Puzzling undetectable haptoglobin in a transfused pregnant patient.

BACKGROUND-AIM: Pregnancy induces physiological changes that can affect serologic and immunologic markers, potentially resulting in lower or undetectable haptoglobin values compared to non-pregnant counterparts. Such variations may lead to inaccurate diagnosis of hemolysis. METHODS: We report a case of a patient in second trimester of pregnancy receiving induction chemotherapy due to B-cell acute lymphocytic leukemia with undetectable haptoglobin levels in a routine laboratory sample collected less than 12 h posttransfusion of red cell unit. Despite undetectable haptoglobin, lactate dehydrogenase (LD) was within reference intervals (RI). The patient was evaluated for acute hemolytic transfusion reaction (AHTR) and followed up. Haptoglobin levels showed an upward trend during follow-up visits, reaching 15 mg/dL, and within RI in the third trimester. RESULTS: The patient did not meet the Center for Disease Control (CDC) criteria for AHTR. Alternative explanations for the observed laboratory findings were explored. Undetectable haptoglobin levels were attributed to various factors, including recent RBC transfusion, pregnancy-related physiological changes, and potential hyperhydration treatment plan due to chemotherapy. CONCLUSION: This case underscores the importance of cautious interpretation of laboratory results in pregnant patients, necessitating trimester-specific reference intervals for haptoglobin. A multidisciplinary approach to patient care is crucial for accurate diagnosis and management.

Resolving icteric interference by a novel photoisomerization device: Bilibox.

Icterus, a phenomenon caused by bilirubin elevation in the blood, is a common endogenous interference in chemistry testing, occurring either spectrally or through chemical reactivity with assay reagents. Often, laboratories have few options other than to dilute or reject samples exceeding icteric thresholds. However, recent studies have optimized in vitro photoisomerization of bilirubin to a 17-minute bilirubin half-life using 500 nm light at 37 °C. Using an enzymatic creatinine assay as a model, due to its prevalence in routine laboratory testing and susceptibility to icteric interference, our study explores the usage of in vitro photoisomerization by replicating these conditions in a device, the Bilibox, as means of resolving icterus in laboratory testing. Left-over icteric and non-icteric clinical samples, collected by lithium heparin vacutainer (n = 10), were analyzed for baseline creatinine, diluted creatinine (1:4 0.9 % NaCl), total bilirubin, direct bilirubin, and hemolysis, icterus and lipemia (HIL) indices. Samples were then placed in the Bilibox in two intervals of 30 min with repeat measurements of the aforementioned analytes. On average, icteric-index, total bilirubin (TBIL), and direct bilirubin (DBIL) decreased by 33.5, 39.1 and 39.9 % respectively following 30 min of Bilibox treatment; and by 47.6 %, 63.7 % and 59.8 % following 60 min. The average percent difference between the pre-exposure diluted and undiluted creatinine was 5.8 %, demonstrating the icterus interference. Following Bilibox treatment, the difference between undiluted (post-exposure) and diluted (pre-exposure) creatinine decreased to 0.02 % (p = 0.0232) and 2.2 % (p = 0.0021) at 30 and 60 min of treatment respectively, demonstrating resolution of interference. Consequently, photoisomerization can be utilized as an additional and reasonably quick method for resolving icterus when dilutional methods cannot be applied.

A preliminary study of hydrocodone and hydromorphone to oxycodone ratios for distinguishing impurities from independent opioid use.

BACKGROUND: Urine drug testing (UDT) monitors prescription compliance and/or drug abuse. However, interpretation of UDT results obtained by liquid chromatography-tandem mass spectrometry (LC-MS-MS) can be complicated by the presence of drug impurities that are detected by highly sensitive methods. Hydrocodone is a drug impurity that can be found as high as 1% in oxycodone pills. OBJECTIVES: We evaluated the frequency and concentration of hydrocodone and its metabolite, hydromorphone, in patients taking oxycodone to check if the ratio of hydrocodone or hydromorphone to oxycodone could distinguish between oxycodone only use from those consuming additional opiates. DESIGN & METHODS: We correlated LC-MS/MS results with medication records of 319 patients with positive oxycodone results over 7 months (4/2021-11/2021). RESULTS: Fifteen of 319 patients with positive oxycodone results were taking oxycodone only. For these 15 patients, the mean ratio of hydrocodone to oxycodone was 0.57% (range 0.05%-3.35%), and the mean ratio of hydromorphone to oxycodone was 0.81% (range 0.18-3.51%). CONCLUSIONS: Hydrocodone and/or hydromorphone are detectable in patients taking only oxycodone and can likely be identified as an impurity if their calculated ratio to oxycodone is <1 %. Further validation of the ratios in a larger sample size is recommended.

