Assessment of Risk for Interference by Circulating Biotin in Samples Received for High Sensitivity Troponin-T, Thyrotropin, and for Prostate Specific Antigen Testing by Immunoassays.

BACKGROUND: Biotin interference in streptavidin-based immunoassays is known and may lead to erroneous results and thus to diagnostic error. The recent increase in reports of biotin interference in immunoassay-based testing has been attributed to increased intake of biotin supplements by the public and to the high dose biotin therapy in patients with neurological and inherited disorders. Circulating biotin levels greater than 20 ng/mL are reported to exhibit interference in high sensitivity troponin T (hs-TnT), thyroid stimulating hormone (TSH), and in prostate specific antigen (PSA) among other assays when using our Cobas® 6000 immunoassay analyzer (Roche Diagnostics, IN, USA). This study aims to examine the risk for biotin interference among our patient population. METHODS: Serum and plasma leftover samples from 183 different patients were collected following completion of hs-TnT (53 samples), TSH (45 samples), and PSA (85 samples) testing. Aliquots were stored frozen at -20°C until analysis. Biotin concentrations in these samples were measured using an ELISA (ALPCO, Salem, NH, USA) according to the manufacture's protocol. Samples with biotin levels of 20 ng/mL or greater were considered as high-risk samples (HRS) for biotin interference. RESULTS: The overall concentrations of biotin in our patients' samples ranged from 0.02 ng/mL to 11.38 ng/mL (median 0.42 ng/mL). The median and (range) biotin concentrations in hs-TnT, TSH, and PSA samples were 0.27 ng/mL (0.02 - 6.86 ng/mL), 0.39 ng/mL (0.08 - 11.38 ng/mL), and 0.47 ng/mL (0.09 - 7.73 ng/mL), respectively. Although there was no significant difference between biotin levels in samples for TSH or PSA measurement (p = 0.85), biotin in samples for PSA and for hs-TnT and in samples for TSH and hs-TnT were significantly different (p = 0.049 and 0.089), respectively. None of the samples had biotin levels greater than or equal to 20 ng/mL. CONCLUSIONS: Using representative samples with requests for hs-TnT, TSH, and PSA testing, where reliable performance for the selected assays at their lowest measurement range is required for clinical intervention, among our study population the risk was considered minimal as their circulating biotin levels were less than 20 ng/mL. However, educating clinicians and laboratory users regarding the potential of biotin interference is always recommended.

Establishing, harmonizing and analyzing critical values in a large academic health center.

BACKGROUND: No report on establishing critical values (CVs) lists has described a process for harmonizing different lists in a large academic health center or validation on follow-up after 5 years. METHODS: A definition of a critical value was adopted. CVs in use and reporting times for chemistry, hematology and coagulation (CH&C) tests during a 1-week period at one hospital were analyzed prior to the revision and again 5 years later. RESULTS: CVs lists in use by the different campus hospital laboratories were reviewed for compliance with the definition for a critical value. Lists were harmonized with a total of 37 CH&C tests, five of these included adult and either cord blood or neonatal values. Overall, 26 tests were eliminated, 61 individual values were changed and two tests were added. The revised CVs list reduced the number of calls at one primary teaching hospital by 33%. In the next 5-year period, value thresholds changed (n=2) and one value was re-instated (n=1). When retrospectively examined for impact, one value change was considered appropriate. CONCLUSIONS: CVs lists were harmonized among campus hospitals. Tests not considered critical were removed and values adjusted for uniformity. Changes in CVs lists should be evaluated for appropriateness. A process is now in place for periodic review and considerations related to CVs lists.

Patient-derived reference intervals for alkaline phosphatase to support appropriate utility for isoenzymes determinations and hypophosphatasia.

