What plasma cell percentage means myeloma?

Doctors sample the hip marrow to count abnormal plasma cells. A clonal plasma cell level of 10% or higher confirms multiple myeloma. A level of 60% or higher means highly active disease that needs treatment even if you still feel well.

What is the difference between SPEP and immunofixation?

SPEP measures how much M-protein is in the blood, and 10 g/L or more is typically called measurable disease. Immunofixation identifies the exact type of that protein, such as IgG, IgA, kappa, or lambda. Together they tell your team both the amount and the fingerprint of the myeloma protein.

Which free light chain numbers matter?

A healthy kappa-to-lambda ratio is 0.26 to 1.65. An extremely abnormal ratio of 100 or higher, with the involved light chain at 100 mg/L or more, is a major warning sign of active myeloma. This test is especially important when the cancer mainly makes small light-chain fragments.

What does FISH tell my doctor?

FISH uses glowing dyes to read the chromosomes inside myeloma cells. You may see translocations such as t(4;14) or t(14;16), a missing piece such as del(17p), or extra copies such as +1q. Those high-risk changes suggest faster-growing disease and may lead to a stronger treatment plan.

How does ISS staging work?

The International Staging System combines beta-2 microglobulin and albumin. Stage I, the most favorable, is a beta-2 microglobulin below 3.5 mg/L plus albumin of 3.5 g/dL or higher. Stage III is a beta-2 microglobulin of 5.5 mg/L or higher.

Why do I need MRI or PET-CT instead of plain X-rays?

Old X-rays often miss early bone damage. MRI is excellent for marrow and spine, and more than one focal lesion of 5 mm or larger is proof of active myeloma. PET-CT lights up active cancer anywhere in the body, including disease that has grown outside the bones.

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Newly Diagnosed

Understanding Lab Reports

Name: Understanding Lab Reports | CMDN
Creator: CMDN Editorial Team
Published: 2026-07-30

Decoding Bone Marrow, M-protein, FISH, and Scans

Medical Disclaimer: The following content is compiled based on the latest authoritative guidelines at home and abroad. It is for reference only for patients and their families and cannot replace the professional medical advice of the attending physician. Please be sure to follow the doctor's advice for the treatment plan.

Core Conclusion

Deciphering myeloma lab reports centers on 4 key metrics: serum M-protein (g/L), serum free light chain ratio (normal 0.26 to 1.65), bone marrow plasma cell percentage (≥10% threshold), and high-risk FISH markers like del(17p) or 1q gain.

Detailed Points

(1) Bone Marrow Aspiration and Biopsy (Your Blood Cell Factory): Because myeloma is a cancer of the bone marrow, doctors need to look directly inside your bones (usually the hip) using a needle to take a small fluid and tissue sample. They are looking for your plasma cell percentage. Normal plasma cells fight infection, but in myeloma, they grow out of control. If your bone marrow has ≥ 10% clonal (abnormal) plasma cells, it confirms a multiple myeloma diagnosis. If the percentage is ≥ 60%, it indicates highly active disease that requires immediate treatment, even if you do not feel sick yet.
(2) SPEP and Immunofixation (Hunting for the "M-Protein"): Myeloma cells produce a useless, abnormal antibody called a monoclonal protein, or M-protein.
- SPEP (Serum Protein Electrophoresis): This test acts like a scale. It uses an electrical current to separate your blood proteins and measures the exact amount of M-protein present (often called the "M-spike"). A value of ≥ 10 g/L in the serum is typically considered measurable disease.
- Immunofixation (IFE): This test acts like a fingerprint scanner. It identifies the exact type of M-protein your myeloma is producing (such as IgG, IgA, kappa, or lambda).
(3) Serum Free Light Chain (sFLC) Assay (Finding the Fragments): Antibodies are made of "heavy chains" and smaller "light chains". Sometimes, myeloma cells are a bit defective and only pump out the smaller light chains (known as kappa or lambda) into your blood. Normally, your kappa and lambda light chains are perfectly balanced with a ratio between 0.26 to 1.65. An extremely abnormal ratio of ≥ 100 (with the involved light chain being ≥ 100 mg/L) is a major warning sign of active multiple myeloma.
(4) FISH Testing (Reading the Cancer's "Instruction Manual"): FISH (Fluorescence In Situ Hybridization) uses special glowing dyes to look deeply into the chromosomes (DNA) of your myeloma cells. It helps doctors understand the "personality" of your cancer. You might see terms like:
- Translocation: When pieces of different chromosomes break off and illegally swap places with each other (e.g., t(4;14) or t(14;16)).
- Deletion: When a piece of a chromosome is entirely missing (e.g., del(17p)).
- Amplification/Gain: When there are extra copies of a chromosome (e.g., +1q). Having these specific abnormalities means your myeloma is considered "high-risk" and may grow faster, which helps your doctor know that you might need a stronger or more tailored treatment.
(5) Beta-2 Microglobulin and Albumin (ISS Staging): These two simple blood tests are combined to form the International Staging System (ISS), which helps predict your overall prognosis.
- Beta-2 Microglobulin (β2M): This is a protein shed by myeloma cells. Lower is better.
- Albumin: This is a normal protein that reflects your overall health and nutrition. Higher is better. Under the ISS, the most favorable stage (Stage I) is defined as having a β2M level of < 3.5 mg/L and Albumin of ≥ 3.5 g/dL. Conversely, Stage III is defined as having a β2M level of ≥ 5.5 mg/L.
(6) The Role of Imaging (PET-CT / MRI): Myeloma can cause soft spots or "holes" (osteolytic lesions) in your bones. Old-fashioned X-rays are no longer recommended because they often miss early bone damage. Today, doctors rely on highly sensitive advanced scans:
- MRI (Magnetic Resonance Imaging): Outstanding for looking inside the bone marrow and spine. Finding more than one focal lesion that is ≥ 5 mm in size is definitive proof of active myeloma.
- PET-CT: This scan uses a safe radioactive sugar tracer to light up areas of active cancer anywhere in your body, making it incredible for finding myeloma that has grown outside of the bones (extramedullary disease).

