UNRESTRICTED AVAILABILITY OF A PLASMA PARACETAMOL ASSAY SERVICE RESULTING IN AN INCREASED NUMBER OF INAPPROPRIATE REQUESTS

Previously, prior approval from the on-call chemical pathologist was r equired in our hospital for plasma paracetamol measurements. However, since May 1992, there have been no restrictions on ordering this assay . We have assessed the consequences of this policy change by comparing the number and appropriateness of requests for plasma paracetamol mea surements in Chinese patients admitted to our hospital with acute pois oning over two six-month periods (July-December) in 1991 and 1993. Req uests were considered appropriate if paracetamol ingestion was suspect ed or unknown drugs were ingested. The number of patients having plasm a paracetamol concentrations assayed increased from 51 in 1991 to 141 in 1993 (176%). The corresponding increase in the number of Chinese pa tients admitted to two of our eight general wards with poisoning was e stimated to be 93%. The of 'appropriate' plasma measurements dropped f rom 55% in 1991 to 21% in 1993. Eight patients had plasma paracetamol concentrations above the recommended treatment line; they were all fro m the group in whom the requests were appropriate. Three of the 135 pa tients in the group with 'inappropriate' requests were found to have s lightly elevated but far from toxic plasma paracetamol concentrations. Unrestricted availability of paracetamol measurements resulted in an increase in the number of inappropriate requests.