The rise in concentration of these 2 proteins produces a reciprocal rise in plasma viscosity over the resting state.

To prevent blood loss fibrinogen levels are increased and to combat infection immunoglobulin levels rise. Injury to the body can lead to blood loss and infection, therefore the body prepares itself by increasing the circulating levels of proteins to combat these insults. When the human body is subjected to physiological stress it prepares itself to fight or flee. Untreated myeloma frequently has PV values of >3mPa while plasma containing macroglobulins can have values greater than 10mPa Conditions that secrete paraproteins e.g Myeloma or Macroglobulinaemia are associated with a very high PV. rheumatoid disease, the increased immunoglobulins, along with the inflammatory response, produce a raised plasma viscosity. In infection the initial response is followed by an increase in immunoglobulin which will maintain a high plasma viscosity. Fibrinogen responds as an acute phase reactant and is raised in the initial stages of any inflammatory response. The major influence on Plasma Viscosity is exerted by fibrinogen and immunoglobulins. Values from normal subjects are within a narrowly defined range and are unaffected by physiological stimuli. Therefore, a meaningful blood viscosity test requires more than one measurement: systolic blood viscosity (high shear rate), which is affected by hematocrit, and plasma viscosity and diastolic viscosity (low shear rate), which is affected by several factors like stickiness of platelets, immune complexes that increase the aggregation of RBCs, triglycerides, cholesterol, and many more.Plasma Viscosity (PV) estimation is a non-specific test reflecting changes in plasma proteins. The blood viscosity rises and falls from one extreme to the other with every cardiac cycle, comparable to blood pressure. Its viscosity changes with the applied shear stress. While serum or plasma viscosity measurements play an important role in the clinical management of patients prone to hyper-viscosity syndrome, these tests do not account for hematocrit, blood cell deformability or factors increasing RBC (red blood cell) aggregation. Elevated blood viscosity is a strong independent predictor of cardiovascular events. Blood viscosity is correlated with all known risk factors for cardiovascular diseases. It determines how much friction the blood causes against the vessels, how hard the heart has to work to pump the blood through the body, and how much oxygen is delivered to organs and tissue. The viscosity of blood is a direct measure of the ability of blood to flow through arteries and veins.

Lab test for blood viscosity