A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
An otherwise healthy 15-year-old girl is brought to the physician for evaluation of severe acne that involves her face, chest, and back. It has not improved with her current combination therapy of oral cephalexin and topical benzoyl peroxide. She is sexually active with one male partner, and they use condoms consistently. Facial scarring and numerous comedones are present, with sebaceous skin lesions on her face, chest, and back. Which of the following is indicated prior to initiating the appropriate treatment in this patient?
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A
Perform quantitative beta-hCG assayCorrect. Quantitative beta-hCG is required prior to initiating isotretinoin (per iPLEDGE) because the drug is severely teratogenic and would cause major malformations if used in pregnancy.
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B
Switch cephalexin to doxycyclineIncorrect. Doxycycline is an alternative oral antibiotic but switching is not the next step — severe scarring acne refractory to antibiotic-based combo therapy warrants isotretinoin, not another antibiotic.
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C
Evaluate color visionIncorrect. Color vision testing is screened before starting ethambutol (for optic neuritis), not isotretinoin.
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D
Measure serum DHEA-S and testosterone levelsIncorrect. Measuring DHEA-S/testosterone is part of the workup for hyperandrogenism (e.g., PCOS), warranted when there is hirsutism, virilization, or oligomenorrhea — not present here.
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E
Obtain baseline liver function tests and fasting lipid panelIncorrect. Baseline LFTs and lipids are part of the isotretinoin workup and monitoring, but they are not the critical pre-treatment requirement — pregnancy testing per iPLEDGE is the indispensable step prior to initiation.
↑ Tap an answer to reveal the reasoning
Answer: A. A 15-year-old with severe nodulocystic acne (with scarring) refractory to oral antibiotics + topical benzoyl peroxide meets criteria for **isotretinoin (oral retinoid)**. Isotretinoin is highly teratogenic — Category X — and is associated with severe craniofacial, cardiac, and CNS malformations. Because she is sexually active, the FDA-mandated **iPLEDGE program** requires two negative pregnancy tests before initiating therapy, monthly pregnancy tests during treatment, and confirmed use of two forms of contraception. Therefore the most important pre-treatment step is a **quantitative beta-hCG**.
Isotretinoin also requires monitoring of LFTs and lipid panel (it elevates triglycerides), but the teratogenicity check is the most critical safety prerequisite.
Key pearl: any severe, scarring, or treatment-resistant acne is an indication for isotretinoin, but iPLEDGE compliance (pregnancy testing + two forms of contraception) is non-negotiable for female patients of reproductive potential.
**Why each option:**
**A.** Quantitative beta-hCG is required prior to initiating isotretinoin (per iPLEDGE) because the drug is severely teratogenic and would cause major malformations if used in pregnancy.
**B.** Doxycycline is an alternative oral antibiotic but switching is not the next step — severe scarring acne refractory to antibiotic-based combo therapy warrants isotretinoin, not another antibiotic.
**C.** Color vision testing is screened before starting ethambutol (for optic neuritis), not isotretinoin.
**D.** Measuring DHEA-S/testosterone is part of the workup for hyperandrogenism (e.g., PCOS), warranted when there is hirsutism, virilization, or oligomenorrhea — not present here.