on (terminal) ileum, bile and pancreas

Toxicity(not readily excredible) more common- ⬆️ intake leads to eventual storage in fatty tissues

Affected by Malabsorption Syndromes:

cystic fibrosis
celiac sprue
mineral oil intake

Fat-soluble vitamins

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Fat-soluble vitamins

Vitamin A

Vitamin D

Vitamin E

Vitamin K

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3 forms of VITAMIN A

Retinol (vitamin A alcohol) ➡️ gametogenesis

Retinal (vitamin A aldehyde) ➡️ vision

Retinoic acid (vitamin A acid) ➡️ growth regulators in epithelium

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Promote epithelial cell proliferation and differentiation

Storage form: retinyl esters

Transport form: retinol-binding protein (RBP)

Vitamin A

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Vitamin A deficiency

Nyctalopia (night blindness) earliest manifestation

Xerophthalmia: eye and corneal dryness

Impotence

Growth retardation

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Toxicity of vitamin A (hypervitaminosis A)

Hyperkeratosis

Hepatomegaly

Pseudotumor cerebri (h ICP)

Increased fractures

Teratogenic

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Derived cholesterol

Precursor: 7-DEHYDROCHOLESTEROL

Storage: 25-(OH) vitamin D3

Active form: 1,25-(OH)2 vitamin D3

Function: responds to hypocalcemia and PTH

End goal: ⬆️ calcium and ⬆️ PO4

⬆️ intestinal absorption of calcium
⬆️ bone resorption
⬆️ kidney reabsorption

Vitamin D

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3 forms of Vitamin D

Ergocalciferol: Vitamin D2, milk, plant sources

Cholecalciferol: Vitamin D3, skin, animal sources

Calcitriol: 1,25-(OH)2 Vitamin D3

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Hydroxylations of VITAMIN D

Vitamin D3 must be hydroxylated to become the active form. It undergoes a series of 2 hydroxylations:
1st- 25 hydroxylation ➡️ in the liver
2nd- 1 hydroxylation ➡️ in the kidney

(Anticipate vitamin D deficiency in CKD)

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Vitamin D deficiency

Rickets: in children only, before growth plate closes

Osteomalacia: in adults only, after growth plate closes

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Toxicity of Vitamin D (Hypervitaminosis D)

Most toxic vitamin

Hypercalcemia

Anorexia and nausea

Thirst

Stupor

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Effects of hypocalcemia (vitamin D)

Tetany and seizures

Chvostek’s sign

Trosseau’s sign

Long QT

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Effects of hypercalcemia (vitamin D)

Stones (urolithiasis)

Bones (pain, osteoporosis)

Abdominal groans (constipation, PUD, pancreatitis)

Psychic overtones (depression, anxiety, psc)

Short QT

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Antioxidant in the lipid phase

Protects membrane lipids from peroxidation

Prevents oxidation of LDL - ⬇️ atherogenesis

LEAST TOXIC

membrane stabilization prevents atherosclerosis prone to hemolysis - ⬇️ vitamin E

Vitamin E

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Vitamin E deficiency

RBC fragility

Neurological dysfunction (neuropathy)

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3 forms of Vitamin K

Phylloquinone - Vitamin K1

Menaquinone - Vitamin K2

Menadione - Synthetic

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Vitamin K deficiency

Rare, because vitamin K can be produced by bacteria in the GIT

Hemorrhagic Disease of the Newborn (HDN)

presents as bleeding (including intracranial bleeds)
neonates at risk because of sterile GIT and low vitamin K content of breast milk

Vitamin K toxicity

Jaundice + hemolytic anemia

Water-soluble Vitamins

Vitamin B1 (thiamine)

Vitamin B2 (riboflavin: FAD, FMN)

Vitamin B3 (niacin: NAD+)

Vitamin B5 (Pantothenic acid: CoA)

Vitamin B6 (Pyridoxine: pyridoxal phosphate)

Vitamin B12 (Cobalamin)

Vitamin C (Ascorbic acid)

Biotin

Folate

Generally non-toxic compared to the oil-solubles

excesses just wash out of the body in the urine
exceptions: VITAMIN B6 and B12

Water-soluble Vitamins

Active form: THIAMINE PYROPHOSPHATE (TPP)
( used as a cofactor in:
Pyruvate, a-ketoglutarate, and branched chain AA dehydrogenase
Transketolase reactions in the HMP shunt)

Vitamin B1 (Thiamine)

Vitamin B1 deficiency

Beriberi (dry and wet)

dry beriberi: dry = no heart failure (Polyneuritis, symmetrical muscle wasting)
wet beriberi: wet = with heart failure (High-output cardiac failure ▶️ dilated cardiomyopathy)