The above content is sourced from the following references

Management of relapsed multiple myeloma: A British Society of Haematology and UK Myeloma Society guideline
EHA–EMN Evidence-Based Guidelines for diagnosis, treatment and follow-up of patients with multiple myeloma
NCCN Clinical Practice Guidelines in Oncology: Multiple Myeloma
NCCN Guidelines for Patients® Multiple Myeloma
Singapore Myeloma Study Group consensus guidelines for the management of patients with multiple myeloma
Multiple Myeloma Learn Your Labs
Multiple Myeloma Disease Overview
International Myeloma Society/International Myeloma Working Group Consensus Recommendations on the Definition of High-Risk Multiple Myeloma

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FAQs

What plasma cell percentage means myeloma?: Doctors sample the hip marrow to count abnormal plasma cells. A clonal plasma cell level of 10% or higher confirms multiple myeloma. A level of 60% or higher means highly active disease that needs treatment even if you still feel well.
What is the difference between SPEP and immunofixation?: SPEP measures how much M-protein is in the blood, and 10 g/L or more is typically called measurable disease. Immunofixation identifies the exact type of that protein, such as IgG, IgA, kappa, or lambda. Together they tell your team both the amount and the fingerprint of the myeloma protein.
Which free light chain numbers matter?: A healthy kappa-to-lambda ratio is 0.26 to 1.65. An extremely abnormal ratio of 100 or higher, with the involved light chain at 100 mg/L or more, is a major warning sign of active myeloma. This test is especially important when the cancer mainly makes small light-chain fragments.
What does FISH tell my doctor?: FISH uses glowing dyes to read the chromosomes inside myeloma cells. You may see translocations such as t(4;14) or t(14;16), a missing piece such as del(17p), or extra copies such as +1q. Those high-risk changes suggest faster-growing disease and may lead to a stronger treatment plan.
How does ISS staging work?: The International Staging System combines beta-2 microglobulin and albumin. Stage I, the most favorable, is a beta-2 microglobulin below 3.5 mg/L plus albumin of 3.5 g/dL or higher. Stage III is a beta-2 microglobulin of 5.5 mg/L or higher.
Why do I need MRI or PET-CT instead of plain X-rays?: Old X-rays often miss early bone damage. MRI is excellent for marrow and spine, and more than one focal lesion of 5 mm or larger is proof of active myeloma. PET-CT lights up active cancer anywhere in the body, including disease that has grown outside the bones.

References used for this guide

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for myeloma patients globally

Disclaimer: All disease knowledge, guideline interpretations, and treatment processes provided on this site are for learning and reference only, and do not constitute any medical advice or professional diagnosis. The condition of each patient is unique. For specific treatment plans and medication decisions, please be sure to follow the guidance of your attending physician or professional medical team.

This article is reviewed and published by the CMDN Editorial Team

Last updated: 2026-07-30

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