Deck 29: Vitamins and Minerals

Question 1

Free radicals are molecular terrorists that attack molecular targets indiscriminately.Their formation in the body cannot be prevented, because they are unavoidable byproducts of oxidative metabolism, but physicians can try to intercept them before they hit a sensitive target-for example, by an extra good supply of:

A)Niacin.
B)Thiamin.
C)Pyridoxine.
D)Vitamin D.
E)Vitamin E.

Answer 1

Vitamin E.

Question 2

You look over the laboratory reports of 500 medical students to determine the frequency of iron deficiency in this population.The best way to identify iron deficiency from laboratory reports would be to define as iron-deficient all those with:

A)A hematocrit below 50%.
B)A reduced level of serum transferrin.
C)An elevated level of serum ferritin.
D)A transferrin saturation of less than 15%.
E)An iron concentration of less than 5 mg/liter in the urine.

Answer 2

A transferrin saturation of less than 15%.

Question 3

Sunlight is good for your bones because:

A)It induces the 25-hydroxylase in the kidneys that makes active calcitriol.
B)It converts 7-dehydrocholesterol to cholecalciferol in the skin.
C)It induces the synthesis of retinol-binding protein in the skin.
D)It carboxylates vitamin K in the skin.
E)It converts tryptophan to niacin in the skin.

Answer 3

It converts 7-dehydrocholesterol to cholecalciferol in the skin.

Question 4

Vitamin deficiencies are rarely seen in newborns.However, one vitamin that should be given shortly after birth to prevent any risk of deficiency is:

A)Vitamin A.
B)Niacin.
C)Riboflavin.
D)Vitamin K.
E)Biotin.

Question 5

A medical student is brought to the student health center in a confused state.His friends report that he is a heavy drinker and that he subsisted mainly on cola fortified with gin during the past 2 years.However, he does not seem acutely drunk when seen by the doctor.It would be prudent to give this student immediately a high dose of:

A)Iron.
B)Thiamin.
C)Alcohol.
D)Vitamin A.
E)Biotin.

Question 6

After developing mild jaundice, a teenage boy is found to have an alanine transaminase level eight times higher than the upper limit of normal.A low level of serum ceruloplasmin is subsequently found.There is no fever.This boy most likely has:

A)Hemochromatosis.
B)Menke disease.
C)Wilson disease.
D)Lung emphysema.
E)Acute biliary obstruction.

Question 7

The iron overload disease hemochromatosis is caused by a mutation in the HFE gene that originated only recently and that is now most common in:

A)Northern Europe.
B)The Indian subcontinent.
C)Tropical Africa.
D)The Mediterranean countries.
E)East Asia.

Question 8

Patients in renal failure require dietary restriction of all the following nutrients except:

A)Calcium.
B)Phosphate.
C)Sodium.
D)Protein.
E)Potassium.

Question 9

A woman in her early 30s is found to be a hemochromatosis homozygote, but her serum ferritin level and transferrin saturation are only slightly increased.Which of the following is most likely to further increase her serum iron?

A)A strict vegetarian diet.
B)Menstruation limited to once a year.
C)Avoidance of alcohol.
D)Increased physical exercise.
E)A diet that is low in vitamin C.

Question 10

Acute severe fat malabsorption can cause deficiencies of fat-soluble vitamins.The fat-soluble vitamin that becomes deficient first, after only 1 or 2 weeks of fat malabsorption, is:

A)Vitamin E.
B)Vitamin K.
C)Vitamin A.
D)Vitamin D.
E)None of the fat-soluble vitamins becomes deficient within the first 6 months of fat malabsorption.

Question 11

On your arrival in a refugee camp in a nation undergoing civil war, you notice that many people in the camp have severe skin lesions on parts of the body that are exposed to the sun.The residents of the camp have to subsist on maize and cassava, everything else having been confiscated by the military.The vitamin deficiency that is the most likely cause of these skin lesions is:

A)Thiamin.
B)Niacin.
C)Biotin.
D)Folic acid.
E)Vitamin E.

Question 12

Niacin deficiency causes pellagra.This disease is seen only in patients with a diet that is low in both niacin and:

A)Choline.
B)Creatine.
C)Thiamin.
D)Methionine.
E)Tryptophan.

Question 13

What is true about scurvy?

A)It can occur not only in humans but also in most other animals, such as dogs and cats.
B)Some signs of scurvy can be treated with artificial vitamin C, but some signs can be treated only with vitamin C from natural sources.
C)Gooseflesh and easy bruising are typical signs.
D)Treatment with at least 1 g of vitamin C per day is needed to relieve the clinical signs and symptoms of scurvy.
E)The mechanism for most of the symptoms of scurvy is the inability to remove the propeptides during the processing of procollagen to collagen.

Question 14

Cholecalciferol, formed by the action of sunlight on 7-dehydrocholesterol in the skin, has to be converted to the fully active calcitriol before it can induce its physiological actions.The rate-limiting step in this process is catalyzed by an enzyme in:

A)The lungs.
B)The liver.
C)The brain.
D)The kidneys.
E)The intestines.

Question 15

A 28-year-old man who saw the doctor because of numbness of the feet is found to have a hematocrit of 26%.Except for frequent bouts of gastritis for which he self-medicated with antacids, there is nothing unusual in his medical history.A blood test shows unusually large erythrocytes, and a metabolic screen reveals methylmalonic acid in his urine.This is most likely a case of:

A)Folate deficiency.
B)ẞ-Thalassemia.
C)Iron deficiency.
D)Deficiency of vitamin B6.
E)Pernicious anemia.

Question 16

Retinoic acid is a form of vitamin A that is most important as a:

A)Gene regulator.
B)Cofactor for hydroxylation reactions.
C)Constituent of the respiratory chain.
D)Cofactor for oxidative decarboxylation reactions.
E)Coenzyme in many reactions of amino acid metabolism.