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Test Code SVISC / SVISC-M Viscosity, Serum

Specimen Required

Collection Container/Tube: Red top (serum gel/SST are not acceptable)

Submission Container/Tube: Plastic vial

Specimen Volume: 3 mL

Collection Instructions:

1. Keep specimen at 37° C (eg, 37° C Thermopak, heat block) until after centrifugation.

2. Centrifuge and aliquot serum into plastic vial.

Secondary ID


Useful For

Detection of increased viscosity


Monitoring patients with hyperviscosity syndrome


This test is not useful for patients with small concentrations of monoclonal proteins.

Method Name

Capillary Measurement

Reporting Name

Viscosity, S

Specimen Type

Serum Red

Specimen Minimum Volume

0.75 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

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 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.

Reference Values

≤1.5 centipoises


Failure to follow specimen handling instructions may cause false-low results.


Hyperviscosity syndrome may not be present even if the viscosity is greater than 3 centipoises.

Method Description

The Benson BV200 automated viscometer employs vacuum pressure through a capillary to measure the dynamic viscosity of serum samples. Samples at ambient temperature are aspirated by the sample probe, which is heated to 37° C. Viscosity results are calculated by the instrument at both 25° C and 37° C temperature points. Viscosity units on board the instrument are mPa.s (milli-pascal seconds), which is the International Standard (SI) unit for viscosity. Centipoise (cP) units are named after French physicist Jean Leonard Marie Poiseuille and are used in the centimeter-gram-second (CGS) system of units. 1 mPa.s is equal to 1 cP.(Instruction manual: BV200 Automated Clinical Viscometer User Manual. Benson Viscometers; Ver. 1.5, 02/2020)

Day(s) Performed

Monday through Friday

Report Available

2 to 4 days
NorDx Test Catalog Note:

Analytic time for send out tests is the time it will take to perform testing once it has arrived at the performing reference lab. Please add 1 to 2 days from time of collection to allow for receipt at NorDx central lab and shipment of specimen, add another day if specimen is collected on the day before a weekend or holiday.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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 US Food and Drug Administration.

CPT Code Information


LOINC Code Information

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


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


If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Benign Hematology Test Request Form (T755)

-Hematopathology/Cytogenetics Test Request (T726)