Clinical Correlates 10 Nutrition

Question 1

___ ___ is characterized by self-induced weight loss. Individuals frequently affected include young, affluent, white women, who despite an emaciated appearance, often claim to be ‘‘fat.’’ It is partially a behavioral problem; those afflicted are obsessed with losing weight.

Answer 1

Anorexia nervosa

Question 2

Essential amino acids

a. ___ amino acids cannot be synthesized in the body and are required in the diet: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
b. Only a small amount of ___ is required in the diet; however, larger amounts are required for growth (e.g., children, pregnant women, people recovering from injuries).
c. ___ can be synthesized in limited amounts and is required in the diet for growth.

Answer 2

Nine
histidine
Arginine

Question 3

___ commonly occurs in children in developing countries where the diet, adequate in calories, is low in protein. A deficiency of dietary protein causes a decrease in protein synthesis and eventually inhibits regeneration of intestinal epithelial cells, further compounded by malabsorption. ___ and a distended abdomen are often observed.

Answer 3

Kwashiorkor

Hepatomegaly

Question 4

___ results from a diet deficient in both protein and calories. Persistent starvation ultimately results in death.

Answer 4

Marasmus

Question 5

water soluble vitamin deficiencies

Thiamine B1

Answer 5

Clinical Consequence of Vitamin Deficiency

Beriberi: high-output heart failure (wet beriberi) and peripheral neuropathy (dry beriberi).

Wernicke-Korsakoff syndrome: deficiency in chronic alcoholics manifesting with ataxia, ophthalmoplegia, confusion, and confabulation

Question 6

water soluble vitamin deficiencies

Riboflavin B2

Answer 6

Clinical Consequence of Vitamin Deficiency

Rare deficiency because grain and cereal products are fortified with riboflavin. Deficiency is associated with atrophy of the tongue (glossitis), fissures of the corner of the mouth (cheilosis), dermatitis, and corneal ulceration.

Question 7

water soluble vitamin deficiencies

Niacin B3

Answer 7

Clinical Consequence of Vitamin Deficiency

Deficiency results in pellagra, characterized by diarrhea, dementia, and dermatitis. Deficiency can result from the antituberculoid medication isoniazid, Hartnup disease, or carcinoid syndrome.

Question 8

water soluble vitamin deficiencies

Pyridoxine B6

Answer 8

Clinical Consequence of Vitamin Deficiency

Most severe symptoms due to the requirement for decarboxylating glutamic acid to the inhibitory neurotransmitter GABA, resulting in seizures. Deficiency can be associated with isoniazid or penicillamine use.

Question 9

water soluble vitamin deficiencies

Biotin

Answer 9

Clinical Consequence of Vitamin Deficiency

Deficiency is rare because biotin is synthesized by gastrointestinal bacteria, although deficiency may be associated with long-term antibiotic use. Deficiency is also associated with the consumption of raw eggs, containing avidin, that binds and inhibits absorption of biotin.

Question 10

water soluble vitamin deficiencies

Cobalamin B12

Answer 10

Clinical Consequence of Vitamin Deficiency

Deficiency associated with lack of intrinsic factor, produced by parietal cells of the stomach. Deficiency results in a block in purine and thymidine biosynthesis, resulting in megaloblastic anemia and subacute combined degeneration of the spinal cord. It also causes a functional deficiency of folate.

Question 11

water soluble vitamin deficiencies

Folate

Answer 11

Clinical Consequence of Vitamin Deficiency

Lack of folate results in impaired thymidine monophosphate (dTMP) synthesis, with arrest of DNA synthesis in rapidly dividing cells, like hematopoietic cells, resulting in megaloblastic anemia. Pregnant patients require more folate; deficiency results in neurotubule defects, such as spina bifida, in the developing fetus.

Question 12

water soluble vitamin deficiencies

Vitamin C

Answer 12

Clinical Consequence of Vitamin Deficiency

Deficiency can result in scurvy, which is characterized by easy bruising, muscular fatigue, soft swollen gums, hemorrhage, and anemia.

Question 13

Biochemical Function

Thiamine B1

Answer 13

Cofactor for pyruvate and a-ketoglutarate dehydrogenase

Question 14

Biochemical Function

Riboflavin B2

Answer 14

Precursor to the coenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)

Question 15

Biochemical Function

Niacin B3

Answer 15

Required for the production of NAD+ and NADP+ as well as numerous

Question 16

Biochemical Function

Pyridoxine B6

Answer 16

Required for several transaminase and decarboxylation reactions

Question 17

Biochemical Function

Biotin

Answer 17

Required for some carboxylation reactions

Question 18

Biochemical Function

Cobalamin B12

Answer 18

Required by methylmalonyl CoA mutase and methionine synthase

Question 19

Biochemical Function

Folate

Answer 19

Reduced by dihydrofolate reductase to tetrahydrofolate (THF), which functions as a one-carbon donor in many biosynthetic pathways

Question 20

Biochemical Function

Vitamin C

Answer 20

Hydroxylation of proline residues in collagen and aids in iron absorption

Question 21

Lipid Soluble Vitamin Deficiencies

Deficiency results in night blindness, dry eyes leading to corneal damage, and urinary stones

Answer 21

Vitamin A

Question 22

Lipid Soluble Vitamin Deficiencies

Rickets in children results in defective bone ineralization
with a ‘‘squared’’ head, chest deformity, spine abnormalities, and bowing of the legs. In adults, osteomalacia can occur, with weakening of bone and increased incidence of fracture.

