Use of a plasma salicylate assay service in a medical unit in Hong Kong: a follow-up study.

We have previously showed that routine screening of all patients with acute poisoning for salicylates in Hong Kong is unnecessary. We suggested that plasma measurements should be restricted to those suspected of having ingested salicylates. Our results and suggestion have since been presented and discussed in our medical unit meetings. The impact of our suggestion on the use of our plasma salicylate assay service was determined in this follow-up study of 196 patients presenting between October 1994 and April 1995. In 24 patients (12%), ingestion of salicylates was suspected, and of these, 3 (12.5%) had detectable plasma salicylate concentrations (> or = 0.3 mmol/L). The incidence in those who had taken identifiable drugs, unidentifiable drugs but nature known, and topical medicaments was 20%, 0% and 29%, respectively. Urinary alkalinization was necessary in the only patient with moderate to severe symptoms. In 172 patients (88%), ingestion of salicylates was not suspected; 3 (1.7%) had plasma salicylate concentrations of 0.47-2.05 mmol/L but mild symptoms only. We confirmed that routine screening for salicylates in all patients with acute poisoning was unnecessary. Despite our suggestion, 88% of plasma salicylate measurements in this follow-up study (76% in January 1992-June 1993) involved patients not suspected of having ingested salicylates.