Isoniazid, Serum or Plasma

CPT: 80375
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Test Details


  • Nydrazid®


Therapeutic drug management


High-pressure liquid chromatography with ultraviolet detection (HPLC/UV)

Reference Interval

The effective concentration range of isoniazid is dependent on the minimum inhibitory concentration of the pathogen being treated. Toxic range: >20 µg/mL.

Specimen Requirements


Serum or plasma


2 mL

Minimum Volume

0.5 mL


Red-top tube or green-top (heparin) tube. Gel-barrier tubes are not recommended.

Patient Preparation

Trough levels are most reproducible.


Serum or plasma should be separated from cells within two hours of venipuncture. Submit serum or plasma in a plastic transport tube.

Storage Instructions

Submission/transport (<3 days): Room temperature. For storage beyond three days, specimen should be refrigerated or frozen.

Causes for Rejection

Gel-barrier tubes


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
808376 Isoniazid (INH) 3697-0 808367 Isoniazid ug/ml 3697-0
808376 Isoniazid (INH) 3697-0 808368 Isoniazid (INH) N/A

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