Summary & Overview

CPT 82438: Chloride Measurement in CSF or Sweat

CPT code 82438 represents a clinical laboratory assay that measures chloride concentration in non-blood, non-urine specimens such as cerebrospinal fluid (CSF) or sweat. This electrolyte measurement informs diagnosis and management of neurological, metabolic, and electrolyte disorders where CSF or sweat chloride levels are clinically relevant. Nationally, accurate coding for specialized laboratory assays supports appropriate clinical interpretation, billing consistency, and laboratory quality monitoring.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find context on the clinical purpose of the test, typical sites of service where the assay is performed, and payer coverage considerations. The publication outlines common billing modifiers associated with clinical laboratory services and highlights what is available about related administrative elements.

This summary provides a concise clinical and billing overview: what the code represents, why the measurement matters for patient care, and which major payers are relevant for reimbursement and coverage considerations. Data not available in the input is noted where administrative details, associated taxonomies, ICD-10 diagnoses, and related codes are not provided.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare82438CPTLaboratoryElectrolyte TestingChlorideCerebrospinal FluidSweat TestClinical Chemistry

Billing Code Overview

CPT code 82438 describes a laboratory measurement of chloride concentration in non-blood, non-urine specimens such as cerebrospinal fluid (CSF) or sweat. The test quantifies an important electrolyte—chloride—that contributes to maintaining the body's electrolyte and acid-base balance. Results can aid in diagnosing and monitoring conditions that affect CSF composition or electrolyte handling.

Service type: Clinical laboratory test — electrolyte analysis of non-blood, non-urine body fluids
Typical site of service: Hospital laboratory, independent clinical laboratory, or specialized diagnostic lab processing CSF, sweat, or other non-blood/non-urine specimens

Data not available in the input.

Clinical & Coding Specifications

Clinical Context

A typical patient is a child or adult evaluated for neurologic signs of central nervous system infection, inflammation, electrolyte disorder, or cystic fibrosis screening. A lumbar puncture is performed in an emergency department, inpatient unit, or outpatient ambulatory clinic to obtain cerebrospinal fluid (CSF). The specimen is sent to the clinical laboratory where a lab analyst performs quantitative measurement of chloride in the CSF using ion-specific electrodes or coulometric titration. Results are used alongside CSF glucose, protein, cell count, culture, and microbiology to assess conditions such as meningitis, subarachnoid hemorrhage, demyelinating disease, or to monitor CSF electrolyte disturbances. Typical workflow: specimen collection and labeling at bedside → transport to lab with appropriate chain-of-custody and refrigerated transport when indicated → accessioning and verification by laboratory staff → analytical measurement of CSF chloride (CPT 82438) → result validation and release to ordering clinician and medical record. Typical sites of service: hospital inpatient, emergency department, outpatient hospital clinic, and reference laboratory. Common clinical indications include suspected infectious meningitis, unexplained neurologic deterioration, evaluation of CSF shunt function, or adjunct testing in metabolic and electrolyte disorders.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when separate billing for the professional interpretation portion applies (rare for this lab test).
`59`	Distinct procedural service	Use when this chloride measurement is a distinct, separate service from other billed laboratory tests when payer requires modifier.
`90`	Reference (outside) laboratory	Use when testing is performed by an outside/reference laboratory and billing requires identification.
`91`	Repeat clinical diagnostic laboratory test	Use when a repeat chloride measurement is performed on the same day to confirm or trend results.
`52`	Reduced services	Use if testing was partially reduced and full service not performed (rare).
`53`	Discontinued procedure	Use if specimen collection or testing was begun but discontinued for documented clinical reasons.
`59`	Distinct procedural service	Use when lab wants to indicate this assay is separate from other assays on same day (duplicate deliberately listed above for clinical emphasis).
`TC`	Technical component	Use when billing only the technical component of the test (instrumentation, processing) separate from professional component.
`90`	Reference laboratory (alternate use)	Use to identify outside lab performing the technical component when billing entity differs (see payer rules).
`91`	Repeat (alternate use)	Use for repeat measurements to document reliability or post-intervention monitoring.

Taxonomy Code	Specialty	Notes
2080S0002X	Pathology	Clinical pathologists and laboratory medicine physicians oversee CSF chemistry testing and result interpretation.
208000000X	Clinical Laboratory	Medical technologists and laboratory directors who perform and validate quantitative electrolyte assays.
207L00000X	Neurology	Ordering neurologists who request CSF chloride as part of neurologic diagnostic evaluation.
2084P0800X	Emergency Medicine	Emergency physicians who order CSF studies during acute presentations for meningitis or altered mental status.
207K00000X	Pediatrics	Pediatricians and pediatric subspecialists ordering CSF chloride in children, including cystic fibrosis screening contexts.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`G00.9`	Bacterial meningitis, unspecified	CSF chloride measured as part of CSF chemistry panel when evaluating suspected meningitis.
`G03.9`	Meningitis, unspecified	General indication for CSF analysis including chloride to assess inflammatory or infectious processes.
`G96.0`	Ventricular shunt malfunction	CSF studies including chloride help evaluate shunt function and composition of CSF in symptomatic patients.
`R41.0`	Disorientation, unspecified	Neurologic symptoms that prompt lumbar puncture and CSF electrolyte measurement.
`E87.6`	Hypokalemia	Electrolyte disturbances may be evaluated systemically and in CSF when central causes are considered.
`E87.5`	Hyperkalemia	Related systemic electrolyte disorders evaluated in conjunction with CSF studies when clinically indicated.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`36415`	Collection of venous blood by venipuncture	Often performed alongside CSF testing for comparative serum electrolyte measurements and infectious serologies.
`62270`	Spinal puncture, lumbar, diagnostic	Performed to obtain cerebrospinal fluid that is sent for `CPT 82438` chloride measurement.
`80053`	Comprehensive metabolic panel	May be ordered concurrently to assess systemic electrolyte status that complements CSF chloride results.
`82746`	Ionized calcium; whole blood	Example of other electrolyte testing frequently ordered in parallel when evaluating metabolic causes of neurologic symptoms.
`87070`	Culture, any source, bacterial, quantitative	CSF culture testing commonly performed alongside chloride to identify infectious etiologies.