Data on the frequency and causes of icteric interference in clinical chemistry laboratory tests.

The presence of elevated levels of bilirubin (icterus) in serum or plasma specimens has the potential to interfere with clinical chemistry and other laboratory assays. Along with hemolysis and lipemia, icterus represents one of the most common endogenous interferences with laboratory tests. There are two common mechanisms by which icterus can cause assay interference. The first common mechanism is spectral interference due to absorption at wavelengths used in assays by bilirubin and/or bilirubin breakdown products. The second common mechanism involves chemical reaction of bilirubin with the reagents used in some enzymatic assays. Most automated clinical chemistry platforms can perform rapid estimates of indices for hemolysis, icterus, and lipemia (HIL), typically by measuring absorbance at wavelengths impacted by these interferences. The data in this article provides results from a detailed 12-month retrospective review of icteric indices and the impact on 114 clinical chemistry assays at an academic medical center in the United States. The data include 414,502 specimens from 94,081 unique patients (51,851 females; 42,230 males), with a total of 2,791,591 discrete clinical chemistry assays performed on the specimens. Detailed chart review was performed for all patients who had one or more specimens with an icteric index of 40 or higher ('severe icterus'), including determination of the medical diagnoses likely causing icterus and the mortality of these patients within 1 and 3 years following laboratory testing. Data for all specimens include patient location at time of testing (emergency department, inpatient unit, or outpatient site), sex, age, HIL indices, specific clinical chemistry assays performed, and number of times specimens had icteric indices exceeding the icteric index threshold in the package inserts for the clinical chemistry assays performed. The dataset reported is related to the research entitled "Frequency of Icteric Interference in Clinical Chemistry Laboratory Tests and Causes of Severe Icterus" [S. Mainali, A.E. Merrill, M.D. Krasowski, Frequency of icteric interference in clinical chemistry laboratory tests and causes of severe icterus, Pract. Lab. Med. (2021) 27: e00259].

Frequency of icteric interference in clinical chemistry laboratory tests and causes of severe icterus.

OBJECTIVES: The aims of this study were to identify the causes of severe icterus in an academic medical center patient population and to assess the impact of icterus on clinical chemistry testing using assay package insert thresholds. DESIGN: and Methods: In this retrospective study at an academic medical center core clinical laboratory, icteric, hemolysis, and lipemia indices were available for all serum and plasma chemistry specimens analyzed on Roche Diagnostics cobas 8000 analyzers over a 12-month period, encompassing 414,502 specimens from 94,081 unique patients (51,851 females; 42,230 males) including children, inpatient, outpatient, and emergency department patients. Extensive chart review was done for all 57 patients (4 pediatric, 53 adult; 534 total specimens) who had one or more samples with an icteric index of 40 or higher (defined as severe icterus). RESULTS: Specimen icteric index exceeded package insert icteric index thresholds in 0.14% of clinical chemistry assays, with the highest number of instances for creatinine (1358 samples, 0.6% of total tests), total protein (1194 samples, 2.2%), and ammonia (161 samples, 3.9%). The 57 patients with an icteric index of 40 or higher accounted for 49.7% of all instances where the icteric index exceeded the specific assay package insert limit. The most common etiologies of this group of 57 patients were alcohol-related liver disease (34 patients), biliary tract disease (7 patients), and neoplasms (6 patients). CONCLUSIONS: Approximately half of all instances where specimen icteric index exceeded assay package insert thresholds occurred in a small cohort of patients with severe liver/biliary tract disease.

Frequency and causes of lipemia interference of clinical chemistry laboratory tests.

OBJECTIVES: The aims of this study were to identify the causes of severe lipemia in an academic medical center patient population and to determine the relationship between lipemia and hemolysis. DESIGN AND METHODS: Retrospective study was done on the data from the core clinical laboratory at an academic medical center. Lipemic indices were available for all chemistry specimens analyzed over a 16-month period (n=552,029 specimens) and for serum/plasma triglycerides concentrations ordered for clinical purposes over a 16-year period (n=393,085 specimens). Analysis was performed on Roche Diagnostics cobas 8000 analyzers. Extensive chart review was done for all specimens with lipemic index greater than 500 (severely lipemic) and for all specimens with serum/plasma triglycerides greater than 2000 mg/dL. We also determined the relationship between lipemia and hemolysis. RESULTS: The most frequent suspected causes of very high lipemic index (>500) were found to be lipid-containing intravenous infusions (54.4% of total; fat emulsions for parenteral nutrition - 47%; propofol -7.4%) and diabetes mellitus (25% of total, mainly type 2). The most frequent suspected causes of very elevated serum/plasma triglycerides (>2000 mg/dL) was diabetes mellitus (64%, mainly type 2) and hyperlipidemia (16.9%). The frequency of hemolysis increased with increasing lipemic index. CONCLUSIONS: Intravenous lipid infusions and type 2 diabetes were the most common causes of severe lipemia in this study at an academic medical center. Given that iatrogenic factors are the most common cause of severe lipemia, education and intervention may be helpful in reducing frequency of severe lipemia in patient specimens.