Investigating the relationship between false positive results of serum levels of acetaminophen with serum urea and creatinine levels in renal failure patients: with knowledge that acetaminophen has not been ingested

Abstract

Introduction: Suspected poisoning with an unknown agent, usually develop renal insufficiency and uremia, which may lead to false-positive serum acetaminophen levels measured by spectrophotometry method in the laboratory. Aim: Evaluation of the relationship between false positive results of serum acetaminophen levels with serum urea and creatinine concentrations in patients with renal insufficiency. Material and methods: 30 patients with ESRD (end-stage renal disease) who undergone hemodialysis, were included in the study. After obtaining informed consent, an additional blood sample of 5 cc was taken from the patients before dialysis. To investigate the patient not taking acetaminophen, the O-Cresol diagnostic test was used and spectrophotometry method was performed to determine the serum concentration of acetaminophen. The obtained concentration of acetaminophen was then compared with the levels of creatinine and urea in the blood. Results: Despite not taking acetaminophen, the serum level of acetaminophen with a mean of 65.73 ± 9.49 µg / ml were high in these patients. Creatinine levels with a mean of 8.83 ± 2.74 mg/dl and urea levels with a mean of 130.67 ± 26.78 mg/dl were abnormal in all patients. The mean glomerular filtration rate was 2/47 ± 6/06 ml/min/1.73m2. However, there was no significant relationship between creatinine, blood urea, and glomerular filtration rate with acetaminophen serum level (P> 0/05). Conclusions: It seems that despite the lack of acetaminophen usage and also the negative reports of O-Cresol diagnostic test in patients with chronic renal failure undergone hemodialysis, in addition to urea and creatinine, various other toxins may increase and interfere with the spectrophotometric method, resulting in pseudo high levels of acetaminophen in the blood.