Effect of residual detergents in specimen collection containers on routine serum biochemical analytes

The use of Teepol, Lysol and sodium hypochlorite are frequent in reusing of specimen collection tubes by the state hospitals in Sri Lanka. Detergent residue in collection tubes is thought to be the reason for uncertain results in the recent past. This raised a concern to evaluate the effect of washing of the specimen collection tubes by various detergents on serum creatinine, aspartate transaminase (AST), Na⁺ and K⁺. Three sets of newly purchased glass Khan tubes were washed using Teepol, Lysol (concentration of 1%), and sodium hypochlorite (0.1 %) adhering to World Health Organization protocol. Blood from a single donor was aliquoted to a detergent washed tubes (test) and to a newly purchased plain glass Khan tube (control). Both were tested for serum creatinine, AST, Na⁺ and K⁺. A sample size of 20 was analyzed for each detergent-washed tube. There was no significant difference in serum creatinine, AST and K⁺ when Teepol, Lysol or sodium hypochlorite washed tubes were used in sequence (p>0.05). Na⁺ concentrations measured in serum was significantly different in specimens collected to Lysol-washed tubes (p<0.05). The Lysol-washed tubes were significantly contaminated with detergent residues. In conclusion, domestic detergents (Teepol, Lysol and sodium hypochlorite) don’t impart a significant effect on tested analytes if the cleansing is done according to guidelines by World Health Organization. However, newly purchased tubes are recommended in critical investigations such as serum electrolytes to improve the accuracy of laboratory reports.