Smoldering Myeloma
An intermediate, symptom-free stage between MGUS and active multiple myeloma
Quick Facts
- Type: Plasma cell (blood) disorder
- Stage: Between MGUS and active myeloma
- Symptoms: Usually none
- Main approach: Close monitoring; treatment for high-risk cases
Overview
Smoldering myeloma is an early stage of plasma cell disease that sits between a benign condition called monoclonal gammopathy (MGUS) and active multiple myeloma. Plasma cells are immune cells in the bone marrow that normally make antibodies. In smoldering myeloma, an abnormal group of these cells grows and produces a single type of antibody protein.
What sets smoldering myeloma apart is that the abnormal cells and protein are present at higher levels than in MGUS, but the disease is not yet causing the organ damage that defines active myeloma. People with smoldering myeloma usually feel well and have no symptoms, and the condition is often found through blood tests done for another reason.
Symptoms
By definition, smoldering myeloma does not cause symptoms or organ damage. Most people feel completely well, and the condition is detected on blood or urine tests done for an unrelated reason.
Because there is a chance it can progress to active myeloma, it is important to know the warning signs that would prompt urgent evaluation:
- New or worsening bone pain, especially in the back, ribs, or hips
- Unexplained fractures from minor stress
- Persistent fatigue, weakness, or pallor (signs of anemia)
- Excessive thirst, frequent urination, confusion, or constipation (signs of high calcium)
- Frequent infections or foamy urine
These features may signal a shift from smoldering to active myeloma and should be reported promptly.
Causes
Smoldering myeloma develops when a clone of plasma cells in the bone marrow acquires genetic changes that cause it to grow more than normal and produce abnormal antibody protein. The precise reason these changes occur is not known.
It typically evolves from MGUS and can, over time, progress to active multiple myeloma. The condition is not inherited in a simple way and is not caused by anything a person did. It is more a stage on a biological continuum than a separate disease with a single cause.
Risk Factors
- Older age (risk rises after age 50)
- A prior diagnosis of MGUS
- Higher levels of abnormal protein or plasma cells, which increase the chance of progression
- Certain genetic features of the plasma cells identified on testing
- Family history of plasma cell disorders in some cases
Diagnosis
Smoldering myeloma is diagnosed using specific thresholds that separate it from MGUS and from active myeloma:
- Blood and urine tests: Measuring the abnormal monoclonal protein and free light chains.
- Bone marrow biopsy: To measure the percentage of plasma cells in the marrow.
- Imaging: X-rays, MRI, or PET-CT to confirm there are no bone lesions.
- Organ-function tests: Checking calcium, kidney function, and blood counts to confirm the absence of myeloma-related damage.
The diagnosis rests on having enough abnormal protein or plasma cells to be beyond MGUS, but without the organ damage that defines active myeloma.
Treatment
For most people with smoldering myeloma, the standard approach is careful observation rather than immediate treatment, because many never progress and treatment carries its own risks.
- Active monitoring: Regular blood tests, urine tests, and clinical review, often every few months at first.
- Risk assessment: Doctors estimate how likely the disease is to progress based on protein levels, plasma cell percentage, and genetics.
- Early treatment for high-risk disease: People at high risk of rapid progression may be offered therapy or a clinical trial to delay the onset of active myeloma.
- Bone and general health support: Maintaining vitamin D, staying active, and managing other health conditions.
Living With Smoldering Myeloma
- Keep all scheduled monitoring appointments, as early detection of progression improves outcomes
- Report new bone pain, fatigue, or frequent infections without delay
- Stay physically active to support bone and overall health
- Ask your care team whether a clinical trial is appropriate if you are considered high risk
- Maintain up-to-date vaccinations as advised by your doctor
When to See a Doctor
If you have been told you have smoldering myeloma, contact your care team promptly if you develop new bone pain, unexplained fractures, ongoing fatigue, frequent infections, or symptoms of high calcium such as excessive thirst, confusion, or constipation.
Seek urgent care for sudden severe bone pain, signs of a possible fracture, or significant new weakness, as these may indicate progression to active myeloma that needs prompt treatment.
Frequently Asked Questions
Is smoldering myeloma cancer?
Smoldering myeloma is a precancerous plasma cell condition. It is not active cancer because it is not causing organ damage, but it carries a higher risk of progressing to multiple myeloma than MGUS does, which is why it is monitored closely.
Will smoldering myeloma always turn into multiple myeloma?
No. Some people progress to active myeloma while others remain stable for many years. The likelihood depends on factors such as the amount of abnormal protein, the percentage of plasma cells in the marrow, and genetic features, which doctors use to estimate individual risk.
Why is treatment often delayed?
For people at standard risk, treatment is usually held because many never progress, and starting therapy too early exposes them to side effects without clear benefit. Active monitoring lets doctors begin treatment promptly if signs of progression appear.
How often do I need check-ups?
Monitoring is often every few months at first, then spaced out if the condition stays stable. Your doctor will tailor the schedule to your individual risk level and test results.
What symptoms should make me call my doctor?
Contact your care team for new bone pain, unexplained fractures, ongoing fatigue, frequent infections, or signs of high calcium such as excessive thirst, confusion, or constipation. These can indicate a change toward active myeloma.
References
- National Cancer Institute (NCI). Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment.
- Mayo Clinic. Multiple myeloma.
- Leukemia & Lymphoma Society. Myeloma.
- MedlinePlus, U.S. National Library of Medicine. Multiple myeloma.