Answer 22

Vitamin D

Question 23

Lipid Soluble Vitamin Deficiencies

Rare; however, lack of vitamin E can contribute to the development of atherosclerosis and cardiovascular disease.

Answer 23

Vitamin E

Question 24

Lipid Soluble Vitamin Deficiencies

Deficiency is seen in newborns because vitamin K is produced by the yet undeveloped gastrointestinal flora, resulting in hemorrhage and bleeding diathesis. The blood thinner warfarin, used to treat blood clots, antagonizes the vitamin’s actions.

Answer 24

Vitamin K

Question 25

Biochemical Function

Required for growth and differentiation; required for the production of the light-absorbing vision protein rhodopsin

Answer 25

Vitamin A

Question 26

Biochemical Function

Regulation of gene expression for the absorption of calcium from the gastrointestinal tract

Answer 26

Vitamin D

Question 27

Biochemical Function

Functions as an antioxidant and free radical scavenger

Answer 27

Vitamin E

Question 28

Biochemical Function

Required for the g-carboxylation of coagulation factors II, VII, IX, and X

Answer 28

Vitamin K

Question 29

A normal person refers to a 70-kg individual with a fuel reserve of 30% by weight. The increased reserve of the obese individual is mostly fat. Complete fasts indicate one can live without food, but with water, for about 60 days (theoretically, a 70-kg person has 21 kg of fuel reserve, divided as 15 kg of fat and 6 kg of protein. This approximates 165,840 calories of energy. The daily metabolic need of such a person is about 2620 calories per day, for a survival time of 63 days). Death ensues when ___ ___ (e.g., from brain, heart) start to
be used for energy.

Answer 29

essential proteins

Question 30

Important Mineral Deficiency

Copper

Answer 30

Deficiency results in muscle weakness, neurologic defects, and abnormal collagen cross-linking.

Question 31

Important Mineral Deficiency

Iodine

Answer 31

Deficiency results in goiter and hypothyroidism; uncommon with the advent of iodized salt.

Question 32

Important Mineral Deficiency

Iron

Answer 32

Deficiency results in defective hemoglobin production and developing hypochromic, microcytic anemia.

Question 33

Important Mineral Deficiency

Selenium

Answer 33

Deficiency results in cardiomyopathy (Keshan disease).

Question 34

Important Mineral Deficiency

Zinc

Answer 34

Deficiency results in growth retardation and impaired

wound healing.

Question 35

Copper

Biochemical Function

Answer 35

Component of many oxidases in oxidative metabolism, neurotransmitter synthesis, and collagen synthesis

Question 36

Iodine

Biochemical Function

Answer 36

Essential component of thyroid hormone

Question 37

Iron

Biochemical Function

Answer 37

Essential component of hemoglobin as well as other metalloenzymes

Question 38

Selenium

Biochemical Function

Answer 38

Component of glutathione peroxidase

Question 39

Zinc

Biochemical Function

Answer 39

Component of many oxidases

Question 40

Patients with severe liver disease cannot detoxify __ and thus develop hepatic ____ from the accumulation of ____. ___ is used to treat this condition and reduces ammonia by either increasing bacterial assimilation of ammonia or reducing deamination of nitrogenous compounds.

Answer 40

ammonia
encephalopathy
ammonia in the CNS
Lactulose

Question 41

_____ are common diagnostic markers of liver damage found in serum. The cytosolic alanine aminotransferase (ALT) and aspartate aminotransferase
(AST) are released from dying cells upon insult.

Answer 41

Transaminases

Question 42

The BUN is a widely used measure of the kidney’s functional ability to excrete the ___ waste produced by the body.

Answer 42

nitrogenous

Question 43

EPO, produced by recombinant DNA technology, is used in the management of ___ resulting from kidney failure, hemolytic anemia, or anemia associated with chemotherapy. It is also a blood doping agent in endurance sports such as cycling, rowing, and long-distance running.

Answer 43

anemia

Question 44

5. A 57-year-old alcoholic man with chronic pancreatitis is admitted to the hospital for treatment. The absorption of which one of the following vitamins may be affected with pancreatitis?
(A) Vitamin B12 (cobalamin)
(B) Folic acid
(C) Vitamin B2 (riboflavin)
(D) Vitamin B6 (pyridoxine)
(E) Vitamin D

Answer 44

E. Although alcoholics are often malnourished with various nutrient deficiencies, pancreatitis will affect the role of the exocrine pancreas in the absorption of fat-soluble vitamins. Vitamin D is the only vitamin listed that is fat soluble; the other vitamins listed are water soluble.
With the lack of pancreatic lipase dietary fat cannot be digested, and the fat-soluble vitamins cannot be released from the lipids. The vitamins thus pass through the intestine, nonabsorbed. The other fat-soluble vitamins are vitamins E, K, and A.

