Determine serum viscosity. Serum viscosity is diagnostic in evaluating hyperviscosity syndrome. The reference range is 1.4-1.8 units. Symptoms usually are not seen before the viscosity reaches 4 units, and hyperviscosity syndrome usually presents with a serum viscosity greater than 5 units. Obtain a peripheral blood smear.
Rouleaux formation is often present with increased serum viscosity.
Tailor additional workup to the patient's presentation. Consider panculture and urinalysis. Multiple myeloma is complicated frequently by infections. In nonneutropenic patients, infections are usually secondary to Streptococcus pneumoniae or Haemophilus influenzae . Search for other disorders.