Deck 34: Nitrogen: Metabolic Integration

Question 1

A 33-year-old female patient presented complaining of a tender abdomen and fever. Examination revealed marked abdominal distension, acidosis, and leukocytosis. Laparoscopy revealed that large parts of the small intestine were necrotic and as a consequence, the entire ileum and the proximal portion of her colon were resected. Due to the resulting loss of a particular set of enteroendocrine cells, this patient is most likely to experience which of the following?

A) increased fatty acid content of the feces
B) increased gastric acid secretion
C) increased hypoglycemia during periods of fasting
D) loss of cholecystokinin-induced release of protein tyrosine tyrosine (PYY)
E) loss of ghrelin-mediated appetite induction

Answer 1

loss of cholecystokinin-induced release of protein tyrosine tyrosine (PYY)

Question 2

A 14-year-old boy presents with weight loss and diarrhea. His tongue becomes sore and blistery after eating oatmeal or rye bread, which leads to the diagnosis of celiac disease. The boy and his parents are advised to be sensitive to symptoms of malabsorption of calcium. Which of the following would be a most likely symptom of which the parents should be aware?

A) dysostosis multiplex
B) large muscle tetany
C) megaloblastic anemia
D) methylmalonic acidemia
E) telangiectasias

Answer 2

large muscle tetany

Question 3

As a physician on a mission to treat patients in subSaharan Africa you encounter numerous children with a common cluster of signs and symptoms. These include chronic diarrhea, dizziness, fatigue, delayed wound healing, and muscle wasting. Given the constellation of symptoms in your patients, you make a diagnosis of marasmus. Which of the following is the principal cause of the observed symptoms?

A) adequate carbohydrate and fat but lack of protein
B) adequate caloric intake but a lack of essential fatty acids
C) adequate protein but deficiency in carbohydrate and fat
D) high concentration of total protein causing kidney failure
E) total caloric intake of protein, carbohydrate, and fat far below necessary needs for growth

Answer 3

total caloric intake of protein, carbohydrate, and fat far below necessary needs for growth

Question 4

You are treating a 12-year-old male patient exhibiting severe episodes of hypoglycemia. Measurement of circulating insulin and glucagon levels indicate that they are normal and responsive to cycles of feeding and fasting. The hypoglycemia can most easily be explained as a defect in which of the following processes?

A) adipose tissue HSL activation
B) hepatic gluconeogenesis
C) intestinal gluconeogenesis
D) renal gluconeogenesis
E) skeletal muscle GLUT4 translocation to plasma membrane

Question 5

A healthy 35-year-old man exhibits a peak serum glucose concentration of 215 mg/dL within 30 minutes of participating in a glucose tolerance test involving the consumption of 60 g of glucose. Two hours after ingestion, measurement of his serum glucose concentration shows it to be to 85 mg/dL. The observed decrease is due to the normal responses of tissues to insulin. In addition, part of the reduction is due to uptake and trapping of glucose within the liver cells, which is facilitated by which of the following enzymes?

A) galactokinase
B) glucokinase
C) phosphoenolpyruvate carboxykinase (PEPCK)
D) phosphofructokinase-1 (PFK1)
E) pyruvate dehydrogenase

Question 6

A 9-month-old child is presented to the emergency room by his parents who report that he has been vomiting and has severe diarrhea. The episodes of vomiting began when the mother stopped breastfeeding and switched to the use of child cow's milk. The infant exhibits signs of failure to thrive, weight loss, hepatomegaly, and jaundice. Laboratory tests show elevated blood galactose, hypergalactosuria, and metabolic acidosis with coagulation deficiency characteristic of classic galactosemia. Which of the following is most likely to occur if this child continues to consume cow's milk?

A) anemia
B) blindness
C) hypercoagulopathy
D) renal failure
E) tetanic contractions

Question 7

Prolonged ethanol consumption and subsequent metabolism ultimately leads to a condition referred to as steatohepatitis or more commonly, "fatty liver syndrome." The increased fat deposition in hepatocytes in response to chronic alcohol consumption is the result of which of the following?