BACKGROUND: Appropriate age- and sex-specific reference intervals for alkaline phosphatase (ALP) are essential to identify patients with hypophosphatasia (low ALP) and to avoid unnecessary ALP isoenzymes analysis (elevated ALP). This study used patient ALP historical data to statistically derive sex- and age-specific reference intervals. METHODS: The ALP values reported as part of clinical management during an 18 month period (from July 2021 to March 2023) were obtained. Following logarithmic transformation of ALP data and repeated removal of outliers, cumulative frequency plots were generated using a modified Hoffmann approach to derive age- and sex-specific reference intervals. RESULTS: Age-specific ALP reference intervals ranged from 110 to 250 and 120 to 295 U/L for males and females <15 days old, 80 to 400 and 90 to 380 U/L for males and females 15 days to 1 year old, 105 to 280 and 90 to 290 U/L for males and females 1 to 10 years old, 75 to 300 and 90 to 300 U/L for males and females 10 to 13 years old, 80 to 300 and 60 to 175 U/L for males and females 13 to 15 years old, 55 to 150 and 60 to 180 U/L for males and females 15 to 18 years old, and 55 to 140 and 60 to 147 U/L for male and female adults, respectively (>18 years old). CONCLUSION: By applying derived ranges, a retrospective review of ALP isoenzymes would eliminate 24.5% of requests. Additionally, 9 neonates would have required investigation for possible hypophosphatasia.

Emerging Biomarkers in the Laboratory and in Practice: A Novel Approach to Diagnosing Heart Failure in Diabetes.

The Biomarkers for the Diagnosis of Heart Failure in Diabetes webinar was hosted by Diabetes Technology Society on September 20, 2023, with the objective to review current evidence and management practices of biomarker screening for heart failure in people with diabetes. The webinar discussed (1) the four stages of heart failure, (2) diabetes and heart failure, (3) natriuretic peptide and troponin for diagnosing heart failure in diabetes, (4) emerging composite and investigational biomarkers for diagnosing heart failure, and (5) prevention of heart failure progression. Experts in heart failure from the fields of clinical chemistry, cardiology, and diabetology presented data about the importance of screening for heart failure as an often-unnoticed complication of people with type 1 and type 2 diabetes.

The Continued Need for the Routine Assessment of Folate Status.

OBJECTIVE: The Choosing Wisely initiative recommended cessation of folate measurement, suggesting folate supplementation in macrocytic anemia. This study reviewed the need for continued blood folate testing at a large SafetyNet county teaching hospital. METHODS: Red blood cell (RBC) folate, vitamin B12, iron, ferritin, and hemoglobin results were obtained for utilization review. RESULTS: Of the 593 RBC folate results, 69 (11.7%) were deficient and 30 (5%) had high values. Collectively, 369 (73.9%) had normal vitamin B12 levels, 342 (70%) had low hemoglobin, 184 (62.5) had normal and 57 (19.4%) had low ferritin, 122 (38.2%) had normal and 188 (59%) had low iron levels. A total of 41 (12%) had normal folate, low ferritin, low hemoglobin, and low iron, suggestive of iron deficiency anemia. There were 11 patients who exhibited low folate, low or normal ferritin, low hemoglobin, and low iron levels, suggesting combined folate and iron deficiency anemias. CONCLUSION: This study highlights the need for institutions to assess the applicability of national recommendations to their local population.

Biomarkers for the Diagnosis of Heart Failure in People with Diabetes: A Consensus Report from Diabetes Technology Society.