Question 45

6. A 54-year-old Native American living on an Indian reservation in southwest Arizona is brought into the clinic by a family member. They are concerned because of impaired memory, diarrhea, and a rash on the face, neck, and dorsum of the hands. Which vitamin deficiency
do these symptoms represent?
(A) Niacin
(B) Cobalamin
(C) Folic acid
(D) Vitamin C
(E) Vitamin E

Answer 45

A. The patient presents with the classic presentation of pellagra, or niacin deficiency, with diarrhea, dementia, and dermatitis. Niacin is synthesized from the essential amino acid tryptophan, which is particularly deficient in corn-based diets. However, niacin is still required in the diet because the amount of niacin derived from tryptophan is insufficient for daily needs. A cobalamin deficiency (vitamin B12) will lead to megaloblastic anemia along with methylmalonic acidemia. Folic acid deficiency often manifests with megaloblastic anemia. Vitamin C deficiency results in scurvy. Vitamin E deficiency is rare and can result in neurologic symptoms.

Question 46

7. A 32-year-old woman presents to the physician with extreme fatigue and vague neurologic complaints. On examination, it is found that she has decreased positional and vibrational sense, and her complete blood count reveals a megaloblastic anemia. She relates a history of gastric resection 4 years ago for severe stomach ulcers. Which vitamin deficiency does this represent?
(A) Vitamin C
(B) Vitamin D
(C) Vitamin K
(D) Vitamin B12
(E) Folate

Answer 46

D. Both folate and vitamin B12 deficiency lead to a megaloblastic anemia secondary to a reduction in DNA synthesis. Only vitamin B12 deficiency causes neurologic dysfunction associated with damage to the dorsal spinal columns. The history of gastric resection is consistent with a deficiency of intrinsic factor required for reabsorption of vitamin B12 in the terminal ileum. Vitamin C, D, and K deficiencies will not lead to megaloblastic anemia.

Question 47

8. A 75-year-old chronic alcoholic man presents to the emergency room after being found unconscious on the floor of his home. On examination, he is found to have a distended abdomen consistent with ascites.Which of the following functions of the liver has been compromised to lead to the finding of abdominal ascites?
   (A) Lipid metabolism
   (B) Albumin synthesis
   (C) Estrogen metabolism
   (D) Alcohol detoxification
   (E) Decreased production of coagulation factors

Answer 47

B. Cirrhosis results in several complications, including ascites, caused by decreased oncotic pressure causing extravasation of intravascular fluid. Albumin is the primary protein that maintains oncotic pressure within the vessels. Albumin is synthesized by the liver, and in malnourished or chronic disease states, such as chronic alcoholism, the liver synthesizes reduced levels of albumin, and hypoalbuminemia results. Decreased production of coagulation factors leads to bleeding problems, not ascites production. Ascites production is not due to problems in lipid metabolism, estrogen metabolism, or alcohol detoxification.

Question 48

9. A 45-year-old alcoholic man walks into the emergency room with a clumsy, wide-based gait and appears confused. He has pronounced nystagmus, and laboratory tests are significant for a metabolic acidosis and a serum blood alcohol level of 0.13. This patient should most probably be treated with IV fluids containing
which of the following?
(A) Thiamine
(B) Riboflavin
(C) Niacin
(D) Pantothenic acid
(E) Biotin

Answer 48

A. Wernicke encephalopathy, with the classic triad of ataxia, confusion, and ophthalmoplegia (and nystagmus), is due to thiamine deficiency. Thiamine is an essential coenzyme in carbohydrate metabolism, including the pentose-phosphate pathway (transketolase) and the TCA cycle (pyruvate dehydrogenase and a-ketoglutarate dehydrogenase). Riboflavin deficiency is possible in malnourished alcoholics, causing cheilosis, glossitis, and corneal changes. Niacin deficiency causes diarrhea, dementia, and dermatitis. Deficiencies of pantothenic acid and biotin are rare, although a biotin deficiency will lead to hypoglycemia and mild ketosis.

Question 49

10. A fourth-year medical student does an international rotation in Sub-Saharan Africa. While immunizing children against polio, he sees hundreds of malnourished children in refugee camps with bloated-appearing abdomens. He learns that they are severely protein deficient because they are fed a diet of cornmeal that is provided by international relief agencies. These children likely suffer from which of the following?
(A) Marasmus
(B) Anorexia nervosa
(C) Bulimia
(D) Kwashiorkor
(E) Cachexia

Answer 49

D. Protein deficiency (but not overall calorie deficiency), as in kwashiorkor, results in a deficiency of visceral proteins, including those in the blood that normally provide oncotic pressure to retain fluid within vessels. As such, patients with kwashiorkor have abdominal bloating secondary to edema. Marasmus is a deficiency of calories and protein; the children in this question are presumably receiving carbohydrate calories through the cornmeal. Anorexia nervosa and bulimia are disorders of self-induced weight loss that are found mostly in developed countries. Cachexia is weight loss associated with cancer.