Vitamins

Question 1

Vitamin A function

Answer 1

Antioxidant
Part of visual pigment retinal
Differentiation of epithelial cells (pancreatic cc or mucus-secreting cc)
Prevents squamous metaplasia
Treat measles and acute promyelocytic leukemia

Topical tx for wrinkles and acne
Found in liver and leafy veggies
PO isotretinoin for severe cystic acne
ATRA for APML

Question 2

Vitamin A deficiency

Answer 2

Night blindness (nyctalopia); dry, scaly skin (xerosis cutis), corneal degeneration (keratomalacia), bitot spots on conjunctiva, immunosuppression

Question 3

Vitamin A toxicity

Answer 3

Acute: nausea/vomiting, vertigo, blurred vision

Chronic: alopecia, dry skin, hepatotoxicity and enlargement, arthralgias, pseudotumor cerebri

Teratogen: cleft palate/ cardiac abnormalities; required pregnancy test before isotretinoin Rx

Question 4

Vitamin B1 (thiamine) function

Answer 4

A part of thiamine pyrophosphate (TPP), a cofactor for:
Pyruvate dehydrogenase (links glycolysis to TCA cycle)
alpha-ketoglutarate dehydrogenase (TCA cycle)
Transketolase (HMP shunt)
Branch-chain ketoacid dehydrogenase

Question 5

Vitamin B1 (thiamine) deficiency

Answer 5

Impaired glucose breakdown, low ATP worsened by glucose infusion, aerobic tissue affected first

In alcoholic patients gives thiamine before dextrose to stop precipitating Wernicke’s encephalophathy

Dg: increased transketolase activity in RBCs post B1 administration

Question 6

Vitamin B1 (thiamine) diseases

Answer 6

Wernicke-Korsakoff syndrome: confusion, ophthalmoplegia, ataxia with confabulation, personality changes, damage to medial dorsal nucleus of thalamus, mammillary bodies

Dry beriberi- polyneuritis and symmetrical muscle wasting

Wet beriberi- HFpEF (DCM), edema

Question 7

Vitamin B2 (riboflavin) function

Answer 7

Part of flavins (FAD and FMN) cofactors in redox reactions (eg succinate dehydrogenase in TCA cycle)

Question 8

Vitamin B2 (riboflavin) deficiency

Answer 8

Cheilosis (inflammation of lips, scaling and fissures at corners of mouth), corneal vascularization

Question 9

Vitamin B3 (niacin) function

Answer 9

Part of NAD+, NADP+ (redox), derived from tryptophan and synthesis requires B2 and B6

Treats dyslipidemia: lowers VLDL and raises HDL

Question 10

Vitamin B3 (niacin) deficiency

Answer 10

Glossitis
Severe leads to pellagra (can also be caused by Hartnup disease, malignant carcinoid sy (increased tryptophan metabolism) and isoniazid (decreased B6))
Pellagra: diarrhea, dementia, dermatitis (dermatomal), hyperpigmentation of exposed skin

Question 11

Vitamin B3 (niacin) deficiency- Hartnup disease

Answer 11

AR deficiency of neutral amino acid transporters in PCT and on enterocytes (neutral aminoaciduria) so less tryptophan for conversion to niacin
Tx: high protein diet, and nicotinic acid

Question 12

Vitamin B3 (niacin) excess

Answer 12

Facial flushing (PGs) avoid by taking ASA with niacin, hyperglycemia, hyperuricemia

Question 13

Vitamin B5 (pantothenic acid) function

Answer 13

Essential for CoA (acyl transfers) and fatty acid synthase

Question 14

Vitamin B5 (pantothenic acid) deficiency

Answer 14

Dermatitis, enteritis, alopecia, adrenal insuff.

Question 15

Vitamin B6 (pyridoxine) function

Answer 15

Converted to pyridoxal phosphate (PLP) cofactor in transamination (ALT and AST), decarboxylaton, glycogen phosphorylase
Needed to make: cystathionine, heme, niacin, histamine, NTs (serotonin, epi, norepi, DA and GABA)

Question 16

Vitamin B6 (pyridoxine) deficiency

Answer 16

Convulsions, irritability, peripheral neuropathy (inducible by iNH and OCPs), sideroblasitic anemia due to impaired Hgb synth and iron excess

Question 17

Vitamin B7 (biotin) function

Answer 17

Cofactor for carboxylation (add 1C)
Pyruvate carboxylase (pyruvate to oxaloacetate)
AcetylCoA carboxylase (acetylCoA to malonyl CoA)
PropionylCoA carboxylase (PropionylCoA to methylmalonylCoA)