Diabetes Technology Society assembled a panel of clinician experts in diabetology, cardiology, clinical chemistry, nephrology, and primary care to review the current evidence on biomarker screening of people with diabetes (PWD) for heart failure (HF), who are, by definition, at risk for HF (Stage A HF). This consensus report reviews features of HF in PWD from the perspectives of 1) epidemiology, 2) classification of stages, 3) pathophysiology, 4) biomarkers for diagnosing, 5) biomarker assays, 6) diagnostic accuracy of biomarkers, 7) benefits of biomarker screening, 8) consensus recommendations for biomarker screening, 9) stratification of Stage B HF, 10) echocardiographic screening, 11) management of Stage A and Stage B HF, and 12) future directions. The Diabetes Technology Society panel recommends 1) biomarker screening with one of two circulating natriuretic peptides (B-type natriuretic peptide or N-terminal prohormone of B-type natriuretic peptide), 2) beginning screening five years following diagnosis of type 1 diabetes (T1D) and at the diagnosis of type 2 diabetes (T2D), 3) beginning routine screening no earlier than at age 30 years for T1D (irrespective of age of diagnosis) and at any age for T2D, 4) screening annually, and 5) testing any time of day. The panel also recommends that an abnormal biomarker test defines asymptomatic preclinical HF (Stage B HF). This diagnosis requires follow-up using transthoracic echocardiography for classification into one of four subcategories of Stage B HF, corresponding to risk of progression to symptomatic clinical HF (Stage C HF). These recommendations will allow identification and management of Stage A and Stage B HF in PWD to prevent progression to Stage C HF or advanced HF (Stage D HF).

Circulating macroprolactin exhibits molecular heterogeneity and is not exclusively an antibody complex.

BACKGROUND: Macroprolactin (macPRL) is considered to be solely a prolactin antibody complex. We examined macPRL heterogeneity in samples from thirteen patients suspected of macroprolactinemia. METHODS: Polyethylene glycol (PEG) precipitation, gel permeation (GPC), protein-G affinity, and Lectin affinity chromatography were used to investigate the nature of macPRL. RESULTS: Using PEG, 8, 3, and 2 samples were macPRL positive, negative, and indeterminate respectively. Using GPC, prolactin appeared at high (H) (≥150 kDa), mid (M) (≥30 < 150 kDa), and low (L) (<30 k Da) forms. For macPRL positive samples, 52.3 to 95.0%, 3.6 to 34.1%, and 1.4 to 34.5% appeared at the (H), (M), and (L) regions respectively, compared with samples negative for macPRL with 1.2 to 5.1%, 60.0 to 79.4%, and 15.4 to 38.9% prolactin activity respectively. macPRL positive samples showed 30.4 to 86.5% binding to protein G column compared with negative samples at 1.2 to 5.1%. GPC-separated forms showed macPRL is heterogenous being either antibody bound (protein G studies) or glycosylated aggregates (lectin studies). Samples with identified macPRL forms were analysed using 4 immunoassay analysers. CONCLUSIONS: Samples with (H) and (M) macPRL forms showed significant positive bias in 2 immunoassays. The study is limited by the small number of samples and a larger scale study is required.

Establish pre-clinical diagnostic efficacy for parathyroid hormone as a point-of-surgery-testing-device (POST).

Measuring the Parathyroid hormone (PTH) levels assists in the investigation and management of patients with parathyroid disorders. Rapid PTH monitoring is a valid tool for accurate assessment intraoperatively. Rapid Electro-Analytical Device (READ) is a point-of-care device that uses impedance change between target and capture probe to assess the PTH concentration in undiluted patient plasma samples. The aim of this work focuses on evaluating the analytical performance of READ platform to Roche analyzer as a prospective clinical validation method. The coefficient of variation (CV) for intra-assay imprecision was < 5% and inter-assay imprecision CV was < 10% for high (942 pg/mL) and low (38.2 pg/mL) PTH concentration. Functional sensitivity defined at 15% CV was 1.9 pg/mL. Results obtained from READ platform correlated well (r = 0.99) with commercially available clinical laboratory method (Roche Diagnostics) to measure PTH concentrations with a turn-around time of less than 15 min. Furthermore, the mean bias of 7.6 pg/mL determined by Bland-Altman analysis, showed good agreement between the two methods. We envision such a sensing system would allow medical practitioners to facilitate targeted interventions, thereby, offering an immediate prognostic approach as the cornerstone to delivering successful treatment for patients suffering from primary hyperparathyroidism.

