Summary & Overview
CPT 83921: Single Organic Acid Analyte Measurement
CPT code 83921 identifies a laboratory assay that measures a single organic acid analyte from biological specimens such as serum, plasma, urine, amniotic fluid, or blood spot. This code is used for targeted organic acid testing when clinicians order measurement of one specific metabolite among more than 60 known organic acids. Nationally, single-analyte organic acid testing matters for metabolic diagnostics, toxicology screens, and targeted monitoring in clinical genetics, neonatology, and metabolic disease management.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context and service settings, standard billing considerations, and typical sites of service. The publication outlines common use cases for single-analyte organic acid testing, discusses payer coverage patterns at a high level, and highlights operational considerations for ordering and specimen handling. Data not available in the input is noted where applicable.
This summary provides clinicians, laboratory directors, and billing staff with a concise reference to the purpose and application of CPT code 83921, the clinical scenarios in which it is ordered, and the principal payers implicated in coverage decisions for single-analyte organic acid testing.
Billing Code Overview
CPT code 83921 describes a laboratory test in which a single organic acid analyte is measured. The analyte may be any one of more than 60 identified organic acid compounds. The test is performed on a variety of specimen types, including serum, plasma, urine, amniotic fluid, blood spot, or other specimen types, depending on the analyte requested.
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Service type: Clinical laboratory single-analyte organic acid testing
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Typical site of service: Clinical laboratory or hospital laboratory; specimens may be collected in outpatient, inpatient, or specialty settings depending on clinical need.
Clinical & Coding Specifications
Clinical Context
A 6-year-old child presents to a pediatric metabolic clinic with a history of delayed development, failure to thrive, recurrent vomiting, and episodic lethargy. The clinician suspects an inborn error of metabolism or an acquired metabolic disturbance and orders targeted organic acid testing to evaluate specific metabolites in urine. A urine specimen is collected in the outpatient clinic and sent to the clinical chemistry laboratory. The lab analyst performs 83921 to measure a single organic acid analyte (for example, methylmalonic acid or lactic acid) using gas chromatography–mass spectrometry or liquid chromatography–tandem mass spectrometry. Results are returned to the ordering provider and documented in the electronic medical record; abnormal findings prompt genetics referral, nutritional management, or hospital admission for metabolic stabilization.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing professional interpretation separate from technical component provided by a reference lab. |
TC | Technical component |