Normal Range for Cyanide (C2) Levels
I cannot provide a definitive normal range for "Cya C2" levels because this terminology does not appear in standard medical literature or the provided evidence, and no established reference ranges are documented in the guidelines reviewed.
What the Evidence Shows
The available toxicology literature does not define a "normal range" for cyanide levels in the conventional sense, as cyanide is a toxic substance rather than a physiologic marker with homeostatic regulation 1, 2.
Diagnostic Thresholds in Poisoning
The evidence provides context for toxic cyanide levels rather than normal ranges:
- Whole blood cyanide level of 13 micrograms/mL was documented in a severe poisoning case requiring antidote treatment 3
- Plasma lactate concentration ≥10 mmol/L in fire victims (without severe burns) or ≥8 mmol/L in pure cyanide poisoning serves as a sensitive and specific indicator of cyanide intoxication 2
- These lactate thresholds are used clinically because direct cyanide measurement is often not rapidly available 2
Biomonitoring for Chronic Exposure
For chronic low-level exposure monitoring (not acute poisoning):
- Thiocyanate (SCN-) in urine or plasma serves as the practical biomarker for cyanide exposure 4
- Biomonitoring Equivalent (BE) values range from 0.0008 to 0.8 mg/L for urinary SCN- and 0.0005 to 2.5 mg/L for plasma SCN-, corresponding to various reference exposure levels 4
- However, these values have significant limitations due to biomarker specificity issues and uncertainty in background levels 4
Clinical Implications
In practice, cyanide toxicity is diagnosed clinically rather than by laboratory reference ranges 1, 2. Key clinical features include:
- Rapid onset of symptoms (within 1 minute of inhalation or minutes of ingestion) 5
- Metabolic acidosis with elevated lactate 2
- Cardiovascular collapse and altered mental status 1, 5
Treatment should never be delayed waiting for cyanide level results when clinical suspicion is high 1, 2. Hydroxocobalamin is recommended as first-line antidote therapy for suspected cyanide poisoning 1, 6.
Important Caveat
If you are referring to a specific laboratory test with the designation "Cya C2," you should consult your laboratory's specific reference ranges, as this may be an institution-specific or assay-specific nomenclature not found in standard medical literature.