Complete Depletion of Daratumumab Interference in Serum Samples from Plasma Cell Myeloma Patients Improves the Detection of Endogenous M-Proteins in a Preliminary Study.

BACKGROUND: Therapeutic humanized IgG1 kappa monoclonal antibody (t-mAb), daratumumab (DARA) is a Food and Drug Administration approved drug for the treatment of relapsed/refractory plasma cell myeloma (PCM). DARA appears on serum protein electrophoresis (SPEP) and on serum immunofixation (sIFE) as an IgG kappa monoclonal immunoglobulin protein (M-protein), complicating the assessment of the patients' response to therapy. A more ominous threat to patient safety can occur with the misinterpretation of the presence of a small t-mAb spike as being the residual product of the patient's neoplastic clone, presented either as oligoclonality or new clonality, which could result in incorrect interpretation of failure to achieve remission. METHODS: In this report, we describe a novel and cost-effective technique based on biotinylated recombinant CD38 and streptavidin-coated magnetic beads to capture and remove residual DARA present in PCM patient serum samples. The treated samples are then run like regular samples on SPEP and sIFE. We validated this simple technique in DARA-spiked PCM samples and patient samples on DARA treatment. RESULTS: Our simple capture technique completely extracted DARA in all of the tested serum specimens and allowed the assessment of residual M-protein without DARA interference. The results were reproducible and highly specific for DARA, and did not have any impact on endogenous M-protein migration and quantification by SPEP and sIFE. The cost of this technique is much lower and it can be performed in-house with a very short turnaround time compared to the currently available alternative methods. There is a great need for such reflex technologies to avoid interpretation errors. CONCLUSIONS: This method is an effective way to eliminate DARA interference in SPEP and sIFE, and can be easily implemented in any clinical laboratory without any patent restriction. This simple technique can be adopted for other t-mAbs using their respective ligands and will help to reduce additional doses of toxic treatment and further testing in patients on t-mAbs with a false positive M-protein spike.

Association of a Novel Protocol for Rapid Exclusion of Myocardial Infarction With Resource Use in a US Safety Net Hospital.

Importance: High-sensitivity cardiac troponin T (hs-cTnT) protocols for the evaluation of chest pain in the emergency department (ED) may reduce unnecessary resource use and overcrowding. Objective: To determine whether the implementation of a novel hs-cTnT protocol, which incorporated troponin values drawn at 0, 1, and 3 hours after ED presentation and the modified HEART score (history, electrocardiogram, age, risk factors), was associated with improvements in resource use while maintaining safety. Design, Setting, and Participants: This retrospective cohort study from Parkland Health and Hospital System, a large safety net hospital in Dallas, Texas, included data on 31 543 unique ED encounters in which patients underwent electrocardiographic and troponin testing from January 1, 2017, to October 16, 2018. The hs-cTnT protocol was implemented in December 2017. Main Outcomes and Measures: Resource use outcomes included trends in ED dwell time, troponin to disposition decision time (the difference between the first troponin draw time and the time an order was placed for inpatient admission, admission to observation, or discharge), and final patient disposition. Safety outcomes included readmission for myocardial infarction and death. Results: In 31 543 encounters, mean (SD) patient age was 54 (14.4) years and 14 675 patients (48%) were female. Department dwell time decreased by a mean of -1.09 (95% CI, -2.81 to 0.64) minutes per month in the preintervention period. The decline was steeper after the intervention (-4.69 [95% CI, -9.05 to -0.33] minutes per month) (P for interaction = .007). The troponin to disposition time was increasing in the preintervention period by 1.72 (95% CI, 1.08 to 2.36) minutes per month; postintervention, the mean difference increased more slowly (0.37 [95% CI, -1.25 to 1.99 minutes per month; P value for interaction = .007]). The proportion of patients discharged from the ED increased after the intervention (48% vs 54%, P < .001). Thirty-day major adverse cardiac event rates were low and did not differ before and after the intervention. Conclusions and Relevance: Implementation of a novel protocol incorporating serial hs-cTnT measurements over 3 hours with the Modified HEART Score was associated with reduction in ED dwell times and attenuation of temporal increases in time from troponin measurement to disposition. This or similar protocols to rule out myocardial infarction have the potential to reduce ED overcrowding and improve health care quality while maintaining safety.