Contamination of clinical blood samples with crystalloid solutions: An experimental approach to derive multianalyte delta checks.

BACKGROUND: Laboratorians are left unguided by a paucity of literature on how to configure rules for the detection of intravenous (IV) fluid contamination in blood samples. We designed a study to determine the in vitro effect of increasing blood sample contamination from commonly used crystalloid solutions and how these observations can guide the derivation of multianalyte delta checks to detect such pre-analytical error. METHODS: In this study, we spiked increasing volumes of commonly used IV fluids (normal saline (NS), lactated ringers (LR), and 5% dextrose) into blood samples that were collected from healthy donors. Routine chemistry analytes were measured and compared between neat and contrived samples. From these observations, we derived several permutations of multianalyte delta checks using the basic metabolic panel framework and evaluated rule performance using retrospective data. RESULTS: The wet chemistry experiments showed that increasing the volume of crystalloid solution contamination significantly changed several analytes. Subsequently derived multianalyte delta check procedures were applied to retrospective data. For all IV fluids tested, smaller magnitudes of analyte change resulted in more samples flagged. CONCLUSION: Multianalyte delta checks may be an effective method for the detection of IV fluid contamination.

Rapid serum tubes reduce transport hemolysis and false positive rates for high-sensitivity troponin T.

INTRODUCTION: Hemolysis in the emergency department (ED) can significantly delay results and appropriate action. We evaluated the main sources of hemolysis during sample collection, and to evaluate the use of rapid serum tubes (RST) as a transport hemolysis-mitigating measure for high-sensitivity troponin T (hs-cTnT) testing. METHODS: We examined the effect of tube type, tube fill, types of sample draw and collection methods on hemolysis and hs-cTnT in samples (n = 158) from ED patients. We also compared hs-cTnT values in paired RST and plasma separate tube (PST) samples that were hemolysis-free. RESULTS: The primary source of hemolysis in samples collected in the ED was underfilling tubes. In both tube types, PST and RST, filled tubes showed a median reduction in hemolysis of 69.1 % (p < 0.0001). Blood collected in RST also experienced less hemolysis compared to PST. In hemolysis-free samples, false positive results in PST were noted in patients with hs-cTnT values < 50 ng/l. CONCLUSION: We suggest that proper tube filling during sample collection and use of RST tubes can significantly reduce the effects of hemolysis. In addition, laboratories should be aware that PST tubes have a non-trivial rate of false positives when hs-cTnT < 50 ng/l.

Rapid serum clot tubes reduce haemolysis due to pneumatic tube transport.

AIMS: Pneumatic tube systems (PTSs) are critical for modern hospital operations, allowing for rapid sample transport. Despite widespread use, PTSs can compromise specimen integrity and affect laboratory values. Our objective was to prove that rapid serum clot tubes (RST) provide protective benefits over plasma during PTS transport and can be a practical solution for certain PTS routes. METHODS: In this study, we compared the effects of PTS transport on cell lysis indicators: h-index, lactate dehydrogenase (LDH) and potassium (K+), in RST versus lithium heparin gel separator tubes using 10 volunteers. RESULTS: In comparison with plasma, RST showed a median reduction in PTS-induced haemolysis of 80.4% (p=0.0049), with a reduction in post-PTS median LDH concentration (49.7%, p=0.04) and K+ concentration (50.0%, p=0.0273). CONCLUSION: This study demonstrates RST tubes can significantly reduce PTS-induced haemolysis and can be recommended for poor PTS routes.

Resolving Pseudohyponatremia: Validation of Plasma Sodium on Radiometer ABL800 Blood Gas Analyzers for Immediate Reflex Testing.

OBJECTIVE: To perform validation of plasma sodium on blood gas analyzers to reflexively correct erroneous measurements by ion-selective electrodes (ISEs). METHODS: We compared remnant specimens of whole blood and plasma collected by lithium heparin vacutainer with normal protein concentrations and no lipemia. Whole-blood specimens were tested for sodium concentration on the ABL800 Flex blood gas analyzer, followed by centrifugation for plasma separation, and repeat sodium determination on an aliquot of the plasma only. Also, plasma specimens were analyzed by indirect ISE on the Cobas 8000 series and by direct ISE on the ABL800 Flex for instrument comparison. RESULTS: Plasma aliquots yielded comparable results to the parent whole-blood specimen, with an average change of -1.33 mmol/L (R2 = 0.9727). Comparison of indirect ISE to direct ISE similarly yielded comparable results, with an average change of + 0.8 mmol/L (R2 = 0.9016). CONCLUSION: Plasma is a valid specimen matrix for use on blood gas analyzers for sodium determination, eliminating the need for re-collection of whole-blood specimens from patients with pseudohyponatremia.

The ALT upper reference interval debate: Blame it on the alcohol.

