How do you utilize serum viscosity in the clinical management of plasma cell disorders?

In brief, I discourage checking serum viscosity in almost all cases.

Why?

1. Hyperviscosity syndrome is a clinical diagnosis. If IgG >7000 mg/dL, IgA > 5000 mg/dL, or IgM > 3000 mg/dL, and the patient has symptoms of hyperviscosity (altered mentation, shortness of breath, tinnitus, mucosal bleeding, e...