Validation and implementation of the fifth-generation high sensitivity Troponin T (hs-TnT) assay at a large teaching county hospital. A laboratory-driven multi-speciality effort.

We describe the validation and implementation of the new 5th generation high sensitivity Troponin T assay (Roche Diagnostics®). In addition to the assay improved sensitivity, the numerical values, reporting units, reference intervals, and critical limits are markedly different. We describe the use of clinical correlation as the basis for implementation and validation of the fifth-generation hs-TnT assay at a large teaching county hospital.

Plasma lactate measurement as an example of encountered gaps between routine clinical laboratory processes and manufactures' sample-handling instructions.

OBJECTIVES: Deviation from manufacturers' pre-analytical sample handling recommendations necessitates extensive validation studies. This report uses plasma lactate testing, where a recommended 15 min room temperature sample handling limit cannot be met by the clinical laboratory, as an example for studies to bridge the gap with practice. DESIGN AND METHODS: Triplicate blood samples were collected from patients (n = 51) with lactate requests by clinicians and from normal volunteers (n = 50). One tube was transported on ice (4 °C), the others were maintained at room temperature (23 °C). Tubes stored at 4 °C were processed at 30 min from collection. Tubes stored at 23 °C were processed at 15 and at 30 min from collection. Lactate levels were measured using Roche Diagnostics Cobas 6000® analyzer. RESULTS: Lactate levels in normal subjects ranged from 0.6 to 3.1 mmol/L (median 1.1). Patient lactate levels ranged from 0.8 to 26.3 mmol/L (median 2.2). Bias in lactate levels following extended storage of samples from both normal subjects and patients ranged from - 1.3 to2.2 and from - 1.0-1.0 mmol/L when stored for 30 min at 23 °C or at 4 °C, respectively. The bias between lactate levels at 30 min at 23 °C and 4 °C was - 1.2 to - 0.5 mmol/L for both populations. Although the bias was not statistically significant for all variables, a clinically significant (>0.2 mmol/L) bias was observed in 28% of normal and 7.0% of patient samples. CONCLUSION: Extending the pre-analytical time to 30 min at 23 °C did not significantly impact clinical utility of lactate measurement in our patient population.

Elevated cerebrospinal fluid beta-2 microglobulin as a tumor marker in a patient with myeloma of the central nervous system.

Myeloma involvement of the nervous system is rare. Extensive literature review revealed only a few cases reported from different parts of the world. The presence of CNS symptoms and detection of plasma cells in the CSF is the usual basis of diagnosis. In addition, immunoelectrophoresis and immunofixation for detection of monoclonal protein confirm the diagnosis in some cases, while some authors used flow cytometry and cytogenetic studies on CSF. Reports of multiple myeloma also include unfavorable cytogenetic abnormalities of chromosome 13. We report a case with relapsed CNS multiple myeloma with the detection of elevated beta-2 microglobulin (beta2M) as a tumor marker in the CSF.

Elevated cerebrospinal fluid b-2 microglobulin as a tumor marker in a patient with myeloma of the central nervous system.

Myeloma involvement of the nervous system is rare. Extensive literature review revealed only a few cases reported from different parts of the world. The presence of CNS symptoms and detection of plasma cells in the CSF is the usual basis of diagnosis. In addition, immunoelectrophoresis and immunofixation for detection of monoclonal protein confirm the diagnosis in some cases, while some authors used flow cytometry and cytogenetic studies on CSF. Reports of multiple myeloma also include unfavorable cytogenetic abnormalities of chromosome 13. We report a case with relapsed CNS multiple myeloma with the detection of elevated b-2 microglobulin (b2M) as a tumor marker in the CSF.