BACKGROUND: In 2017, the American College of Gastroenterology (ACG) and the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition published clinical guidelines recommending the use of alanine aminotransferase (ALT) upper reference limits (URL) of 33, 25, 26, and 22 U/l for men, women, boys, and girls, respectively. This was opposed by laboratory experts who advocated for the use of higher URL of 59, 41, 33, and 24 U/l instead. We suspected that the variable inclusion of individuals who consumed alcohol to be a major contributing source of URL variability and debate. METHODS: Outpatient ALT data (n = 7379) were collected from unique individuals ≥13 y with BMIs of ≥19 and ≤25. A total of 222 (3%) were excluded due to suspected liver disease. Patients were split into a pediatric group (age 13-17 y), an alcohol-restricted adult group (age 18-20 y), and adults with access to alcohol by decade (i.e., age 21-29, 30-39, 40-49, 50-59, 60-69, 70-79, and ≥ 80 y). All ALT values were measured on Roche Cobas 8000 with pyridoxal phosphate and traceable to the IFCC-reference measurement procedure. RESULTS: We derived URL similar to CALIPER for our pediatric population, but closer to ACG-proposed URL in our alcohol-restricted adult group. The URL increased significantly in men and women for all other age groups. CONCLUSIONS: The discrepancy in ALT URL in clinical laboratories may be attributable in part due to the variable inclusion of individuals who recently consumed alcohol in local population derivation studies.

Determination of 97.5th and 99th percentile upper reference limits for heart-type fatty acid-binding protein (H-FABP) in a US population.

BACKGROUND: Heart-type fatty acid binding protein (H-FABP), a low molecular weight protein found primarily in myocardial tissue, has been identified as a potential biomarker in the detection of acute coronary syndrome and acute kidney injury. To further investigate clinical utility, we sought to establish an upper reference limit (URL) of H-FABP within a healthy U.S. METHODS: Serum samples of healthy donors were acquired from the AACC Universal Sample Bank. We analyzed 355 samples for H-FABP concentration using the Randox Laboratories immunoturbidimetric assay on the Roche Cobas 8000 series analyzer. RESULTS: The final sample population consisted of individuals aged 18-74 y, with 170 males and 185 females. The distribution of the population exhibited a strong positive skew, affecting outlier analysis and URL determination. The 97.5th-percentile URL was found to be 7.4 ng/ml (95% CI: 6.3-9.2), while the 99th-percentile URL was 12.1 ng/ml (8.6-14.9). CONCLUSION: As the URL for H-FABP is highly affected by population distribution and outlier removal, final determination for an assay cutoff should be made in the context of clinical utility, either as a standalone assay or in conjunction with other biomarkers, and the desired clinical sensitivity and specificity.

Preventing pseudohyponatremia: Intralipid®-based lipemia cutoffs for sodium are inappropriate.

BACKGROUND: Pseudohyponatremia describes an artifactual decrease in plasma sodium result in samples with high proteins and/or lipids when measured by an indirect ion-selective electrode (ISE) method. We suspected that Intralipid®-based lipemia cutoffs are inappropriate for detecting interfering lipids in human samples and a major contributing factor to the existence of pseudohyponatremia. METHODS: We evaluated 2 approaches to derive a lipemia cutoff for sodium, one in which patient plasma samples were pooled and spiked to simulate hyperlipidemia using Intralipid® (commonly used approach by in-vitro diagnostics manufacturers), and another in which endogenous hyperlipidemic samples (n = 31) were measured by methods not affected by hyperlipidemia (i.e., direct ISE and post-ultracentrifugation indirect ISE). Triglycerides, lipemic index (L-index) and indirect ISE sodium concentrations of samples were measured on Roche Cobas® 8000 and direct ISE on Radiometer® ABL835 Flex analyzers. Endogenous hyperlipidemic samples were also ultracentrifuged on Beckman Coulter® Airfuge to clear excess lipids and re-analyzed for sodium by indirect ISE. RESULTS: We discovered that Intralipid® is not an accurate emulation of the lipemic interference seen in pseudohyponatremia because it showed no effect up to the maximum level of lipemia tested (L-index = 2000). By contrast, endogenous hyperlipidemic samples demonstrated significant deviations in sodium concentration (≥4 mmol/l) when L-index approached or exceeded 700, and a strong positive correlation between L-index and the difference between the indirect and direct methods (i.e., extent of pseudohyponatremia). CONCLUSIONS: Clinical laboratories should lower their tolerance for lipemia from the currently recommended L-index cutoff of 2000 on Roche Cobas 8000®. We recommend reflexing to direct ISE when L-index exceeds 700. Manufacturers and laboratories with other indirect ISE methods should evaluate the effect of lipid interference on their method using hyperlipidemic human samples not Intralipid®.