Clinical Impact of New Reference Intervals for the Roche Prolactin II Immunoassay.

Context: The Roche prolactin immunoassay is used throughout the world. It reports higher values than the Siemens immunoassay but the manufacturer-defined reference intervals are similar. Patient results are often above the Roche upper limit but within the Siemens interval, causing diagnostic confusion.

Mistaken Identity: The Role of Autoantibodies in Endocrine Disease.

Background: Autoimmune endocrine diseases can be thought of as a case of mistaken identity. The immune system mistakenly attacks one's own cells, as if they were foreign, which typically results in endocrine gland hypofunction and inadequate hormone production. Type 1 diabetes mellitus and autoimmune thyroid disorders (Hashimoto and Graves diseases) are the most common autoimmune endocrine disorders, while conditions such as Addison disease are encountered less frequently.

AACC Guidance Document on Laboratory Testing for the Assessment of Preterm Delivery.

Identifying women with preterm labor who will go on to deliver prematurely is crucial to improving outcomes for mother and baby and for saving healthcare resources. Even among those with symptoms, the number of women who deliver preterm is low, and thus the low positive predictive value (PPV) and high negative predictive value (NPV) associated with available biomarkers does not substantially reduce the uncertainty of the clinical diagnosis. While there is some promise in the use of fetal fibronectin (fFN), interleukin 6 (IL-6), or placental alpha microglobulin 1 (PAMG-1) for predicting preterm birth (PTB), their use is unlikely to provide considerable clinical value in populations with a low prevalence.

Validation study of the Access antimüllerian hormone assay for the prediction of poor ovarian response to controlled ovarian stimulation.

Objective: To evaluate the diagnostic performance of the antimüllerian hormone (AMH) level determined using the Access AMH assay for predicting poor ovarian response (POR) defined as ≤4 oocytes retrieved, including the validation of the predefined AMH cutoff of 0.93 ng/mL in both serum and plasma.

Design: Prospective cohort study.

Evaluation of 3 SARS-CoV-2 IgG Antibody Assays and Correlation with Neutralizing Antibodies.

Background: As serologic assays for SARS-CoV-2 become more widely utilized, it is important to understand their performance characteristics and correlation with neutralizing antibodies. We evaluated 3 commonly used SARS-CoV-2 IgG assays (Abbott, DiaSorin, and EUROIMMUN) for clinical sensitivity, specificity, and correlation with neutralizing antibodies, and then compared antibody kinetics during the acute phase of infection.

Methods: Three panels of samples were tested on every assay.

Best practices in mitigating the risk of biotin interference with laboratory testing.

Dietary biotin intake does not typically result in blood biotin concentrations that exceed interference thresholds for in vitro diagnostic tests. However, recent trends of high-dose biotin supplements and clinical trials of very high biotin doses for patients with multiple sclerosis have increased concerns about biotin interference with immunoassays. Estimates of the prevalence of high biotin intake vary, and patients may be unaware that they are taking biotin.

Peritoneal and Pleural Fluid Chemistry Measurements Performed on Three Chemistry Platforms.

Background: Chemistry testing is requested for body fluid (BF) specimens despite the lack of assays approved by the US Food and Drug Administration (FDA). The criteria for categorizing fluids as transudate or exudate are not validated across analyzers.

Objective: To compare BF chemical analysis and classification by different analyzers.

Reference Intervals: Comparison of Calculation Methods and Evaluation of Procedures for Merging Reference Measurements From Two US Medical Centers.

Objectives: To analyze consistency of reference limits and widths of reference intervals (RIs) calculated by six procedures and evaluate a protocol for merging intrainstitutional reference data.

Methods: The differences between reference limits were compared with "optimal" bias goals. Also, widths of the RIs were compared.

Multicenter evaluation of the Access AMH antimüllerian hormone assay for the prediction of antral follicle count and poor ovarian response to controlled ovarian stimulation.

Objective: To evaluate a new fully automated antimüllerian hormone (AMH) assay for prediction of poor ovarian response (POR) to ovarian stimulation defined as four or fewer oocytes retrieved.

Design: Prospective cohort study.

Setting: Thirteen private and academic fertility centers in the United States.

Measuring estrogens in women, men, and children: Recent advances 2012-2017.

The measurement of estrogens is important for diagnosing and monitoring the health of women, men, and children. For example, for postmenopausal women or women undergoing treatment for breast cancer with aromatase inhibitors, the measurement of extremely low concentrations of estrogens in serum, especially estradiol, is problematic but essential for proper medical care. Achieving superb analytical sensitivity and specificity has been and continues to be a challenge for the clinical laboratory, but is a challenge that is being taken seriously.

How low can you go? Analytical performance of five automated testosterone immunoassays.

Background: Testosterone is commonly measured using immunoassays, yet concerns with the accuracy and quality of testing by these methods exist, particularly for low testosterone concentrations. Study objectives were to evaluate selective performance characteristics, including functional sensitivity (FS), of 5 automated immunoassays for total testosterone.

Methods: FS, imprecision, assay interference, limit of blank, linearity, and accuracy were assessed using the Abbott ARCHITECT i2000, SIEMENS ADVIA Centaur and IMMULITE 2000, Beckman Coulter DxI 800, and Roche MODULAR E170.

Does Reverse Triiodothyronine Testing Have Clinical Utility? An Analysis of Practice Variation Based on Order Data from a National Reference Laboratory.

Background: Clinical laboratories are under pressure to increase value by improving test utilization. The clinical utility of reverse triiodothyronine (rT3) is controversial. A study was conducted to identify order patterns that might suggest inappropriate utilization of rT3.

Antimüllerian Hormone Levels Are Not Altered by Glucose Challenge or a Meal.

Background: Measurement of antimüllerian hormone (AMH) is used to assess ovarian reserve. Circulating levels of AMH correlate with antral follicle count, with relatively high levels indicating an ample reserve of primary and preantral follicles in the ovary. AMH levels are stable with dilution and freezer storage, and are not altered by hemolysis or menstrual cycle day in young women of reproductive age.

The significance of reporting to the thousandths place: Figuring out the laboratory limitations.

Objectives: A request to report laboratory values to a specific number of decimal places represents a delicate balance between clinical interpretation of a true analytical change versus laboratory understanding of analytical imprecision and significant figures. Prostate specific antigen (PSA) was used as an example to determine if an immunoassay routinely reported to the hundredths decimal place based on significant figure assessment in our laboratory was capable of providing analytically meaningful results when reported to the thousandths places when requested by clinicians.

Design And Methods: Results of imprecision studies of a representative PSA assay (Roche MODULAR E170) employing two methods of statistical analysis are reported.

Multi-Center Benchmark Study Reveals Significant Variation in Thyroid Testing in United States.

Background: Studies show that a significant portion of laboratory testing is unnecessary. Thyroid tests are some of the most commonly ordered laboratory tests, yet little is known about practice patterns for laboratory testing for thyroid disease. The objective of this study was to collect data on practice patterns for thyroid testing in the United States.

Thyroglobulin Antibody Screen Prior to Mass Spectrometry Provides Measurable Cost Savings and Optimal Laboratory Utilization.

Objectives: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods that allow accurate quantitation of thyroglobulin (Tg) in the presence of Tg antibodies (TgAbs) have recently become available. Due to cost differences between LC-MS/MS and immunoassay, some laboratories now offer a reflex test strategy that uses LC-MS/MS only for TgAb-positive samples. The goal of this study was to examine utilization of Tg testing strategies and cost savings.