Biomarkers and Clinical Laboratory Detection of Acute and Chronic Ethanol Use.

BACKGROUND: Ethanol use can lead to many health and socio-economic problems. Early identification of risky drinking behaviors helps provide timely clinical and social interventions. Laboratory testing of biomarkers of ethanol use supports the timely identification of individuals with risky drinking behaviors. This review provides an overview of the utility and limitations of ethanol biomarkers in the clinical laboratory. CONTENT: Direct assessment of ethanol in tissues and body fluids has limited utility due to the pharmacokinetics of ethanol. Therefore, the evaluation of ethanol use relies on nonvolatile metabolites of ethanol (direct biomarkers) and measurement of the physiological response to the toxic metabolites of ethanol (indirect biomarkers). Ethanol biomarkers help monitor both chronic and acute ethanol use. The points discussed here include the clinical utility of ethanol biomarkers, testing modalities used for laboratory assessment, the specimens of choice, limitations, and clinical interpretation of results. Finally, we discuss the ethical principles that should guide physicians and laboratorians when using these tests to evaluate alcohol use. SUMMARY: Indirect biomarkers such as carbohydrate-deficient transferrin, mean corpuscular volume, and liver enzymes activities may suggest heavy ethanol use. They lack sensitivity and specificity for timely detection of risky drinking behavior and have limited utility for acute ethanol use. Direct biomarkers such as ethyl glucuronide, ethyl sulfate, and phosphatidylethanol are considered sensitive and specific for detecting acute and chronic ethanol use. However, laboratory assessment and result interpretation lack standardization, limiting clinical utility. Ethical principles including respect for persons, beneficence, and justice should guide testing.

Elevated serum ferritin is not specific for hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a rare, potentially fatal, syndrome of excessive and ineffective activation of the immune system. The majority of the reported data on HLH is from pediatric patients and lacks specificity. This makes HLH diagnosis challenging especially in adults where HLH is triggered by many conditions and can resemble many disease entities. Elevated ferritin is one of the diagnostic criteria for HLH. We determined the conditions associated with elevated ferritin at our medical center to assess how specific ferritin is for predicting HLH. We retrospectively reviewed all ferritin results >10,000 µg/L in pediatric and adult patients. The most common condition associated with elevated ferritin was hematologic malignancy in adults (25.7%) and HLH in pediatric patients (48.9%). HLH was diagnosed in 14.2% of adults and 48.9% of children with ferritin >10,000 µg/L. Hyperferritinemia occurs in a variety of conditions and is not specific for adult or pediatric HLH. Common causes of elevated ferritin should be considered before entertaining the possibility of HLH, especially in adult patients.

Gabapentin prevalence: clinical and forensic experience in St. Louis, Missouri, USA.

Gabapentin (Neurontin) is an anti-epileptic drug that has had wide off-label prescription use since market release due to presumed negligible abuse potential. However, trends in drug misuse have demonstrated that gabapentin misuse is occurring, particularly in those with a history of opioid misuse. This is concerning, because although gabapentin has no direct ligand activity at opioid receptors, it does potentiate the analgesic effect of opioids, and concurrent use of gabapentin and opioids may increase the risk of respiratory depressive effects of opioids. This study investigates the incidence of gabapentin detected in urine samples collected for clinical drug screening purposes in a local hospital emergency department and in postmortem samples submitted by medical examiners in the St. Louis metropolitan area. The prevalence of gabapentin and co-detected drugs in both populations is contrasted, compared, and discussed. This study found that 30% of urine samples collected from patients with suspected drug intoxication presenting to SSM Health Saint Louis University Hospital, a quaternary care medical center, were positive for gabapentin, and nearly two thirds of those were also positive for oxycodone. Over a 6-month period, the incidence of gabapentin positive postmortem cases increased from 18% to 20%. Nearly all gabapentin positive postmortem cases were also positive for an opioid, the most significant being fentanyl, suggesting that gabapentin misuse may be due to its potentiating effect of opioid drug action. This study also highlights the limited utility of immunoassay-based urine drug screens.