• Lynn M Yee and Danny Wu.
• Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco, San Francisco, California, USA.
• Obstet Gynecol. 2011 Feb 1;117(2 Pt 2):503-6.

BackgroundLabetalol is commonly used for control of hypertension in pregnancy. A component of the workup for new-onset hypertension in pregnancy often includes a urine drug screen. A labetalol metabolite is structurally similar to amphetamine and methamphetamine, thus causing potential cross-reactivity in drug immunoassays.CasesWe present one case of cocaine-induced hypertensive crisis superimposed on chronic hypertension and two cases of severe preeclampsia for which patients required escalating doses of labetalol for hypertension, with subsequent false-positive amphetamine urine drug screen results.ConclusionIn pregnant women requiring labetalol for treatment of hypertensive disease, a urine drug screen may be falsely positive for amphetamines and methamphetamines. Providers should be cognizant of this possibility when interpreting the results of urine drug screens.

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