Avidin in eggwhites can bind biotin and cause deficiency

Question 18

Vitamin B7 (biotin) deficiency

Answer 18

Dermatitis, alopecia, enteritis

Caused by Abx or eggwhites

Question 19

Vitamin B9 (folate) function

Answer 19

Converted to THF (coenzyme for 1-carbon transfer/methylation reactions)
Synthesis of nitrogenous vases for DNA and RNA
Found in leafy green veggies, absorbed in jejunum, stored in liver

Question 20

Vitamin B9 (folate) deficiency

Answer 20

Macrocytic megaloblastic anemia; hypersegmented PMNs, glossitis, NO NEURO

Labs: elevated homocysteine, nl methylmalonic acid
Assoc with alcoholism in pregnancy

Drugs can cause: phenytoin, sulfonamides, methotrexate
Supplement at least 1 mo prior to conception and during preg to prevent neural tube defects

Question 21

Vitamin B12 (cobalamin) function

Answer 21

Cofactor for methionine synthase (transfers methyl group as methycobalamin) AND methylmalonyl-CoA mutase. Important in DNA synthesis.

Found in animal products, reserve for years in liver

Question 22

Vitamin B12 (cobalamin) deficiency

Answer 22

Macrocytic megaloblastic anemia; hypersegmented PMNs, glossitis, paresthesias, subacute combined degeneration (dorsal columns, lateral corticospinal tracts and spinocerebellar tracts) due to abnl myelin; can lead to irrev. nerve damage

Causes: malabsorption (ileum) from sprue, enteritis, tape worm, lack of IF (bypass, pernicious anemia), lack of ileum (surgery, CD), veganism

Labs: elevated homocysteine, methylmalonic acid and 2˚ folate deficiency

Question 23

Vitamin C (ascorbic acid) function

Answer 23

Antioxidant; facilitates Fe absorption by reducing to Fe2+; necessary for hydroxylation of pro and lys residues in preprocollagen; necessary for dopamine-beta-hydroxylase which converts DA to NE

Found in fruits and veggies

Ancillary tx for methemoglobinemia for reducing Fe to Fe2+

Question 24

Vitamin C (ascorbic acid) deficiency

Answer 24

Scurvy- swollen gums, bruising, petechiae, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages, corckscrew hair
Weakened immune response

Question 25

Vitamin C (ascorbic acid) excess

Answer 25

Nausea, vomiting, diarrhea, fatigue, Ca oxalate stones, increased risk of iron tox. in transfused or ppl with hemochromatosis

Question 26

Vitamin D forms

Answer 26

D2- ergocalciferol- ingested from plants D3- cholecalciferol- consumed in milk, formed in sun exposed stratum basale 25-OH D3 - storage form 1,25-(OH)2D3 - calcitriol (active form)

Question 27

Vitamin D function

Answer 27

Intestinal absorption of Ca and phosphate, increased bone mineralization at low levels, bone resorption at high levels

Question 28

Vitamin D deficiency

Answer 28

Rickets in kids (varum bow legs); osteomalacia in adults (bone pain and muscle weakness), hypocalcemic tetany; breastfed infants need oral vit D. Deficiency is exacerbated by sun exposure, pigmented skin, prematurity

Question 29

Vitamin D excess

Answer 29

Hypercalcemia, hypercalciuria, loss of appetite, stupor | Seen in granulomatous disease (increased D activation by epithelioid histocytes)

Question 30

Vitamin E (tocopherol/tocotrienol) function

Answer 30

Antioxidant- protects RBC and membranes from free radical damage HD supplementation may alter vitamin K metabolism to enhance warfarin anticoagulation

Question 31

Vitamin E (tocopherol/tocotrienol) deficiency

Answer 31

Hemolytic anemia, acanthoytosis, muscle weakness, posterior column and spinocerebellar tract demyelination May look like B12 deficiency; without megaloblastic anemia or hypersegmented neutrophils or methylmalonic acid

Question 32

Vitamin K (phytomenadione, phylloquinone, phytonadione) function

Answer 32

Activated by epoxide reductase to reduced form which is a cofactor for gamma-carboxylation of glutamic acid residues on factors II, VII, IX and X + proteins C and S Found in plants Warfarin inhibits K-dep synth of above factors

Question 33

Vitamin K (phytomenadione, phylloquinone, phytonadione) deficiency

Answer 33

Neonatal hemorrhage with elevated PT and aPTT; nl bleeding time, because can't synth K due to sterile intestines; also post-prolonged Abx Not in breast milk, give vit. K injection at birth

Question 34

Zinc function

Answer 34

essential for many enzymes especially transcription factors

Question 35

Zink deficiency

Answer 35

Delayed would healing, hypogonadism, lose of adult hair, dysgeusia, anosmia, acrodermatits enteropathica; predispose to alcoholic cirrhosis