Testing

The diagnosis of mitochondrial disease can be particularly challenging as the presentation can occur at any age, involve virtually any organ system, and be associated with widely varying severities. Due to the considerable overlap in the clinical phenotypes of various mitochondrial disorders, it is often difficult to distinguish these specific inherited disorders without genetic testing.

The current diagnostic tools in a pathologist’s arsenal sometimes cannot provide a clear distinction between primary mediastinal large B-cell lymphoma (one of the few lymphomas more common in younger women) and diffuse large B-cell lymphoma, the most common type of non-Hodgkin’s lymphoma overall.

Joshua Bornhorst, Ph.D., gives an overview of the new Copeptin test available through Mayo Clinic Laboratories. He discusses when this testing should be ordered, how this testing improves upon previous testing approaches, and what clinical action can be taken due to the results of this testing.

Jeffrey (Jeff) Meeusen, Ph.D., gives an overview of the new nuclear magnetic resonance (NMR) lipoprotein profile available through Mayo Clinic Laboratories. He discusses when this testing should be ordered, how this testing improves upon previous testing approaches, and what clinical action can be taken due to the results of this testing.

Nikola Baumann, Ph.D., gives an overview of the new NASH-FibroTest available through Mayo Clinic Laboratories. She discusses when this testing should be ordered, how this testing improves upon previous testing approaches, and what clinical action can be taken due to the results of this testing.

Autoimmune neurological disorders can often be treated, sometimes with full restoration of function. However, because the symptoms mimic other conditions, autoimmune neurological disorders are frequently misdiagnosed, resulting in an irreversible loss of function.

A movement disorder might be caused by the body’s immune system, which is meant to fight infections, suddenly attacking the brain. Fortunately, an “autoimmune movement disorder” can often be treated—once its cause is discovered.

Necrotizing autoimmune myopathy (NAM) is a serious but rare muscle disease strongly associated with autoantibodies to either the protein signal recognition particle (SRP) or the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR). NAM typically manifests with subacute proximal limb muscle weakness and persistently elevated serum creatine kinase (CK) concentrations, but slower onsets can occur and complicate diagnosis.

Chromium and cobalt blood tests are used to monitor exposure to these elements. Both of these elements are naturally occurring and widely distributed in the environment. Previously, serum samples were collected and used to monitor patients with metal-on-metal implants, but serum can easily be contaminated during the harvesting and separation of the serum from the cellular blood components causing incorrect results. By using the new EDTA anticoagulated whole-blood test, which is collected in a trace element tube instead of using serum, the risk of contamination is significantly reduced.

Many patients may have flare-ups of their disease, or they may stop responding to treatment. In these situations, the clinician may choose to increase the dose administered or recommend more frequent injections. One cause of decreased response to treatment is the appearance of anti-drug antibodies or “immunogenicity.”

High-sensitivity troponin T is a new assay recently approved by the U.S. Food and Drug Administration. This assay is most often used to evaluate patients with possible acute ischemic heart disease, but it also has a variety of uses in the more chronic setting.

Ann Moyer, M.D., Ph.D., discusses an additional gene, NUDT15, which is important in the prediction of thiopurine-related toxicity This gene has been added to our TPMT genotyping assay available through Mayo Medical Laboratories.

Devin Oglesbee, Ph.D., Director of the Biochemical and Molecular Genetics Laboratories at Mayo Clinic, provides an overview of the lysosomal storage disease panel, when it is appropriate to order this test, what actions the results allow you to take, and how this test improves upon previous approaches.