Viscosity

Serum

1 mL

0.5 mL (Note: This volume does not allow for repeat testing.)

Red-top tube or gel-barrier tube

Evaluate hyperviscosity syndrome associated with monoclonal gammopathy states (myeloma, macroglobulinemia of Waldenström, and other dysproteinemias), including occasional cases of rheumatoid arthritis, SLE, systemic lupus erythematosus, hyperfibrinogenemia

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the Food and Drug Administration.

Viscometry

• 0 to 5 years: Not established

• 6 to 50 years: 1.4−2.0 relative to saline

• >50 years: 1.4−2.1 relative to saline

Values >2.7 may indicate paraproteinemia is present.

Hyperviscosity most frequent (33% of cases)¹ with IgM monoclonal gammopathy (Waldenström macroglobulinemia); next with IgA myeloma. When IgG myeloma leads to hyperviscosity, IgG levels are usually very significantly elevated. A relative viscosity of 6−7 usually results in symptoms of the hyperviscosity syndrome, they have however been described with lower levels of relative viscosity (ie, 4).² Neonatal hyperviscosity, usually but not always associated with polycythemia, may be accompanied by a fairly typical clinical picture. Plethora, hypoglycemia, lethargy, and jitteriness/seizures (CNS symptoms) occur. There may be symptoms and findings suggesting congenital heart disease (CHD) (ie, respiratory distress, cardiac enlargement, and cyanosis). False diagnoses of CHD have been made in such cases. About 50% of such infants have modest hyperbilirubinemia (bilirubin >12 mg/dL).