SERUM AND BLOOD VISCOSITY

CLINICAL UTILITY:

The primary purpose of measuring serum viscosity is to diagnose hyperviscosity syndrome, a condition in which the viscosity of serum reaches very high levels, resulting in low perfusion of vital organs and high risk of thrombosis. Since severs hyperviscosity is considered a medical emergency, the test for serum viscosity can be an important tool in evaluating patients with Waldenstrom's macroglobulinemia, multiple myeloma and cryoglobulinemia.

In normal individuals, whole blood viscosity is affected more by the formed elements of the blood than by the serum proteins. However, in diseases with elevated levels of immunoglobulins, particularly IgM, serum viscosity can reach very high levels. In myelomas or immune complex diseases the paraproteins can aggregate or polymerize, resulting in hyperviscosity.

METHOD DESCRIPTION:

Serum viscosity is measured relative to water, using a semiautomated viscoelaastometer in the Coagulation Division.

REFERENCE RANGE:

Ratio of werum to water = 1.4 – 1.9 at room temperature, with a tendency for lower values at 37°C. (Also reported in units of centipoise.)

SPECIMEN REQUIREMENTS:

1.0 mL serum, plasma or whole blood, handled as a cryoglobulin. (Draw one 10 mL red top tube and let clot at 37°C. Send to the lab for separation of serum.) Plasma (drawn in EDTA or heparin tube) and whole blood viscosity are also available.