Interpreting tests and investigations

Chapters

[00:02] Introduction of Speaker
[00:47] Introduction & Case Study Start
[03:00] Initial Hematology Workup & Blood Film
[05:39] Bone Marrow Biopsy & Plasma Cell Morphology
[07:30] Protein Studies: Serum Protein Electrophoresis (SPEP)
[09:11] Typing the Paraprotein: Immunofixation
[11:26] Serum Free Light Chain (SFLC) Analysis
[14:05] Imaging for Bone Disease
[15:44] Summary of Diagnostic Investigations
[16:41] When Are These Tests Used?
[17:19] Q&A: What is MRD Negative?

Transcript

[0:02] Emma: I will now introduce our second speaker who will be presenting on interpreting tests and investigations, a topic that is very useful in helping you to understand your results of your blood tests and scans and their role in diagnosing and monitoring myeloma. We have with us today Dr. Deepthi Talika, who is a clinical and laboratory hematologist at Canberra Hospital with a clinical and research interest in lymphoma and myeloma. She is an associate professor at the Australian National University, sits on the medical and scientific advisory group of Myeloma Australia, and has published several myeloma guidelines. Welcome Deepthi.

[0:47] Dr. Deepthi Talika: Thank you very much, Emma. Well, thank you for having me, Myeloma Australia, and welcome to everyone. I have been tasked today with telling you about some of the investigations that are performed for both diagnosis and monitoring of multiple myeloma.

I thought I would start with a case, as I find that a really good way to illustrate how patients are managed. Mrs. M.M. is a 72-year-old lady who presents to her GP for routine bloods. She has no symptoms at all. Her ESR (an inflammatory marker) is elevated, and a liver function test shows an increase in globulins. The GP, knowing elevated globulins can indicate myeloma, orders serum immunoglobulins. Her total IgG level is high. The lab suggests additional protein studies and referral to a hematologist.

[3:00] Mrs. M.M. sees a hematologist who requests a range of investigations. A full blood count shows a low hemoglobin (anemia), which is one of the CRAB features (hypercalcemia, renal failure, anemia, bony disease). Looking at her blood film under the microscope, the red cells are stacked on top of each other—a phenomenon called “rouleaux”—caused by high protein in the blood, which is common in myeloma. We can also sometimes see a blue tinge on the slide from the high protein, and very rarely, a plasma cell might be visible in the blood.

A basic biochemistry test shows her calcium is normal, but she has some renal dysfunction (high creatinine, low eGFR). However, Mrs. M.M. also has diabetes, so not all features are necessarily due to myeloma. Hematologists must put the puzzle together by combining investigations.

[5:39] The specific investigations that help make a diagnosis include a bone marrow biopsy. In her biopsy, we see lots of plasma cells. Normally, we have less than 5% plasma cells in the bone marrow; in smouldering or active myeloma, there are at least 10%. Under the microscope, malignant plasma cells have characteristic features: an eccentric (off-center) nucleus, very blue cytoplasm, and a clearing around the nucleus. We also look for immature features, like nucleoli or cells with two nuclei, to confirm they are malignant.

[7:30] Besides the bone marrow, protein studies are key. We already knew she had high globulins and high IgG. To find the abnormal protein, we perform a serum protein electrophoresis (SPEP). In this test, the patient’s plasma is subjected to an electric charge, and proteins separate based on size and charge. In a healthy person, the gamma globulin region shows a broad smear (polyclonal). In myeloma, we see a dense, dark band—the monoclonal protein or “M-protein”—which appears as a sharp peak. This band is measured and reported in grams per litre.

[9:11] We then need to type the paraprotein. Using a test called immunofixation, we run the patient’s plasma on lanes with antibodies against specific proteins (IgG, IgA, IgM, kappa, lambda). In Mrs. M.M.’s case, it showed up clearly as an IgG lambda paraprotein. This is how we know the exact type.

[11:26] So far, we’ve looked at the intact immunoglobulin. Patients also secrete free light chains (the smaller component of the antibody). Measuring serum free light chains is more sensitive for assessing disease burden. The test reports kappa chains, lambda chains, and a ratio. In healthy people, kappa and lambda are balanced in low quantities. In kidney failure, both are high but balanced. In myeloma, there’s a predominance of one type (e.g., high kappa in kappa myeloma). This test is crucial for diagnosing light-chain-only myeloma and for measuring deep responses like stringent complete response (when both the intact protein and the light chains normalise).

[14:05] The final key investigation is for bony disease. Myeloma causes lytic lesions. Previously, we used skeletal surveys with X-rays. Now, we use more sensitive methods like whole-body low-dose CT scans, which are widely available in Australia. MRI and PET-CT scans can be even more sensitive but are less commonly used due to availability and reimbursement.

[15:44] To summarise, for diagnosis we do:

• Blood Tests: Full blood count, renal/liver function, calcium.
• Specific Protein Tests: Serum immunoglobulins, serum electrophoresis (SPEP) to find the M-protein, immunofixation to type it, and serum free light chains.
• Bone Marrow Biopsy
• Scans for bone disease (e.g., whole-body CT).

[16:41] A full workup is done at diagnosis. For monitoring, blood tests (especially protein studies) are typically done every 3-6 months. There’s usually no benefit to testing more frequently than this. If relapse is suspected, a full workup is repeated.

[17:19] Emma: Thank you. We have a question from George: “I have heard the term MRD negative. What does this mean?”
Dr. Talika: Minimal Residual Disease (MRD) is becoming very important in myeloma evaluation. It means that even when standard tests show no disease, we use very sensitive methods (like advanced flow cytometry or next-generation sequencing on bone marrow) to look for tiny amounts of leftover myeloma cells. Achieving MRD negativity after treatment means a patient has had a very deep response, and we expect them to have a longer period before the disease recurs compared to someone who is MRD positive.

Emma: Thank you again, Deepthi, for joining us today and sharing your knowledge.