Wernicke-Korsakoff syndrome

Confusion

Loss of muscle coordination (ataxia)
- leg tremor

Vision changes
- abnormal eye movements (back and forth movement) NYSTAGMUS

double vision

Eye drooping

Wernicke’s encephalopathy

Inability to form new memories

Loss of memory can be severe

Making up stories (confabulation)

Seeing or hearing things that aren’t really there (hallucinations)

Korsakoff syndrome

Active form: FLAVIN MONONUCLEOTIDE (FMN), FLAVIN ADENINE DINUCLEOTIDE (FAD) (used as cofactors in redox reactions, as electron carrier)

Vitamin B2 (Riboflavin)

Vitamin B2 deficiency

No deficiency state but with signs and symptoms - stomatitis (inflammation of oral mucosa) - cheilosis (inflammation of lips and angle of mouth) - dermatitis - corneal vascularization

Active forms: NICOTINAMIDE ADENINE DINUCLEOTIDE phosphate (NAD+ and NADP+) (Used as coenzyme in redox reactions, as ➡️ electron carrier; may be derived from tryptophan using Vitamin B6)

Vitamin B3 (Niacin)

Vitamin B3 deficiency

Pellagra = 3Ds (diarrhea, dermatitis, dementia) - Hartnup Disease absorption (⬇️ tryptophan) - Carcinoid Syndrome metabolism (⬆️ tryptophan) - Isoniazid use (⬇️ vitamin B6=⬇️ vitamin B3)

Active form: constituent of Coenzyme A (fatty acid) | used as cofactor for acyl transfers; component of fatty acid synthase

Vitamin B5 (Pantothenate)

Vitamin B5 deficiency

No deficiency state but with signs and symptoms: - dermatitis - enteritis - alopecia - adrenal insufficiency

Active form: PYRIDOXAL PHOSPHATE - Used as coenzyme in AA transamination - used as coenzyme for: glycogen phosphorylase (glycogenolysis), cystathionine synthase, ALA synthase, synthesis of niacin from tryptophan

Vitamin B6 (Pyridoxine)

Vitamin B6 deficiency

Isoniazid toxicity - INH + pyridoxal phosphate = inactive derivative - peripheral neuropathy

Vitamin B6 toxicity

Intake of >2g/day Gait problems and CNS toxicity

Structure: cobalt in center of corrin ring - Methylcobalamin ➡️ contains methyl group - Cyanocobalamin ➡️ contains CN Needs intrinsic factor for absorption - IF produced by stomach parietal cels - absorbed in terminal ileum Active forms: - 5-DEOXYADENOSYLCOBALAMIN: used for methionine synthesis (homocysteine+N-methyl THG -> methionine+THF - Methylcobalamin: used for isomerization reactions (methylmalonyl CoA -> succinyl CoA {methylmalonyl mutase}

Vitamin B12 (Cobalamin)

Vitamin B12 deficiency

Pernicious Anemia - autoimmune destruction of parietal cells leading to ⬇️ IF secretion and ⬇️ vitamin B12 absorption - early SSX: Megaloblastic anemia - late SSX: neuropsychiatric Dx: Schilling Test, Vitamin B12 and anti-IF Other causes: malabsorption or absence of terminal ileum

Structure: PTERIN RING + PARA-AMINOBENZOIC ACID (PABA) + GLUTAMATE RESIDUES - humans cannot synthesize PABA and add glutamate, therefore humans cannot synthesize folate - should be provided from diet Active form: TETRAHYDROFOLATE (THF) PABA ➡️ dihydrofolate (DHF) ➡️ tetrahydrofolate (THF) dihydropteroate synthetase dihydrofolate reductase - used as coenzyme for 1-carbon transfer - Methylation reactions, like synthesis of purines and thymine

Folic acid

Folic acid deficiency

Megaloblastic anemia with no neurological symptoms - hypersegmentation of neutrophils (earliest manifestation) - macrocytic anemia Neural tube defects - pregnant mothers must be given 400mcg (x10) folate daily

Used a cofactor for carboxylation reactions: pyruvate carboxylase (pyruvate➡️oxaloacetate) Acetyl CoA carboxylase (acetyl CoA➡️malonyl CoA) Propionyl CoA carboxylase (propionyl CoA➡️methylmalonyl CoA)

Biotin

Biotin deficiency

Induced by avidin in egg whites Dermatitis Enteritis

Used as a cofactor in: - Hydroxylation of proline and lysine (collagen synthesis) - Dopamine B-hydroxylase (dopamine to norepinephrine) Reduces Fe3 to Fe2 in stomach to ⬆️Fe absorption (Ferric ➡️ Ferrous)

Vitamin C (Ascorbic Acid)

Vitamin C deficiency

Scurvy - loose teeth and sore guns - swollen joints - fragile vessels - anemia