FIRST AID USMLE STEP 1 - VITAMINSQUESTIONS WITH 100% SOLVED SOLUTIONS!!

Vitamin B1 (thiamine) - Deficiency - Impaired glucose breakdown p ATP depletion worsened by glucose infusion; highly aerobic tissues (eg, brain, heart) are affected first. In alcoholic or malnourished patients, give thiamine before dextrose to reduce risk of precipitating Wernicke encephalopathy. Diagnosis made by increase in RBC transketolase activity following vitamin B1 administration Vitamin A (retinol) - Excess - Acute toxicity—nausea, vomiting, vertigo, and blurred vision. Chronic toxicity—alopecia, dry skin (eg, scaliness), hepatic toxicity and enlargement, arthralgias, and pseudotumor cerebri. Teratogenic (cleft palate, cardiac abnormalities), therefore a ⊝ pregnancy test and two forms of contraception are required before isotretinoin (vitamin A derivative) is prescribed. Vitamin A (retinol) - Function - Antioxidant; constituent of visual pigments (retinal); essential for normal differentiation of epithelial cells into specialized tissue (pancreatic cells, mucus-secreting cells); prevents squamous metaplasia. Used to treat measles and acute promyelocytic leukemia (APL). . Vitamin B1 (thiamine) - Extra - Think ATP: α-ketoglutarate dehydrogenase, Transketolase, and Pyruvate dehydrogenase. Spell beriberi as Ber1Ber1 to remember vitamin B1. Wernicke-Korsakoff syndrome —confusion, ophthalmoplegia, ataxia (classic triad) + confabulation, personality change, memory loss (permanent). Damage to medial dorsal nucleus of thalamus, mammillary bodies. Dry beriberi —polyneuritis, symmetrical muscle wasting. Wet beriberi —high-output cardiac failure (dilated cardiomyopathy), edema. Vitamin B1 (thiamine) - Function - In thiamine pyrophosphate (TPP), a cofactor for several dehydrogenase enzyme reactions: +Pyruvate dehydrogenase (links glycolysis to TCA cycle) +α- ketoglutarate dehydrogenase (TCA cycle) +Transketolase (HMP shunt) +Branched-chain ketoacid dehydrogenase Vitamin B12 (cobalamin) - Deficiency - Macrocytic, megaloblastic anemia; hypersegmented PMNs; paresthesias and subacute combined degeneration (degeneration of dorsal columns, lateral corticospinal tracts, and spinocerebellar tracts) due to abnormal myelin. Associated with increased serum homocysteine and methylmalonic acid levels, along with 2° folate deficiency. Prolonged deficiency -> irreversible nerve damage.Vitamin B12 (cobalamin) - Extra - Found in animal products. Synthesized only by microorganisms. Very large reserve pool (several years) stored primarily in the liver. Deficiency caused by malabsorption (eg, sprue, enteritis, Diphyllobothrium latum ), lack of intrinsic factor (pernicious anemia, gastric bypass surgery), absence of terminal ileum (surgical resection, eg, for Crohn disease), or insufficient intake (eg, veganism). Anti-intrinsic factor antibodies diagnostic for pernicious anemia. Vitamin A (retinol) - Deficiency - Night blindness (nyctalopia); dry, scaly skin (xerosis cutis); corneal degeneration (keratomalacia); Bitot spots on conjunctiva; immunosuppression. Vitamin B12 (cobalamin) - Function - Cofactor for methionine synthase (transfers CH3 groups as methylcobalamin) and methylmalonyl-CoA mutase. Important for DNA synthesis. Vitamin B2 (riboflavin) - Deficiency - Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), Corneal vascularization. Vitamin B2 (riboflavin) - Extra - FAD and FMN are derived from riboFlavin (B2 ≈ 2 ATP). The 2 C's of B2 . Vitamin B2 (riboflavin) - Function - Component of flavins FAD and FMN, used as cofactors in redox reactions, eg, the succinate dehydrogenase reaction in the TCA cycle. Vitamin B3 (niacin) - Deficiency - Glossitis. Severe deficiency leads to pellagra, which can be caused by Hartnup disease, malignant carcinoid syndrome ( increased tryptophan metabolism), and