The Silent Intruder: How Multiple Myeloma Can Affect the Body

Multiple myeloma, often simply called myeloma, is a cancer of plasma cells that develops in the bone marrow. Although it begins in one type of blood cell, its effects can reach far beyond the marrow. Bones, kidneys, blood cells, the immune system, nerves, and other organs can all be affected.

That is part of what makes myeloma such a complicated disease. Two people with the same diagnosis may experience it very differently. Some develop significant bone disease, while others first show signs of kidney problems, anemia, frequent infections, or abnormal bloodwork.

Understanding what myeloma can do to the body isn't meant to create fear. It can help patients recognize symptoms, understand why certain tests are performed, and have more informed conversations with their healthcare team.

The Impact on Bones

Bone damage is one of the best-known complications of multiple myeloma.

Normally, our bones are constantly being remodeled. Old bone is broken down by cells called osteoclasts, while new bone is created by osteoblasts. Myeloma can disrupt this carefully balanced process, increasing bone breakdown while interfering with the body's ability to rebuild it.

The result can be lytic lesions—areas where bone has been weakened or destroyed. These lesions commonly occur in the spine, skull, ribs, pelvis, and other bones containing active marrow.

Bone involvement may cause persistent pain, fractures from relatively minor trauma, collapsed vertebrae, loss of height, and mobility problems.

As bone breaks down, calcium may also be released into the bloodstream, causing hypercalcemia. High calcium levels can cause symptoms including excessive thirst, frequent urination, constipation, weakness, confusion, and kidney problems.

Effects on the Kidneys

Kidney problems can sometimes be one of the first clues that something is wrong.

Myeloma cells may produce abnormal immunoglobulins or portions of them called light chains. When excessive amounts of these proteins pass through the kidneys, they can injure the delicate structures responsible for filtering the blood.

Kidney function may also be affected by dehydration, high calcium levels, infections, certain medications, and other complications.

Damage ranges from mild impairment to acute kidney injury or, in severe cases, kidney failure requiring dialysis. Fortunately, kidney function can sometimes improve when myeloma is brought under control and contributing problems are treated quickly.

Blood and the Immune System

Healthy bone marrow is essentially a blood-cell factory. As myeloma cells accumulate, they can crowd out normal blood-forming cells.

One common consequence is anemia, or too few healthy red blood cells. Anemia can contribute to fatigue, weakness, dizziness, shortness of breath, and reduced stamina.

Platelet and white blood cell counts can also become low in some patients, either because of the disease itself or its treatment.

Myeloma creates another unusual problem: although malignant plasma cells may produce large quantities of an abnormal antibody or antibody fragment, production of the normal antibodies needed to fight infection can decrease.

That leaves many people with myeloma particularly vulnerable to infections. Infection prevention, vaccinations when appropriate, prompt evaluation of symptoms, and careful monitoring therefore become important parts of myeloma care.

The Spine and Nervous System

When myeloma weakens the vertebrae, a vertebral compression fracture can occur. In some circumstances, a tumor or damaged vertebra can place pressure on the spinal cord or surrounding nerves.

Symptoms may include severe or worsening back pain, numbness or tingling, weakness in the arms or legs, or difficulty walking.

New loss of bladder or bowel control, significant weakness, or symptoms suggesting spinal cord compression require urgent medical attention. Early treatment can be critical to preventing permanent neurological damage.

Peripheral neuropathy can also occur in people living with myeloma, although it may result from the disease, other medical conditions, or certain myeloma treatments.

The Heart and Cardiovascular System

The relationship between myeloma and cardiovascular disease is more complicated than simply saying that myeloma damages the heart.

Anemia, kidney dysfunction, infections, electrolyte abnormalities, blood clots, and certain cancer treatments can all place additional strain on the cardiovascular system.

Some patients also develop AL amyloidosis, a separate but related plasma-cell disorder in which abnormal light-chain proteins form amyloid deposits in organs. When those deposits involve the heart, they can interfere with its ability to function normally.

Because there are many possible causes of cardiovascular symptoms, new shortness of breath, swelling, chest discomfort, fainting, or persistent heart rhythm changes should be evaluated rather than automatically attributed to myeloma.

The Mouth and Jaw

Oral health deserves special attention during myeloma treatment.

Bone-strengthening medications such as bisphosphonates and denosumab can be extremely valuable for reducing skeletal complications. However, in uncommon cases, they are associated with a serious condition called medication-related osteonecrosis of the jaw (MRONJ).

This does not mean everyone taking these medications will develop jaw problems. The risk is influenced by factors including treatment duration, dental health, and invasive dental procedures.

Ideally, patients should have appropriate dental evaluation before beginning bone-modifying therapy and maintain good oral hygiene and regular dental care afterward. Patients should also make sure their dentist knows about their myeloma medications before extractions or other invasive dental work.

Treatment and Management

There has been tremendous progress in multiple myeloma treatment. Today's options extend well beyond traditional chemotherapy and may include proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, corticosteroids, targeted therapies, autologous stem cell transplantation, CAR-T cell therapy, and bispecific antibodies.

The best approach depends on many factors, including the person's age and overall health, kidney function, disease characteristics, previous treatments, cytogenetic risk, and individual goals.

Supportive care is equally important. Managing pain, protecting bones, preventing and treating infections, maintaining kidney health, treating anemia, and monitoring treatment side effects can make an enormous difference in both health and quality of life.

An autologous stem cell transplant is an important treatment for eligible patients, but it is not currently considered a guaranteed cure for multiple myeloma. It can produce deep and sometimes very long-lasting remissions.

Living With the Silent Intruder

Multiple myeloma may begin in the bone marrow, but its reach can extend throughout the body. That is why myeloma care involves much more than watching a single laboratory number.

Doctors monitor blood counts, kidney function, calcium levels, monoclonal proteins or free light chains, bones, symptoms, and other indicators to build a picture of what the disease is—or isn't—doing.

And while multiple myeloma remains generally considered a treatable but incurable blood cancer, the outlook has changed dramatically. New treatments continue to produce deeper responses and longer remissions, and researchers continue to investigate what long-term disease control—and perhaps one day cure—might look like.

Knowledge gives patients another tool in that fight. Understanding how myeloma can affect the body can make it easier to recognize changes, ask questions, advocate for appropriate care, and participate actively in treatment decisions.

The silent intruder may be complicated, but it doesn't have to remain mysterious.