©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
FIRST AID USMLE STEP 1 – VITAMINS
EXAM STUDY GUIDE SOLUTIONS
Vitamin A (retinol) - Function - ANSWER✔✔-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 A (retinol) - Deficiency - ANSWER✔✔-Night blindness (nyctalopia); dry, scaly skin (xerosis cutis);
corneal degeneration (keratomalacia); Bitot spots on conjunctiva; immunosuppression.
Vitamin A (retinol) - Excess - ANSWER✔✔-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) - Extra - ANSWER✔✔-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.
Page 1/8
, ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
Vitamin B1 (thiamine) - Function - ANSWER✔✔-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 B1 (thiamine) - Deficiency - ANSWER✔✔-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 B1 (thiamine) - Extra - ANSWER✔✔-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 B2 (riboflavin) - Function - ANSWER✔✔-Component of flavins FAD and FMN, used as cofactors in
redox reactions, eg, the succinate dehydrogenase reaction in the TCA cycle.
Vitamin B2 (riboflavin) - Deficiency - ANSWER✔✔-Cheilosis (inflammation of lips, scaling and fissures at
the corners of the mouth), Corneal vascularization.
Page 2/8
FIRST PUBLISH OCTOBER 2024
FIRST AID USMLE STEP 1 – VITAMINS
EXAM STUDY GUIDE SOLUTIONS
Vitamin A (retinol) - Function - ANSWER✔✔-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 A (retinol) - Deficiency - ANSWER✔✔-Night blindness (nyctalopia); dry, scaly skin (xerosis cutis);
corneal degeneration (keratomalacia); Bitot spots on conjunctiva; immunosuppression.
Vitamin A (retinol) - Excess - ANSWER✔✔-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) - Extra - ANSWER✔✔-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.
Page 1/8
, ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
Vitamin B1 (thiamine) - Function - ANSWER✔✔-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 B1 (thiamine) - Deficiency - ANSWER✔✔-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 B1 (thiamine) - Extra - ANSWER✔✔-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 B2 (riboflavin) - Function - ANSWER✔✔-Component of flavins FAD and FMN, used as cofactors in
redox reactions, eg, the succinate dehydrogenase reaction in the TCA cycle.
Vitamin B2 (riboflavin) - Deficiency - ANSWER✔✔-Cheilosis (inflammation of lips, scaling and fissures at
the corners of the mouth), Corneal vascularization.
Page 2/8