isoniazid ( decreased vitamin B6). Symptoms of pellagra: Diarrhea, Dementia (also hallucinations) , Dermatitis (C3/C4 dermatome circumferential "broad collar" rash [Casal necklace], hyperpigmentation of sun- exposed limbs A ). Vitamin B3 (niacin) - Excess - Facial flushing (induced by prostaglandin, not histamine; can avoid by taking aspirin with niacin), hyperglycemia, hyperuricemia. Vitamin B3 (niacin) - Extra - NAD derived from Niacin (B3 ≈ 3 ATP). The 3 D's of B3 . Hartnup disease —autosomal recessive. Deficiency of neutral amino acid (eg, tryptophan) transporters in proximal renal tubular cells and on enterocytes -> neutral aminoaciduria and decreased absorption from the gut -> increased tryptophan for conversion to niacin -> pellagra-like symptoms. Treat with highprotein diet and nicotinic acidVitamin B3 (niacin) - Function - Constituent of NAD+, NADP+ (used in redox reactions). Derived from tryptophan. Synthesis requires vitamins B2 and B6 . Used to treat dyslipidemia; lowers levels of VLDL and raises levels of HDL. Vitamin B5 (pantothenic acid) - Deficiency - Dermatitis, enteritis, alopecia, adrenal insufficiency. Vitamin B5 (pantothenic acid) - Extra - B5 is " pento" thenic acid. Vitamin B5 (pantothenic acid) - Function - Essential component of coenzyme A (CoA, a cofactor for acyl transfers) and fatty acid synthase. Vitamin B6 (pyridoxine) - Deficiency - Convulsions, hyperirritability, peripheral neuropathy (deficiency inducible by isoniazid and oral contraceptives), sideroblastic anemias due to impaired hemoglobin synthesis and iron excess. Vitamin B6 (pyridoxine) - Function - Converted to pyridoxal phosphate (PLP), a cofactor used in transamination (eg, ALT and AST), decarboxylation reactions, glycogen phosphorylase. Synthesis of cystathionine, heme, niacin, histamine, and neurotransmitters including serotonin, epinephrine, norepinephrine (NE), dopamine, and GABA. Vitamin B7 (biotin) - Deficiency - Relatively rare. Dermatitis, alopecia, enteritis. Caused by antibiotic use or excessive ingestion of raw egg whites. Vitamin B7 (biotin) - Extra - "Avidin in egg whites avidly binds biotin." Vitamin B7 (biotin) - Function - Cofactor for carboxylation enzymes (which add a 1-carbon group): +Pyruvate carboxylase: pyruvate (3C) -> oxaloacetate (4C) +Acetyl-CoA carboxylase: acetyl-CoA (2C) -> malonyl-CoA (3C) +Propionyl-CoA carboxylase: propionyl-CoA (3C) -> methylmalonyl-CoA (4C) Vitamin B9 (folate) - Deficiency - Macrocytic, megaloblastic anemia; hypersegmented polymorphonuclear cells (PMNs); glossitis; no neurologic symptoms (as opposed to vitamin B12 deficiency). Labs: increased homocysteine, normal methylmalonic acid levels. Most common vitamin deficiency in the United States. Seen in alcoholism and pregnancy.Vitamin B9 (folate) - Extra - Found in leafy green vegetables. Absorbed in jejunum. Fol ate from foliage. Small reserve pool stored primarily in the liver. Deficiency can be caused by several drugs (eg, phenytoin, sulfonamides, methotrexate). Supplemental maternal folic acid at least 1 month prior to conception and during early pregnancy to decrease risk of neural tube defects. Vitamin B9 (folate) - Function - Converted to tetrahydrofolic acid (THF), a coenzyme for 1-carbon transfer/methylation reactions. Important for the synthesis of nitrogenous bases in DNA and RNA. Vitamin C (ascorbic acid) - Deficiency - Scurvy —swollen gums, bruising, petechiae, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages, "corkscrew" hair. Weakened immune response. Vitamin A (retinol) - Extra - Retinol is vitamin A, so think retin-A (used topically for wrinkles and Acne). Found in liver and leafy vegetables. Use oral isotretinoin to treat severe cystic acne. Use all-trans retinoic acid to treat acute promyelocytic leukemia. Isotretinoin is teratogenic