Binding Site Blog
The Significance of CRAB (Multiple Myeloma)
What does astrology have to do with Multiple Myeloma? More than you might think.
Cancer is the fourth sign of the zodiac spanning June 22
to July 22. The Crab is the mascot of the Cancer zodiac sign. The
letters C-R-A-B also stand for four clinical manifestations of Multiple
Myeloma, a cancer of the blood resulting from the proliferation of
malignant plasma cells. The presence of CRAB criteria are important
diagnostic indicators of Multiple Myeloma. In 2003, the International
Myeloma Working Group (IMWG) defined the CRAB criteria in the British
Journal of Hematology(1).
C stands for Calcium. Patients with Multiple
Myeloma can have elevated levels of calcium (hypercalcemia) due to the
breakdown of bone. Hypercalcemia resulting from Multiple Myeloma must be
differentiated from other causes such as overactivity of the
parathyroid glands, medications and excessive use of calcium and Vitamin
D supplements.
R stands for Renal. Many patients with Multiple
Myeloma have some degree of renal insufficiency at diagnosis. If
untreated, patients with Multiple Myeloma can progress to a condition
called myeloma kidney and may lose their kidney function completely.
Patients with acute kidney injury (AKI) resulting from Multiple Myeloma
need to be differentiated from those with AKI from other causes to make
sure the correct treatment is initiated.
A stands for Anemia. In Multiple Myeloma,
cancerous plasma cells invade the bone marrow and can disrupt normal
hematopoiesis or blood formation. This results in decreased red blood
cell production and the condition called anemia. Anemic patients often complain of fatigue which is one of the common signs of Multiple Myeloma.
B stands for Bone. Many patients with Multiple Myeloma have bone lesions. These
lesions are caused by the destruction of bone in areas where cancerous
plasma cells have made a niche in the bone marrow. In these areas
malignant plasma cells cause the activation of osteoclasts that in turn,
cause bone resorption and the release of calcium from the bone into the
serum. The bone in these areas may be weakened and fractures are often
an unwanted sequela.
Following routine laboratory evaluations (Freelite® serum
free light chain assays, serum protein electrophoresis, immunofixation
electrophoresis), it is important for clinicians to be able to
differentiate CRAB conditions resulting from Multiple Myeloma from other
causes. Individual CRAB criteria can be associated with many
pathologies and the faster the root cause of symptoms are diagnosed, the
faster the patient will receive appropriate treatment.
