Although some patients with multiple myeloma have no symptoms at all, here are the most common symptoms:
Normally, two major kinds of bone cells work together to keep bones healthy and strong: osteoblasts- cells that lay down new bone; and osteoclasts- cells that break down old bone. Myeloma cells make a substance that tells the osteoclasts to speed up the dissolving of bone. The osteoblasts do not get a signal to put down new bone, so old bone is being broken down without new bone to replace it. This can cause areas of bone weakness that are painful. Any bone can be affected, but back, hip and skull pain is most common. These changes also increase the chance that the bones will break, often from a minor stress or injury.
Low blood counts
When myeloma cells replace normal blood-forming marrow cells, shortages of red blood cells, white blood cells, and blood platelets result. Anemia, when a patient has a reduced number of red blood cells, causes weakness, reduced ability to exercise, shortness of breath, and dizziness. Leukopenia, when there are too few white cells, lowers resistance to infections and can cause such ailments as pneumonia. When blood platelet counts are low (thrombocytopenia), even minor scrapes, cuts, or bruises may cause serious bleeding.
High blood calcium
When myeloma cells dissolve bone, calcium is released, which leads to high blood levels of calcium (hypercalcemia). Symptoms include feeling very thirsty, drinking a lot of fluids, and frequent urination. This can cause dehydration and even kidney failure. High calcium can also cause severe constipation and loss of appetite. It can make patients feel weak, drowsy, and confused. If the level of calcium gets high enough, it can even cause one to lapse into a coma.
Nervous system symptoms
If myeloma weakens the bones in the spine, they can collapse and press on spinal nerves. This can cause sudden severe pain, numbness, and/or muscle weakness. This is a medical emergency and patients should seek medical care immediately.
Sometimes the abnormal proteins produced by myeloma cells can be toxic to the nerves. This damage can lead to weakness and numbness. In some patients, large amounts of myeloma protein can cause the blood to “thicken.” This thickening is called hyperviscosity. and it can slow blood flow to the brain and cause confusion, dizziness, and stroke-like symptoms. Patients with these symptoms should call their doctor immediately. Removing the protein from the blood by a procedure called plasmapheresis can rapidly reverse this problem.
Myeloma protein can damage the kidneys. Initially, it can be asymptomatic but can be found with a blood test. As the kidneys start to fail, they lose the ability to dispose of excess salt, fluid, and body waste products, which can lead to symptoms such as weakness and leg swelling.
Myeloma patients are about 15 times more likely to get infections because the body is unable to make the antibodies that help fight infection. Often, once someone with myeloma gets an infection, it is slow to respond to treatment. That person may stay sick for a long time. Pneumonia is a common and serious infection seen in myeloma patients.
Source: American Cancer Society