Biochem - Nutrition/Vitamins Flashcards
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
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)
Dermatitis, enteritis, alopecia, adrenal insufficiency.
B5 is “pento”thenate
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.
Marasmus
energy malnutrition, muscle wasting
outcomes of Vitamin A deficiency 5
- Night blindness (nyctalopia)
- dry, scaly skin (xerosis cutis)
- alopecia
- corneal degeneration (keratomalacia)
- immune suppression.
polyneuritis, symmetrical muscle wasting.
Dry Beriberi, Thiamine deficiency
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!
a cofactor used in transamination (e.g., ALT and AST), decarboxylation reactions, glycogen phosphorylase.
B6 (pyridoxine)
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)
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
vitamin E
function
how deficiency presents
fat-soluble
function: antioxidant for erythrocytes
deficiency: hemolytic anemia, neuropathy
wet beriberi
high-output cardiac failure due to thiamine deficiency
thiamine - which vitamin?
B1
Vitamin B1 deficiency
Wernicke-Korsakoff syndrome and beriberi (Ber1Ber1)
treatment of cobalamin deficiency with folic acid results in
subacute combined degeneration of dorsal columns.
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.
Folate - which vitamin?
B9
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
zinc
function?
deficiency?
function: widespread, transcription factors
deficiency: metallic taste, delayed wound healing, hypogonadism, acrodermatitis enteropathica
Niacin is used to treat:
dyslipidemia; lowers levels of VLDL and raises levels of HDL.
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
Vitamin A excess - 6
- Teratogen
- Skin ∆s (scaliness)
- alopecia
- cerebral edema “pseudotumor cerebri”
- osteoporosis
- hepatic abnormalities
Diarrhea
Dementia (also hallucinations)
Dermatitis (casal necklace or hyperpigmentation of sun-exposed limbs)
Pellagra (vitamin B3 deficiency” The 3 D’s of B3
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
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)
biotin - which vitamin?
B7
Folic acid deficiency can be caused by these Rx
phenytoin, sulfonamides, methotrexate
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
3 causes of vitamin K deficiency:
- warfarin
- neonates (sterile intestines - remember Vit K is made by intestinal flora)
- Antibiotic use (kills off intestinal flora)
Total calorie malnutrition resulting in tissue and muscle wasting, loss of subcutaneous fat, and variable edema.
Marasmus = Muscle wasting.
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
folic acid is initially converted into:
THF (a coenzyme required to convert homocysteine into methionine)
vitamin B2 (riboflavin)
function
how deficiency presents
function: cofactor for FADH2 (oxidation and reduction)
deficiency: cheilosis, corneal vascularization
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).
Essential component of coenzyme A and fatty acid synthase.
Vitamin B5 (pantothenate)
Hemolytic anemia, acanthocytosis, muscle weakness, posterior column and spinocerebellar tract demyelination.
Vitamin E deficiency (tocopherol/tocotrienol)
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
niacin - which vitamin?
B3
labs of cobalamin deficiency
incr. serum homocysteine AND methylmalonic acid levels.
drug for alcoholics to take to decrease intake
Disulfiram - inhibits acetaldehyde dehydrogenase (acetaldehyde accumulates, contributing to instant hangover symptoms)
high-output cardiac failure (dilated cardiomyopathy), edema.
Wet beriberi due to thiamine B1 deficiency
pantothenic acid - which vitamin?
B5
eating too much raw eggs will cause deficiency in this
B7 deficiency “Avidin in egg whites avidly binds biotin.”
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
dry beriberi
polyneuritis and muscle wasting
due to thiamine deficiency
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).
ascorbic acid - which vitamin?
Vitamin C
one malignancy that causes increase vitamin D?
Sarcoidosis (incr. activation of vitamin D by epithelioid macrophages).
retinol - which vitamin?
Vitamin A
B2 forms these two factors:
FAD and FMN are derived from riboFlavin (B2 = 2 ATP).
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
Delayed wound healing
hypogonadism
decreased adult hair (axillary, facial, pubic)
dysgeusia
anosmia
acrodermatitis enteropathica
zinc deficiency
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)
Excess niacin cause these 3 sx
- Facial flushing (induced by prostaglandins, not histamine)
- hyperglycemia
- hyperuricemia
Folic acid deficiency can cause these labs
incr. homocysteine
normal methylmalonic acid
Vitamin A can be used to treat these 2 diseases
measles AML, subtype 3
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)
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
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
small child with swollen belly
Kwashiorkor - Protein malnutrition resulting in skin lesions, edema, liver malfunction (fatty change due to decreased apolipoprotein synthesis).
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
Vitamin E function?
Antioxidant (protects erythrocytes and membranes from free radical damage).
E is for Erythrocytes.Can enhance anticoagulant effects of warfarin
Patient with cheilosis & corneal vascularization
B2 deficiency (riboflavin)
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.
vitamin C (ascorbic acid)
function
how deficiency presents
how excess presents
- function: antioxidant, collagen synthesis, NE synthesis
- deficiency: scurvy
- excess: GI symptoms, iron toxicity
this supplementation decreases risk of neural tube defects
folic acid
Sx of vitamin D excess?
Hypercalcemia, hypercalciuria, loss of appetite, stupor
vitamin B5 (pantothenate)
function?
deficiency?
function: part of CoA and fatty acid synthase
deficiency: dermatitis, alopecia, adrenal insufficiency
How to diagnose B1 deficiency?
measure increase in RBC transketolase activity following vitamin B1/thiamine administration.
5 symptoms of B6 deficiency
- Convulsions
- Hyperirritability
- Peripheral neuropathy
- Sideroblastic anemias (impaired hemoglobin synthesis and iron excess)
- according to Uworld: also seborrheic dermatitis, glossitis
cobalmin - which vitamin?
B12
riboflavin - which vitamin?
B2
If you see these dermatitis, alopecia, enteritis, you should think of:
B-complex deficiencies (B5, B7)
antidoate for methanol and ethylene glycol poisoning
fomepizole - inhibits alcohol dehydrogenase
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
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.
all vitamins wash out from the body except for these two:
B12 and folate (stored in liver).
pyridoxine - which vitamin?
B6
Kwashiorkor presentation and cause
small child with swollen belly
protein malnutrition, edema, anemia, fatty liver
how a patient with Wernicke-Korsakoff presents
- ataxia, memory loss, confabulation, opthalmoplegia, confusion
- damaged mamillary bodies
