LOINC Code 68974-5: IgG.intrathecally synthesized/Total IgG (CSF) [Mass fraction]

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.intrathecally synthesized/IgG.total. It is commonly used with the system or sample type 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.intrathecally synthesized/IgG.total in Cerebral spinal fluid
• IgG.intrathecally synthesized/IgG.total
• Note that both the numerator and denominator are concentration of the same protein in the CSF, ..BUT the denominator is the total CSF concentration and the numerator is the contribution of the protein in the CSF that is MADE IN THE CSF (i.e. "intrathecally") ---as opposed to protein that has diffused in from the blood. The calculation is IgX(Intracthecal fraction) = [IgX(Intrathecally synthsized concentration)/IgX(Total CSF Concentration)]*100 from "Multiple Sclerosis (1998) 4, 111 - 117" From the same paper, the "IgX(Intrathecally synthsized concentration)" is complex to determine, but is based on the amount of protein in the CSF over and above that of the normal upper limit expected in the CSF (compared to that in blood). That 'over and above' amount is what is deemed to be produced in the CSF, which is the "Intrathecal Fraction"...... Same theme repeats in other papers (e.g. Am. J. Trop. Med. Hyg., 82(6), 2010, pp. 1094-1098)
• Cerebral spinal fluid; Cerebrospinal Fl; Chemistry; IgG intrathecally produced; IgG.intrathecal; IgG.IT; Immune globulin G; Immunoglobulin G; Mass fraction; Percent; Point in time; QNT; Quan; Quant; Quantitative; Random; Spinal Fl; Spinal Fld; Spinal Flu; Spinal Fluid; Tot; Totl

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

Frequently asked questions