Chapter review
Bring the chapter together
Start with the case synthesis, answered in 3 separate parts, then work through mixed case-based questions. Every answer explains the clue that matters and why the closest alternative fails.
Case synthesis
Bringing it together: three exposures, one method
Three patients arrive the same night. A firefighter is comatose with a normal PaO₂ and a severe lactic acidosis. A man who drank from an antifreeze bottle is confused with jaw spasms, an anion gap of 30 and an osmolal gap of 32. A thin young woman who binges and vomits has knuckle calluses, swollen parotids and a potassium of 2.8.
1. Name the agent from the exposure
Match each exposure to its agent.
2. Name the molecular target
Which targets are hit?
3. Predict the confirming lab
Which lab confirms each?
Mixed case review
Morphology, mechanism and application. Some items need two sections at once.
- Q1Vitamin D deficiency, osteomalaciaConnects 6.5Midterm sim. p.9L6 p.39–40
A 45-year-old woman with long-standing Crohn disease and severe fat malabsorption fractures her femoral neck after a minor contusion.
A deficiency of which vitamin is most likely?
- Q2ScurvyConnects 6.4 + 6.5Midterm sim. p.10L6 p.46
A 15-year-old boy has tooth loss, gingivitis, skin hemorrhages, recurrent infections and poor wound healing. He is in the 20th percentile for height and 10th for weight.
Which condition best fits?
- Q3Vitamin A deficiencyConnects 6.5Midterm sim. p.10L6 p.38
A 40-year-old malnourished woman has a six-month history of night blindness. Examination shows keratomalacia and corneal ulceration.
Which deficiency is suspected?
- Q4B12 vs folateConnects 6.5Midterm sim. p.10–11L6 p.44–45
A 50-year-old woman has easy fatigability, a smooth sore tongue, numbness and tingling of the feet, and leg weakness. A megaloblastic anemia is not reversed by folate.
Which deficiency is most likely?
- Q5Zinc deficiency (Chapter II crossover)Connects 6.6Ch. II cases p.10L6 p.47
A 38-year-old man with Crohn disease and repeated small-bowel resections has hair loss, a rash around the mouth, and a metallic taste.
He is most likely deficient in which element?
- Q6Alcohol, NADH and steatosisConnects 6.1L6 p.5, 7
A man with chronic alcohol use has an enlarged, fatty liver and high serum triglycerides.
Which consequence of the raised NADH/NAD⁺ ratio most directly causes the fatty liver?
- Q7CO vs cyanideConnects 6.2L6 p.12–13L1 p.15
Two people are rescued from a house fire. Both have a normal PaO₂ and lactic acidosis. One has a cherry-red appearance and an elevated carboxyhemoglobin; the other has bright red venous blood and lactate far out of proportion to the carboxyhemoglobin.
What poisons the second patient's cells?
- Q8Lead vs iron deficiencyConnects 6.2L6 p.12
A toddler in an old house has a microcytic anemia. One smear shows coarse basophilic stippling; serum ferritin is normal.
What distinguishes this from iron-deficiency anemia?
- Q9Bulimia: hypokalemic metabolic alkalosisConnects 6.4L6 p.34
A normal-weight young woman with knuckle calluses and parotid swelling has been self-inducing vomiting for months.
Which acid–base and potassium picture fits?
- Q10Anorexia, low estrogen, osteoporosisConnects 6.4L6 p.32
A 19-year-old woman with anorexia nervosa and amenorrhea has a low bone density for her age.
Which mechanism best explains the osteoporosis?
- Q11Radiation: lymphopenia firstConnects 6.3L6 p.25
A worker is exposed to a whole-body dose of ionizing radiation.
Which blood change appears earliest?
- Q12Copper, lysyl oxidase, MenkesConnects 6.6L6 p.47Ref. · Menkes disease
An infant fed an unsupplemented diet has an iron-unresponsive microcytic anemia, brittle depigmented hair and a tortuous, aneurysmal aorta.
Which enzyme is most directly deficient in its cofactor?
- Q13Acetaminophen risk factorsConnects 6.1L6 p.10L1 p.22
A chronic drinker who has been fasting takes a moderate overdose of acetaminophen and develops severe hepatotoxicity.
Why is he at higher risk than expected for the dose?
- Q14Methanol and formic acidConnects 6.2L6 p.13
A man who drank windshield washer fluid develops a raised-anion-gap metabolic acidosis and loss of vision.
Which metabolite is responsible?
- Q15Vitamin E vs B12Connects 6.5L6 p.41, 44Ch. VI cases p.7
A man with chronic pancreatitis has ataxia and loss of proprioception. His anemia is hemolytic with a normal MCV.
Which deficiency fits better than B12, and why?
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Timed practice