A) decreased CYP7A1 activity
B) decreased malonyl-CoA decarboxylase activity
C) increased branched-chain ketoacid dehydrogenase (BCKD) activity
D) increased glycerol-3-phosphate dehydrogenase activity
E) increased HMG-CoA reductase activity

Question 8

Shortly after birth, an infant presents with severe lactic acidemia, hyperammonemia, citrullinemia, and hyperlysinemia with the presence of a-ketoglurate in the urine. Tests are performed to determine where the defect lies that is causing this cluster of symptoms. These tests indicate that the infant does not have a urea cycle defect, nor a defect in fatty acid oxidation. A defect in which of the following metabolic pathways is most likely the cause of this infants symptoms?

A) bile acid synthesis
B) branched-chain amino acid catabolism
C) gluconeogenesis
D) glycogen synthesis
E) glycolysis

Question 9

Which of the following statements concerning total body energy storage is correct?

A) most of the body's energy store is held as carbohydrate
B) most of the body's energy store is held as lipid
C) most of the body's energy store is held as plasma glucose
D) most of the body's energy store is held as protein
E) total body energy storage approximately equals resting metabolic rate

Question 10

During early fasting, glycogen is used as a source of glucose for the blood. After liver glycogen is depleted, which of the following is most likely to contribute to the maintenance of endogenous serum glucose levels?

A) amino acids of muscle proteins are used to synthesize glucose in the brain
B) fatty acids of adipose tissue are converted into glucose in the liver
C) intestinal glutamine is used as a gluconeogenic substrate
D) liver fatty acids are degraded as precursors for blood glucose
E) skeletal muscle glycogen is broken down and the glucose delivered to the blood

Question 11

You are treating a patient who is suffering from the glycogen storage disease known as von Gierke disease. Although the primary defect in this disease is in glucose homeostasis, which of the following other metabolic abnormalities is expected to be found in patients with this disease?

A) hyperammonemia
B) hyperuricemia
C) hypokalemia
D) hypophosphatemia
E) ketoacidosis

Question 12

Following a minor respiratory illness, a seemingly healthy, developmentally normal 15-month-old girl exhibited repeated episodes of severe lethargy and vomiting in the middle of the night. The parents brought the infant to the ER following a seizure. The child was hypoglycemic and was administered 10% dextrose, but remained lethargic. Blood ammonia was high, liver enzymes were slightly elevated, and urine ketones were only barely detectable. A diagnosis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is made. Measurement of which of the following would also be expected in this infant given the current diagnosis?

A) decreased serum urea
B) elevated serum carnitine
C) elevated serum dicarboxylic acids
D) hyperalaninemia
E) hyperuricemia

Question 13

A 7-year-old boy is examined by his pediatrician because of complaints of severe cramping pain in his legs whenever he rides his bike. In addition, he experiences nausea and vomiting during these attacks. The child has noted that the severity of the cramps is most intense after dinners that include baked potatoes or pasta and sometimes bread. Clinical studies undertaken following a treadmill test demonstrate myoglobinuria and hyperuricemia. Given these symptoms, it seems clear that the boy is suffering from Tarui disease. With which of the following symptoms would this disease also be expected to be associated?

A) ataxia
B) decreased creatinine clearance
C) hypercoagulopathy
D) jaundice
E) methylmalonic acidemia

Question 14

A 6-month-old who is failing to thrive is brought to your clinic. Tests reveal hepatosplenomegaly, muscle weakness and atrophy, hypotonia, and decreased deep tendon reflexes. Biopsy of the liver reveals initial stages of cirrhosis due to the accumulation of an abnormal glycogen whose structure resembles amylopectin. These results indicate the child is suffering from Andersen disease. Which of the following would also be expected in this child?

A) aminoaciduria
B) hyperglycemia
C) hyperlipidemia
D) hypoglycemia
E) normal glycemia

Question 15

A 4-month-old white male infant with a temperature of 38.4°C is examined by his pediatrician. His mother indicates that he has had the fever for the past 4 days, been listless, vomiting, and has watery stools. Blood work indicates the infants' blood pH is slightly acidic and shows reduced bicarbonate. Other untoward blood chemistry includes elevated liver enzymes. The child has a protuberant abdomen, thin extremities, and a doll-like face indicative of von Gierke disease. Given this diagnosis, what other deleterious symptom would be expected in this infant?

