Metabolism — MCQs

A 54-year-old woman presents with increasing shortness of breath on exertion for the past few months. She also complains of associated fatigue and some balance issues. The patient denies swelling of her feet and difficulty breathing at night or while lying down. Physical examination is significant for conjunctival pallor. A peripheral blood smear reveals macrocytosis and hypersegmented granulocytes. Which of the following substances, if elevated in this patient’s blood, would support the diagnosis of vitamin B12 deficiency?

A 35-year-old man comes to the physician because of worsening pain in his lower back, knees, and shoulders over the past few years. He used to be able to touch his fingers to his toes while standing; now he has difficulty touching his shins. He is wearing a shirt with dark brown stains around the armpits. Physical examination shows bluish-brown sclerae and thickening of the external ear. The range of motion of the affected joints is decreased. X-rays of the spine show calcification of multiple lumbar intervertebral discs. The patient's condition is most likely caused by impaired metabolism of which of the following?

A 15-year-old boy presents with sudden onset right sided weakness of his arm and face and difficulty speaking. He denies any problems with hearing or comprehension. The patient has no history of chest pain, hypertension, or diabetes mellitus. No significant past medical history. The patient is afebrile, and vital signs are within normal limits. On physical examination, the patient is thin, with long arms and slender fingers. There is a right-sided facial droop present. Ophthalmic examination reveals a dislocated lens in the right eye. Strength is 3 out of 5 in the right upper extremity, and there is a positive Babinski reflex on the right. The CT scan of the head shows no evidence of hemorrhage. Laboratory findings are significant for increased concentrations of a metabolic intermediate in his serum and urine. Which of the following enzymes is most likely deficient in this patient?

A 3-month-old boy is brought to his pediatrician's office for follow-up after being hospitalized for metabolic decompensation. The patient had presented with poor feeding, vomiting, lethargy, and a sweet maple syrup odor to his urine. Laboratory studies during admission showed elevated branched-chain amino acids and ketoacids in blood and urine. The patient was initially managed with protein restriction and has now stabilized. The patient's mother mentions that her brother had similar symptoms as a child and requires a special diet. As the patient recovers and protein intake is gradually increased, which of the following amino acids should be most carefully monitored and potentially supplemented to maintain proper growth and development?

A 9-month-old infant presents to your office for a check-up. Exam reveals developmental delay, microcephaly, and a mousy odor to his breath. You should be concerned that the infant may have which of the following?

A 2-year-old girl presented to the emergency department after a generalized tonic-clonic seizure that lasted one minute, an hour ago. She has been in good health since birth and has no history of convulsions in the past. She has been sick with an upper respiratory tract infection for the last 2 days, and her parents have been medicating her at home for a subjective fever. Her blood pressure is 109/51 mm Hg, pulse rate is 180/min, temperature is 38.9°C (102.0°F), and oxygen saturation is 98% on room air. The child is sleepy and ill-appearing. The cardiovascular, respiratory, and abdominal examinations are unremarkable. Blood glucose level is 50 mg/dL. Three boluses of IV dextrose are given, but the patient remains drowsy. CXR is normal. After a few hours, her clinical condition deteriorates with associated respiratory failure that requires intubation and mechanical ventilation. Liver function tests reveal AST > 3,000 U/L, ALT > 2,200 U/L, and INR > 3.0. Further testing ruled out hepatitis A, B, and C, and CMV infection. CT scan of the brain was normal. What is the most likely cause of her condition?

A 45-year-old man presents to his primary care physician for a general checkup. The patient has no complaints, but is overweight by 20 lbs. The physician orders outpatient labs which come back with an elevated total bilirubin. Concerned, the PCP orders further labs which show: total bilirubin: 2.4, direct bilirubin 0.6, indirect bilirubin 1.8. Which of the following are true about this patient's condition?

A 38-year-old man with chronic hepatitis C comes to the physician because of a 10-day history of darkening of his skin and painless blisters. He started working as a landscaper 2 weeks ago. He drinks 2 beers every night and occasionally more on the weekends. Examination shows bullae and oozing erosions in different stages of healing on his arms, dorsal hands, and face. There are atrophic white scars and patches of hyperpigmented skin on the arms and face. This patient's skin findings are most likely associated with increased concentration of which of the following?

A 41-year-old man presents to his primary care provider complaining of a blistering skin rash. He was out in the sun with his family at a baseball game several days ago. Later that evening he developed a severe blistering rash on his forearms, back of his neck, and legs. He denies fevers, chills, malaise, abdominal pain, or chest pain. He denies dysuria or a change in his bowel patterns but does report that his urine has occasionally appeared brown over the past few months. His family history is notable for hemochromatosis in his father. He does not smoke or drink alcohol. On examination, he has small ruptured blisters diffusely across his forearms, back of his neck, and lower legs. This patient most likely has a condition caused by a defect in an enzyme that metabolizes which of the following compounds?

A 38-year-old man presents to a fertility specialist. He is concerned that he is infertile. His wife had two children from a previous marriage and has regular menses. They have been married three years and have been trying to conceive for the past two. His vitals are normal. Physical exam reveals bilateral gynecomastia, elongated limbs, and small testicles. Levels of plasma gonadotropins are elevated. Which of the following is likely to be also elevated in this patient?