ICD-10 Guide

Abnormal Pulmonary Function Test

ICD-10 Coding for Abnormal Pulmonary Function Test(R94.2, J44.9)

PRIMARY SPECIALTYPulmonology

COMPLEXITYHigh

LAST UPDATED09/15/2025

Sam Tuffun, PT, DPT

Physical Therapist | Medical Coding & Billing Contributor

Diagnosis Overview

What is Abnormal Pulmonary Function Test?

Abnormal pulmonary function tests (PFTs) indicate deviations from normal lung function, often revealing underlying respiratory conditions. Key clinical points include: 1) PFTs assess lung volumes, capacities, and airflow; 2) Abnormal results may suggest conditions such as asthma, COPD, or restrictive lung disease; 3) PFTs are critical in preoperative evaluations and monitoring chronic lung diseases. Etiology can range from environmental factors, such as smoking or pollution, to genetic predispositions. Pathophysiology often involves airway obstruction or restriction due to inflammation or structural changes in lung tissue. Clinical presentation may include symptoms like dyspnea, wheezing, or chronic cough, prompting further investigation through PFTs to guide diagnosis and management. Typical use cases for this diagnosis code include patients presenting with respiratory symptoms, those undergoing evaluation for lung surgery, or individuals with known chronic lung diseases requiring monitoring.

Key Clinical Considerations:

Diagnosis requires abnormal results from spirometry, lung volume measurements, or diffusion capacity tests.
Signs include decreased FEV1/FVC ratio, reduced total lung capacity, or impaired diffusion capacity.
Resolution criteria may involve normalization of PFT results following treatment or lifestyle changes.
Imaging findings may include chest X-rays or CT scans showing structural lung changes correlating with PFT results.

Clinical Information

Clinical Criteria & Documentation Requirements

Documentation must include specific PFT results, clinical symptoms, and the rationale for testing.
Compliant documentation: 'PFTs indicate obstructive pattern consistent with COPD.' Non-compliant: 'PFTs were done.'
Template phrases: 'Patient's PFT results show [specific findings] consistent with [diagnosis].'
Medical necessity requires documentation of symptoms and clinical rationale for PFTs.

Coding Guidelines

Usage Guidelines & Examples

Use R94.2 for abnormal PFTs without a specific diagnosis; use J44.9 for COPD-related abnormalities.
Do not use these codes for normal PFT results or unrelated respiratory symptoms.
Correct usage: 'Abnormal PFTs indicating obstructive lung disease (R94.2)'; Incorrect: 'PFTs normal (not coded).'
Common errors include coding without correlating clinical findings; ensure all documentation supports the diagnosis.

Code Exclusions

Important Exclusions

Excluded conditions include normal pulmonary function tests and acute respiratory infections.
Alternative codes for exclusions may include J00 (acute nasopharyngitis) for unrelated symptoms.
Common exclusion errors: coding R94.2 for normal results; ensure clear documentation of abnormal findings.
Certain conditions are excluded to maintain specificity in coding for abnormal results.

Specialty Focus

Primary Specialty

Pulmonology

Specialty Applications

Applies to patients with suspected or diagnosed respiratory disorders.
Appropriate in clinical scenarios such as preoperative assessments or chronic disease management.
Variations in practice settings include outpatient clinics for routine monitoring and inpatient settings for acute evaluations.
Specialty-specific considerations include pulmonology, primary care, and sleep medicine.

Coding Complexity

High Complexity

This diagnosis requires careful attention to:

Comprehensive clinical documentation
Accurate code selection based on clinical criteria
Proper exclusion considerations
Specialty-specific coding guidelines

Documentation

Documentation Templates

Template 1

Template: 'Abnormal pulmonary function test results indicate [specific findings].'

Template 2

Template: 'Patient presents with [symptoms] consistent with abnormal PFT results.'

Template 3

Template: 'Diagnostic criteria met: [specific findings from PFT].'

Template 4

Template: 'Treatment plan includes [interventions] for abnormal pulmonary function.'

Billing Information

Billing Considerations

Ensure proper documentation for billing
Verify code specificity requirements
Check for any additional codes needed
Review payer-specific guidelines

Common Issues

Insufficient clinical documentation
Incorrect code selection
Missing supporting diagnoses
Timing and frequency documentation

Frequently Asked Questions

What documentation is required for this code?

Detailed PFT results, clinical symptoms, and the rationale for testing.

When should this code be used vs similar codes?

Use R94.2 for abnormal tests without a specific diagnosis; use J44.9 for COPD.

What are common billing issues with this code?

Reimbursement may be denied if documentation does not support medical necessity.

What procedures are commonly associated?

Related CPT codes include 94010 for spirometry and 94620 for PFT interpretation.

What is Abnormal Pulmonary Function Test?

Key Clinical Considerations:

Diagnosis requires abnormal results from spirometry, lung volume measurements, or diffusion capacity tests.
Signs include decreased FEV1/FVC ratio, reduced total lung capacity, or impaired diffusion capacity.
Resolution criteria may involve normalization of PFT results following treatment or lifestyle changes.
Imaging findings may include chest X-rays or CT scans showing structural lung changes correlating with PFT results.

Abnormal Pulmonary Function Test

Diagnosis Overview

Key Clinical Considerations:

Clinical Information

Clinical Criteria & Documentation Requirements

Coding Guidelines

Usage Guidelines & Examples

Code Exclusions

Important Exclusions

Related ICD-10 Codes

Related CPT Codes

Specialty Focus

Primary Specialty

Specialty Applications

Coding Complexity

Documentation

Documentation Templates

Template 1

Template 2

Template 3

Template 4

Billing Information

Billing Considerations

Common Issues

Frequently Asked Questions

What documentation is required for this code?

When should this code be used vs similar codes?

What are common billing issues with this code?

What procedures are commonly associated?

Abnormal Pulmonary Function Test

Diagnosis Overview

Key Clinical Considerations:

Clinical Information

Clinical Criteria & Documentation Requirements

Coding Guidelines

Usage Guidelines & Examples

Code Exclusions

Important Exclusions

Related ICD-10 Codes

Related CPT Codes

Specialty Focus

Primary Specialty

Specialty Applications

Coding Complexity

Documentation

Documentation Templates

Template 1

Template 2

Template 3

Template 4

Billing Information

Billing Considerations

Common Issues

Frequently Asked Questions

What documentation is required for this code?

When should this code be used vs similar codes?

What are common billing issues with this code?

What procedures are commonly associated?