Serum or plasma mass concentration of pneumococcal polysaccharide (e.g., capsular polysaccharide from *Streptococcus pneumoniae*)

Why This Test Might Be Ordered

Your healthcare provider may order this test if you have concerns about immune function, especially after receiving a pneumococcal vaccine, or if you’re at higher risk for pneumococcal infections (e.g., due to weakened immunity, chronic conditions, or recent illness). It may also be used to monitor immune response in certain clinical settings.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, typically drawn from a vein in your arm. The sample is then processed to measure the polysaccharide concentration.

What the Results Mean

Results are qualitative (present/absent) or quantitative (mass concentration in units like mg/L), depending on the method. Higher levels may indicate recent infection or vaccination response, while low or absent levels may suggest immune deficiency or inadequate response.

Common Reasons for Testing

This test is less commonly performed in routine clinical practice but may be used in specialized settings like research, vaccine trials, or patients with suspected immune disorders linked to pneumococcal exposure.