The clinical utility of CK-MB measurement in patients suspected of acute coronary syndrome.

BACKGROUND: This study aims to assess the clinical utility of CK-MB measurement in patients suspected of acute coronary syndrome (ACS). METHODS: All CK-MB and troponin T measurements performed <1h apart during the study period were obtained and analyzed for concordance. A total of 1214 cases with discordant biomarkers results were found. Retrospective review of electronic health records (EHRs) was performed to assess the clinical impact, if any, of the discordant biomarkers results. RESULTS: In 401 cases, CK-MB concentrations were increased whereas troponin T concentrations were negative at <0.01 ng/ml. In this group, clinical interpretations included, rhabdomyolysis, demand ischemia, and drug intoxication. No additional investigations for ACS were conducted in this group. Among the remaining 813 cases, troponin T concentrations were increased in the presence of a normal CK-MB result. In this group, the discordant normal CK-MB lowered suspicion for ACS in only 22 cases (2.7%). Most common interpretations for isolated positive troponin were demand ischemia and impaired renal function. In most cases, discordant CK-MB results were not considered a significant finding. CONCLUSIONS: In the setting of suspected ACS, CK-MB has limited clinical impact when contemporary troponin assay results are available.

Hormonal Replacement in Hypopituitarism in Adults: An Endocrine Society Clinical Practice Guideline.

OBJECTIVE: To formulate clinical practice guidelines for hormonal replacement in hypopituitarism in adults. PARTICIPANTS: The participants include an Endocrine Society-appointed Task Force of six experts, a methodologist, and a medical writer. The American Association for Clinical Chemistry, the Pituitary Society, and the European Society of Endocrinology co-sponsored this guideline. EVIDENCE: The Task Force developed this evidence-based guideline using the Grading of Recommendations, Assessment, Development, and Evaluation system to describe the strength of recommendations and the quality of evidence. The Task Force commissioned two systematic reviews and used the best available evidence from other published systematic reviews and individual studies. CONSENSUS PROCESS: One group meeting, several conference calls, and e-mail communications enabled consensus. Committees and members of the Endocrine Society, the American Association for Clinical Chemistry, the Pituitary Society, and the European Society of Endocrinology reviewed and commented on preliminary drafts of these guidelines. CONCLUSIONS: Using an evidence-based approach, this guideline addresses important clinical issues regarding the evaluation and management of hypopituitarism in adults, including appropriate biochemical assessments, specific therapeutic decisions to decrease the risk of co-morbidities due to hormonal over-replacement or under-replacement, and managing hypopituitarism during pregnancy, pituitary surgery, and other types of surgeries.

Elevated ammonia concentrations: potential for pre-analytical and analytical contributing factors.

BACKGROUND: No study has explored the separate contributions of pre-analytical and analytical factors to hyperammonemia. METHODS: Laboratory information systems were queried for tests of ammonia concentrations over a 12 month period. Pre-analytic (collection to laboratory receipt) and analytic (laboratory receipt to result) elapsed times were determined. RESULTS: Under routine conditions for 3626 tests, normal and elevated results were similarly distributed if the time from venipuncture to result was <120 min. Delays, during analysis performance and in transportation to the laboratory, potentially contributed to hyperammonemia in a small number of samples (n=96, 2.7%). Similar results were obtained from a second hospital with a separate laboratory. CONCLUSIONS: Delays, in either transportation to the laboratory after collection or before completion of analysis, have the potential to elevate ammonia concentrations and may cause pseudo-hyperammonemia. Unexpectedly elevated ammonia concentrations need to be evaluated for errors in sampling handling.