A) defective hepatic bile acid synthesis
B) defective hepatic fatty acid synthesis
C) depressed respiration rate
D) severe hyperglycemia
E) severe hypoglycemia

Question 16

You are studying fatty acid synthesis in a cell line isolated from a hepatic cancer patient. You discover that addition of glucose 6-phosphate does not lead to an increase in the rate of palmitic acid synthesis as is the situation for normal hepatic cells. This indicates there is a defect in the allosteric regulation of fatty acid synthase (FAS). Which of the following would most likely also be observed in these cells?

A) decreased cholesterol synthesis
B) decreased ketone synthesis
C) decreased protein synthesis
D) increased amino acid oxidation
E) increased glycogen synthesis

Question 17

The Randle hypothesis was proposed to explain the correlation between carbohydrate and lipid metabolic homeostasis and the effect of disruptions in both processes on diabetes and obesity. Which of the following statements best reflects the basis of the Randle hypothesis?

A) an increase in adipocyte volume due to increased lipid storage causes adipocytes to lose their responsiveness to insulin
B) increased circulating free fatty acids in obese individuals impair the ability of insulin to stimulate skeletal muscle cell glucose uptake
C) long-term hyperlipidemia leads to permanent elevation in pancreatic insulin secretion that ultimately causes downregulation of insulin receptors
D) the high level of circulating free fatty acids stimulates the liver to shut off gluconeogenesis that then impairs pancreatic sensing of the need for insulin release
E) the hyperglycemia prevalent in obese individuals activates insulin release from the pancreas, leading to increased adipocyte lipolysis

Question 18

You are treating 46-year-old man who has suffered a heart attack. Measurement of his serum cholesterol level indicates it is 500 mg/dL. His father died at 37 years of age from a massive heart attack, and one of his 2 younger siblings also has an increased serum concentration of total cholesterol. This patient most likely has a defect in LDL receptor function associated with familial hypercholesterolemia (FH). Which of the following additional signs is characteristic in patients with FH?

A) arcus cornea
B) dysostosis multiplex
C) hyperammonemia
D) hypoglycemia
E) renal lithiasis

Question 19

You are treating a 38-year-old man whose chief complaint is occasional right upper quadrant pain. Analysis of blood samples shows elevated aspartate transaminase (AST) and alanine transaminase (ALT). History indicates that these same enzymes have shown elevated levels each of the past 3 years during routine blood work in conjunction with his annual physical examination. His history also indicates reflux esophagitis, hypertension, and hyperlipidemia. You order tests for serologic and biochemical markers for viral hepatitis and autoimmune liver disease and other metabolic liver diseases, but these results are negative. The patient has gained 50 lb since the age of 18. He consumes less than 5 standard alcoholic drinks per week. Which of the following is the most likely diagnosis in this case?

A) familial hypercholesterolemia
B) medium-chain acyl-CoA dehydrogenase deficiency
C) nonalcoholic fatty liver disease
D) Refsum disease
E) type 2 diabetes

Question 20

A 59-year-old male is found unconscious in an alley and rushed to the emergency room (ER). He is disheveled, clad in dirty torn clothing, has filthy hair, and smells of urine and decaying trash. Emanating from the patient is a strong odor of alcohol. From information contained in his wallet, family are contacted and a history reveals that the man has been living on the streets for several years and that he suffers from severe post-traumatic stress disorder (PTSD). Upon entry into the ER he was administered an iv drip of 5% dextrose. Unfortunately the patient never regained consciousness and died within hours of admission to the hospital. Given the patient's condition and history, which of the following was the most likely cause of his death?

A) alcohol poisoning
B) hyperlipidemia
C) protein malnutrition
D) sepsis
E) severe lactic acidosis

Question 21

During the course of normal cellular metabolism, the body generates large quantities of acid. Despite this, normal blood pH is maintained at a slightly alkaline pH of 7.4. Removal of which of the following is most responsible for the maintenance of the alkalinity of extracellular fluids?

A) ammonia
B) carbon dioxide
C) ketones such as acetoacetate
D) lactic acid
E) phosphoric acid