Paging the Lab: “This Endocrine Result Doesn’t Make Sense”

On Sunday, an AACC University session organized by Andrew Don-Wauchope, MB.BCh, MD, FRCP, from LifeLabs, along with a cadre of subject matter experts, enlightened an audience with an endless supply of practical knowledge and applications of endocrine testing in a session titled, “Interpretation of Endocrinology Assays: A Guide for the Clinical Laboratorian to Communicate Method Variation, Reference Intervals, and Dynamic Testing Cut-offs to Endocrinologists and other Cl.”

Medicine is heavily reliant on the clinical laboratory to provide accurate and reliable laboratory results to render a diagnosis, prognosis, or decision on an appropriate treatment plan. This is ever truer when it comes to interrogating endocrine diseases. The primary purpose of this session was to educate clinical laboratorians on a wide range of endocrine diseases and how they are diagnosed—all with the goal of developing stronger partnerships with the clinical endocrinologists and patients they serve.

In addition to Don-Wauchope, speakers Grace Kroner, PhD, from Cleveland Clinic; Julie Shaw, PhD, from The Ottawa Hospital, the University of Ottawa, and the Eastern Ontario Regional Laboratories Association; and Matthew Gilbert, DO, from the University of Vermont Medical Center, presented teaching cases in an interactive format, stopping to poll the attendees about practices at their own institutions. Cases highlighted the utilization of endocrine-related laboratory tests, from salivary cortisol, 24-hour urine cortisol, and dexamethasone suppression tests to screen and diagnose Cushing’s disorders to urine and plasma metanephrines in evaluation for pheochromocytoma. They also offered insights and practical advice for ACTH stimulation testing to diagnose adrenal insufficiency and discussed the challenges of thyroglobulin measurement and interpretation.

Each presenter offered their own unique perspective to the cases. For example, the session kicked off when Don-Wauchope summarized the processes underlying the development of guidelines and highlighted tools evaluating the quality of the guidelines themselves. From a laboratory perspective, he warned that while guidelines are often very good with respect to medications, many are lacking when it comes to laboratory issues such as specifying methods to be used in evaluation, or sometimes even providing cut-off values determined with outdated methods. As illustration, attendees were provided key materials and invited to work together over the lunch break to synergize practice guidelines and key studies to attempt to set a cortisol cutoff concentration for ACTH-stimulation testing. Gilbert provided clinical perspective, describing in vivid detail the presentation of patients with various endocrine afflictions—and noting that they often don’t match the textbooks. Kroner and Shaw brought their unique perspectives as clinical laboratory directors, where they highlighted issues with deriving reference intervals for analytes, such as cortisol that has diurnal variation; testing analytes with limited stability, such as ACTH; and identifying lot-to-lot variation of immunoassays. The speakers also discussed the influence of non-harmonized methods and the impact this has on the interpretation of results. Gilbert lent his perspective as a practicing endocrinologist. He emphasized how critical laboratory testing is to the diagnosis of endocrine diseases, and how important collaboration with the testing laboratory influences the accuracy of a particular diagnosis, as well as contributes to the positive, long-term management of patients. Together they tackled the common challenge of assisting in thyroid function testing interpretation, as well as troubleshooting assay interferences and other sources of discrepant results. Attendees of this session left with a greater appreciation for the testing challenges lurking both in the laboratory and beneath the surface of endocrine practice guidelines, but they also took home solid practices and concepts that can improve laboratory practices and assist physicians with the interpretation of these often complex results.