Table 1.

Causes of a high or low calculated globulin

High calculated globulin levels	Low calculated globulin levels
Plasma cell dyscrasias and lymphoproliferative disease, e.g. myeloma, Waldenstrom's macroglobulinaemia	Primary antibody deficiency, e.g. CVID
Monoclonal gammopathy of undetermined significance (MGUS)	Small paraproteins with immune-paresis
Viral infections, e.g. HIV, EBV, HBV	Secondary antibody deficiency, e.g. lymphoma, chemotherapy, rituximab, protein losing enteropathy, plasma exchange, renal losses (e.g. nephrotic syndrome) and immunosuppressive drugs
Sarcoidosis	Fluid therapy/shifts, e.g. peri-operatively or in acutely unwell patients such as ITU or medical therapy involving fluid resuscitation
Connective tissue disease, e.g. systemic lupus erythematosus, Sjögrens syndrome, rheumatoid arthritis
Autoimmune hepatitis, primary biliary sclerosis, primary sclerosing cholangitis
Chronic infection, e.g. TB, osteomyelitis, endocarditis, hepatitis

EBV = Epstein–Barr virus; HBC = hepatitis B core antigen; CVID = common variable immunodeficiency; TB = tuberculosis; ITU = intensive care unit.