The Cryoglobulins test detects abnormal immunoglobulin proteins (cryoglobulins) in the blood that precipitate at low temperatures (below 37°C) and dissolve at body temperature. This test is typically ordered when cryoglobulinemia is suspected—an inflammatory condition associated with symptoms like skin rash (purpura), joint pain, renal impairment, or neuropathy. Cryoglobulins are often linked to underlying diseases such as infections (e.g., hepatitis C), autoimmune disorders (e.g., lupus or Sjögren’s syndrome), or lymphomas. Blood samples must be collected and transported to the laboratory at body temperature to prevent cryoglobulin dissolution. A positive result helps identify the cryoglobulin type (I, II, or III), guiding the diagnosis of the underlying cause and treatment strategy. Results require correlation with clinical symptoms, supplementary tests (e.g., rheumatoid factor or hepatitis C serology), and exclusion of non-specific factors, as improper sample collection or storage may cause false-positive results.