LOINCActiveObservation

LOINC Code 42207-1: IgG in CSF/IgG in serum (S+CSF) [Relative ratio]

42207-1 is a LOINC code used to identify IgG in CSF/IgG in serum (S+CSF) [Relative ratio] in laboratory and clinical observation data. You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges. LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component IgG.CSF/IgG.serum. It is commonly used with the system or sample type Ser+CSF.

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

LOINC codes identify tests, measurements, observations, survey items, and clinical questions in a standardized way. It is associated with the component IgG.CSF/IgG.serum. It is commonly used with the system or sample type Ser+CSF.

When is it used?

  • Used in lab systems, EHRs, and clinical data exchange.
  • May identify a test, observation, survey item, or clinical document request rather than a diagnosis.
  • Status: ACTIVE
  • Order vs observation: Observation

What it does not mean

  • The code identifies the observation or test, not the actual result.

Key facts

  • IgG in CSF/IgG in serum
  • IgG.CSF/IgG.serum
  • Both serum and cerebrospinal fluid; Cerebral spinal fluid; Cerebrospinal Fl; Chemistry; IgG CSF; Immune globulin G; Immunoglobulin G; Point in time; QNT; Quan; Quant; Quantitative; Random; Relative ratio; Ser; SerPl; Serum; Spinal Fl; Spinal Fld; Spinal Flu; Spinal Fluid; SR

Where you may see this code

You may see this code in lab systems, lab reports, EHR exports, interoperability feeds, or other structured clinical data exchanges.

Common synonyms

IgG in CSF/IgG in serum (S+CSF) [Relative ratio]IgG in CSF/IgG in serumIgG CSF/SerPlIgG.CSF/IgG.serumCHEMIgG in CSF/IgG in Serum, Serum+Cerebrospinal fluidRelRto

Frequently asked questions

Code details

Code42207-1
SystemLOINC
Display nameIgG in CSF/IgG in serum (S+CSF) [Relative ratio]
DescriptionIgG.CSF/IgG.serum
Short nameIgG CSF/SerPl
ComponentIgG.CSF/IgG.serum
PropertyRelRto
TimingPt
System (specimen)Ser+CSF
ScaleQn
ClassCHEM
Example unitsRatio
StatusACTIVE
Order/ObservationObservation

Flags

BillableNo
Valid clinical useNo

Source

SourceLOINC
Version2.82
Releasemain
First released2.16
Last changed2.73

Consumer names

IgG in CSF/IgG in Serum, Serum+Cerebrospinal fluid

Part names

IgG.CSF/IgG.serumRelRtoPtSer+CSFQnRelative RatioPoint in time (spot)Serum and CSF

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from LOINC. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.