79406-5

LOINC code 79406-5 identifies "IgM clearance/Albumin clearance [Ratio] in Serum and CSF". CSF IgM, IgA, and IgG indexes are indicators of intrathecal immunoglobulin synthesis. The calculations incorporate the CSF-serum albumin quotient, an indicator of blood-brain-barrier (BBB) function, in order to differentiate whether the immunoglobulins found in the CSF were produced intrathecally or leaked across the BBB. These immunoglobulin indexes can be useful in the diagnosis of central nervous system infections, neoplasms and primary neurologic diseases such as multiple sclerosis. They also have the potential to monitor treatment efficacy in conditions such as systemic lupus erythematosus with CNS involvement, in which one study found that all three indexes decreased significantly along with CNS symptoms during successful treatment. The CSF IgM index is calculated as (CSF IgM/serum IgM)/(CSF albumin/serum albumin), which can also be represented as (CSF IgM x serum albumin)/(serum IgM x CSF albumin). [PMID: 3899036]

This code measures IgM clearance/Albumin clearance in Ser+CSF. It belongs to the CHEM class in the LOINC classification.

LOINC (Logical Observation Identifiers Names and Codes) is a universal standard for identifying laboratory and clinical observations. It is maintained by the Regenstrief Institute and used worldwide for health data exchange.