LOINCActiveObservation

LOINC Code 2858-9: Protein in CSF/Protein in serum (S+CSF) [Relative ratio]

2858-9 is a LOINC code used to identify Protein in CSF/Protein 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 Protein.CSF/Protein.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 Protein.CSF/Protein.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

Protein in CSF/Protein in serum
Protein.CSF/Protein.serum
Both serum and cerebrospinal fluid; Cerebral spinal fluid; Cerebrospinal Fl; Chemistry; Neuro; Neurology; Point in time; PR; Prot; Prot CSF; Prot CSFSerPl; 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

Protein in CSF/Protein in serum (S+CSF) [Relative ratio]Protein in CSF/Protein in serumProt CSF/SerPlProtein.CSF/Protein.serumCHEMProtein in CSF/Protein in Serum, Serum+Cerebrospinal fluidRelRto

Frequently asked questions

Code details

Code2858-9
SystemLOINC
Display nameProtein in CSF/Protein in serum (S+CSF) [Relative ratio]
DescriptionProtein.CSF/Protein.serum
Short nameProt CSF/SerPl
ComponentProtein.CSF/Protein.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 released1.0
Last changed2.73

Consumer names

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

Part names

Protein.CSF/Protein.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.