Log in with your email address username.

×

Important notice

doctorportal Learning is on the move as we will be launching a new website very shortly. If you would like to sign up to dp Learning now to register for CPD learning or to use our CPD tracker, please email support@doctorportal.com.au so we can assist you. If you are already signed up to doctorportal Learning, your login will work in the new site so you can continue to enrol for learning, complete an online module, or access your CPD tracker report.

To access and/or sign up for other resources such as Jobs Board, Bookshop or InSight+, please go to www.mja.com.au, or click the relevant menu item and you will be redirected.

All other doctorportal services, such as Find A Doctor, are no longer available.

Mass or molar? Recommendations for reporting concentrations of therapeutic drugs

Units used to report any measurement are an integral component of the result. Errors in communication of units have caused catastrophic failures, for example the Mars Climate Orbiter spacecraft crash in 1999.1 One area of laboratory medicine where different units are in common use is therapeutic drug concentrations, where results for the same drug may be reported in either mass units (eg, mg/L) or molar units (eg, μmol/L) by different laboratories, (see Box for a note on the prefix micro [μ]).

Clinical errors may occur if a result in one unit is interpreted using information expressed in a different unit. This situation may occur when a result is separated from its report (for example, telephoned results), or when a clinician is unaware of unit differences when consulting a textbook, journal article, guideline or website. When assessing results in the toxic range it is more likely that external references will be used, as the therapeutic intervals provided on laboratory reports generally do not indicate the severity of possible toxicity. With the rise of health databases where results from more than one laboratory may be combined, uniformity of reporting takes on…

email