PMC6816131_01
Electrocardiogram (ECG) taken approximately 2 h after ingestion of hydroxychloroquine. The ECG shows sinus rhythm with a rate of 91 bpm, a QRS duration of 132 msec, and a corrected QT interval (QTc) of 728 msec.
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Her ECG taken approximately 2 h after ingestion showed sinus rhythm with HR of 91 bpm, QRS duration of 132 msec (normal range: 120 msec or less), and a corrected QT interval (QTc) of 728 msec (normal range: 440 msec or less; see Fig. 1). Her initial laboratory studies were notable for a plasma potassium of 3.0 mmol/L (normal range: 3.5-5.0 mmol/L) and a whole blood lactate of 2.5 mmol/L (normal range: 0.5-2.0 mmol/L).
Electrocardiogram showing sinus rhythm with a rate of 82 bpm and a QRS of 112 msec. The QTc was recorded by the machine as 320 msec but is closer to 600 msec by manual measurement.
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An ECG obtained shortly after arrival showed sinus rhythm with a rate of 82 bpm, and a QRS of 112 msec (see Fig. 2).
Representative examples of interference or errors produced by varying concentrations of hydroxychloroquine spiked in urine. (A) Buprenorphine and (B) cotinine screens shows decrease in relative absorbance relative to baseline from hydroxychloroquine concentrations ranging from 1 to 500 mg/L. For both assays, a hydroxychloroquine concentration of 1000 mg/L produces an absorbance error on the instrument. (C) Oxycodone screen shows no effect of hydroxychloroquine concentrations from 1 to 500 mg/L but does have an absorbance error at 1000 mg/L. See Table 1 for details on assay versions.
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Absorbance alarms and/or interference bias were clearly evident in 6 of the assays (Fig. 3, Fig. 4show representative data for each of these 6 drugs). Buprenorphine, cotinine, and oxycodone qualitative screens all showed absorbance alarm at 1000 mg/L; buprenorphine and cotinine additionally showed negative bias related to control (not spiked with hydroxychloroquine) at all concentrations starting at 1 mg/L (Fig. 3).
Representative examples of interference produced by hydroxychloroquine spiked in urine. (A) Urine myoglobin (quantitative assay) shows negative bias from hydroxychloroquine, especially evident at hydroxychloroquine concentrations of 500 and 1000 mg/L. (B) Urine microalbumin (quantitative assay) shows biphasic interference, with negative bias evident at 1-100 mg/L and a positive bias at 1000 mg/L. (C) THC screen shows slight positive bias from hydroxychloroquine, especially at hydroxychloroquine concentrations of 500 and 1000 mg/L. See Table 1 for details on assay versions.
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Myoglobin, microalbumin, and THC screen were examples of assays that showed evident bias but did not register any instrument alarm or error even up to 1000 mg/L (Fig. 4). A urine specimen pool with myoglobin concentration of 1008 ng/mL showed progressive negative bias with an apparent myoglobin concentration of 599 ng/mL when the sample was spiked with hydroxychloroquine concentration of 1000 mg/L (Fig. 4A). Microalbumin showed biphasic effects of hydroxychloroquine with negative bias at lower concentrations and a positive bias at higher concentrations (Fig. 4B); this was consistent across 4 urine specimen pools with varying baseline microalbumin concentrations. The THC screen showed slight positive bias (Fig. 4C); this would have potential to impact positive/negative results in specimens with baseline reactivity just below positive cutoff in the absence of hydroxychloroquine.