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Test ID: VISCS Viscosity, Serum

Reporting Name

Viscosity, S

Useful For

Detection of increased viscosity


Monitoring patients with hyperviscosity syndrome

Specimen Type

Serum Red

Specimen Required

Container/Tube: Red top

Specimen Volume: 1.5 mL

Collection Instructions: Keep specimen at 37° C (eg, 37° C Thermopak, heat block) until after centrifugation and separation of cells.

Specimen Minimum Volume

0.65 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  14 days

Reference Values

≥16 years: ≤1.5 centipoises

Reference values have not been established for patients that are <16 years of age.

Day(s) and Time(s) Performed

Monday through Friday; 3 p.m.

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
VISCS Viscosity, S 3128-6


Result ID Test Result Name Result LOINC Value
8168 Viscosity, S 3128-6

Clinical Information

Viscosity is the property of fluids to resist flow. Hyperviscosity may be manifested by nasal bleeding, blurred vision, headaches, dizziness, nystagmus, deafness, diplopia, ataxia, paresthesias, or congestive heart failure. Funduscopic examination reveals dilation of retinal veins and flame shaped retinal hemorrhages.


The most common cause of serum hyperviscosity is the presence of large concentrations of IgM monoclonal proteins, and Waldenstrom's macroglobulinemia accounts for 80% to 90% of hyperviscosity cases. Hyperviscosity syndrome can also occur in multiple myeloma patients.


Because the ability of a monoclonal protein to cause hyperviscosity is affected by its concentration, molecular weight, and aggregation, sera with concentrations of monoclonal IgM greater than 4 g/dL, IgA greater than 5 g/dL, or IgG greater than 6 g/dL should be tested for hyperviscosity.


Serum viscosity and electrophoresis are recommended before and after plasmapheresis in order to correlate viscosity and M-spike with patient symptoms. This correlation may be useful for anticipating the need for repeat plasmapheresis.


Although viscosities greater than 1.5 centipoises (cP) are abnormal, hyperviscosity is rarely present unless the viscosity is greater than 3 cP.

Clinical Reference

Gertz MA, Kyle RA: Hyperviscosity syndrome. J Intensive Care Med. 1995;10:128-141

Analytic Time

Same day/1 day

Method Name

Sonoclot Coagulation Analyzer


If not ordering electronically, complete, print, and send the following form with the specimen:

--Hematopathology/Cytogenetics Test Request Form (T726)

--Benign Hematology Test Request Form (T755)

Mayo Clinic Laboratories | Hematology Catalog Additional Information:

mml-benign-hematology-disorders, mml-lymphoid-disorders, mml-myeloma-amyloidosis-dysprotenemia