Citrulline

metabolite

Citrulline reflects arginine bioavailability and nitric oxide synthesis, modulating endothelial activation and vasomotor function.

Pathway placement

Cascade stepEndothelial activation & erosion

Confidencemedium

RationaleL-arginine/NO pathway marker; endothelial function biomarker.

Druggability

Not assessed (no mapped human gene target).

Type I vs Type II discrimination

ScoresLow-confidence (proxy)

R — rupture / Type-I

C — confounder / Type-II

A — assay feasibility

E — evidence strength

T1DI (composite)

Specificity differential (R−C)-31.4

Confounder panel (Type-II drivers)

No confounder evidence retrieved.

Tier: light (literature co-occurrence proxy — lower confidence). See the discrimination table for all markers.

Class-level default (no specific cleared assay)— generic method inferred from analyte class; confirm against a specific product insert before use.

Specimen

Serum, plasma or urine

Collection tube

Serum separator (gold/red-top, SST) · Lithium heparin (green-top) · Sterile urine container

Method / principle

LC-MS/MS (targeted metabolomics) or enzymatic colorimetric where available

Reagent / substrate

Stable-isotope-labeled internal standard (MS); or enzyme-coupled Trinder reagent

Platform

LC-MS/MS; some automated chemistry

Turnaround · availability

Send-out / research · Specialized / research