KJZ Vitamin Functions & Deficiencies
About this set
kzachari on May 20, 2011
Table 2.17-7 from First Aid for the USMLE Step 2 CK plus extra information on function
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|Vitamin A fxn||Antioxidant constituent of visual pigments; needed for specialized tissue cell differentiation (pancreatic, mucus-secreting).|
|Vitamin A def||Night blindness, dry skin.|
|Vitamin B1 (thiamine) fxn||Cofactor for pyruvate dehydrogenase (glycolysis), alpha-ketoglutarate dehydrogenase (TCA), transketolase (HMP), and branched chain AA dehydrogenase|
|Vitamin B1 def|| Impaired glucose breakdown leads to ATP depletion especially in highly aerobic tissues (brain, heart); causes:|
- Wernicke-Korsakoff syndrome (confusion, opthalmoplegia, focal hemorrhage in mamillary bodies),
- beri-beri (dry-polyneuritis, muscle wasting; wet-dilated cardiomyopathy, edema).
|Vitamin B2 (riboflavin) fxn||Cofactor in oxidation and reduction.|
|Vitamin B2 def||Cheilosis (inflammation of lips with scalin and fissures at corners of mouth), corneal vascularization, angluar stomatitis.|
|Vitamin B3 (niacin) fxn||Constituent of NAD+, NADP+; derived from tryptophan; synthesis requires B6.|
|Vitamin B3 def|| Glossitis, pellagra (diarrhea, dermatitis, dementia); |
can be caused by INH (decreased B6) or malignant carcinoid syndrome (increased tryptophan metabolism).
|Vitamine B5 (pantothenate) fxn||Component of CoA and fatty acid synthesis.|
|Vitamin B5 def||Dermatitis, enteritis, alopecia, adrenal insufficiency.|
|Vitamin B6 (pyridoxine) fxn||Converted to pyridoxal phosphate, cofactor in transamination, decarboxylation, glycogen phosphorylase, cystathionine and heme synthesis; required for niacin synthesis|
|Vitamin B6 def||Convulsions, hyperirritability, peripheral neuropathy, sideroblastic anemia, required during admin of INH.|
|Vitamin B12 (cobalamin) fxn||Cofactor for homocysteine methyltransferase|
|Vitamin B12 def||Macrocytic megaloblastic anemia, hypersegmented PMNs, neurologic sx (paresthesias, subacute combined degeneration, optic neuropathy), glossitis, increased levels of homocysteine and methylmalonic acid.|
|Vitamin C fxn||Antioxidant; facilitates iron absorption; necessary for proline and lysine hydroxylation in collagen synthesis; necessary for dopamine beta-hydroxylase.|
|Vitamin C def||Scurvy: swollen gums, anemia, poor wound healing.|
|Vitamin D fxn||Increases intestinal absorption of calcium and phosphate; increases bone resorption.|
|Vitamin D def|| Rickets in children (bending bone); |
Osteomalacia (soft bone) and hypocalcemic tetany in adults.
|Vitamin E fxn||Antioxidant protects erythrocytes and membranes from free-radical damage.|
|Vitamin E def||Increased erythrocyte fragility leads to hemolytic anemia, muscle weakness, neurodysfunction.|
|Vitamin K fxn||Catalyzes gamma-carboxylation of glutamic acid residues on blood clotting proteins.|
|Vitamin K def||Neonatal hemorrhage with normal bleeding time, increased PT and PTT.|
|Biotin fxn||Cofactor for carboxylation enzymes.|
|Biotin def|| Dermatitis, alopecia, enteritis; |
caused by antibiotic use or excessive RAW EGG ingestion.
|Folic acid fxn||Converted to THF, coenzyme for 1-carbon transfer (methylation) reactions.|
|Folic acid def|| THE MC VIT DEFICIENCY IN THE US;|
Sprue, macrocytic megaloblastic anemia, no neurologic symptoms; increased homocysteine, normal methylmalonic acid
|Magnesium def||Weakness, nuscle cramps, exacerbation of hypocalcemic tetany, CNS hyperirritability leading to tremors, choreathetoid movement.|
|Selenum def||Keshan disease (cardiomyopathy).|
|Zinc fxn||Essential for activity of 100+ enzymes; needed for zinc finger transcription factor motif.|
|Zinc def||Delayed wound healing, hypogonadism, decreased adult hair, dysgeusia, anosmia.|