The time it takes for a fluid to flow a certain distance is a function of the viscosity of the fluid. Patients with hyperglobulinemia may an increased serum viscosity. This is frequent in macroglobulinemia but may also occur in multiple myeloma if aggregates form or if serum levels are very high.


relative viscosity =

= (flow time of serum) / (flow time of water)



• The flow time of serum is the average of 3 runs of serum through the Ostwald viscometer at 37 C.

• The flow time of water is the average of 3 runs of water through the viscometer.



• The normal relative viscosity is 1.4 to 1.8

• The symptoms of hyperviscosity may begin with a relative viscosity of 4; levels of greater than 6 are usually accompanied by symptoms.


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