Most Common Signs of Multiple Myeloma You Shouldn't Ignore
Multiple myeloma, a type of blood cancer, originates in plasma cells—white blood cells responsible for producing antibodies. In this condition, abnormal plasma cells multiply uncontrollably in the bone marrow, leading to the overproduction of dysfunctional immunoglobulins. This disrupts normal immune function and causes widespread damage to multiple organs. To help identify early warning signs, clinicians often use the mnemonic CRAB, which stands for key clinical features: elevated Calcium levels, Renal (kidney) dysfunction, Anemia, and Bone lesions.
Understanding the CRAB Symptoms of Multiple Myeloma
Elevated Calcium Levels (Hypercalcemia)
The "C" in CRAB refers to hypercalcemia, a condition where calcium levels in the blood rise significantly due to excessive bone breakdown. Patients may experience symptoms such as extreme thirst, frequent urination, constipation, confusion, or even cardiac arrhythmias. Left untreated, high calcium can lead to serious neurological and cardiovascular complications.
Renal (Kidney) Damage
The "R" highlights kidney impairment, one of the most common and serious complications. Abnormal proteins produced by malignant plasma cells—known as M proteins—can accumulate in the kidneys, impairing their ability to filter waste. This often leads to reduced kidney function or even acute renal failure. Many patients are initially diagnosed in nephrology departments after presenting with unexplained proteinuria or declining glomerular filtration rates.
Anemia and Fatigue
"A" stands for anemia, which occurs when cancerous plasma cells crowd out healthy red blood cell production in the bone marrow. As a result, patients frequently feel weak, fatigued, short of breath, and appear pale. Blood tests typically reveal low hemoglobin levels, prompting further investigation into underlying causes.
Bone Pain and Skeletal Damage
The "B" represents bone-related issues, including severe bone pain, osteoporosis, and pathologic fractures. Myeloma cells activate osteoclasts—cells that break down bone—leading to lytic lesions visible on X-rays, especially in the spine, pelvis, and ribs. Patients often report persistent back pain or suffer fractures from minor trauma, sometimes leading them to orthopedic specialists before the true diagnosis is uncovered.
Other Important but Less Recognized Symptoms
Beyond the CRAB criteria, multiple myeloma can present with several other systemic manifestations. Frequent infections are common due to impaired antibody production, leaving patients vulnerable to pneumonia, urinary tract infections, and other illnesses. Some develop hyperviscosity syndrome, where thickened blood from excess proteins causes dizziness, blurred vision, or nosebleeds.
Neurological symptoms such as numbness, tingling in the hands and feet (peripheral neuropathy), or lightheadedness may also occur, either from nerve compression due to bone lesions or as side effects of abnormal protein buildup. Additionally, patients might experience easy bruising or bleeding caused by low platelet counts resulting from bone marrow infiltration.
Why Diagnosis Is Often Delayed
One of the biggest challenges with multiple myeloma is its nonspecific and subtle early symptoms. Because signs like fatigue, back pain, or mild kidney issues mimic more common conditions, patients often seek care in specialties outside hematology—such as nephrology, orthopedics, or primary care. It's not uncommon for individuals to be misdiagnosed with arthritis, osteoporosis, or chronic kidney disease before the correct diagnosis is made.
This diagnostic delay underscores the importance of awareness among both patients and healthcare providers. Anyone experiencing unexplained bone pain, persistent fatigue, recurrent infections, or abnormal lab results—especially elevated calcium or abnormal protein levels—should consider a thorough hematologic evaluation. Early detection improves treatment outcomes and helps prevent irreversible organ damage.