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v1.0.0
ICD-10 Guide
DiagnosesAcidosis

Acidosis

ICD-10 Coding for Acidosis(E87.21, E87.22, E87.20)

PRIMARY SPECIALTYInternal Medicine
COMPLEXITYHigh
LAST UPDATED09/15/2025
Sam Tuffun, PT, DPT
Physical Therapist | Medical Coding & Billing Contributor

Diagnosis Overview

What is Acidosis?
Acidosis is a condition characterized by an excess of acid in the body fluids, leading to a decrease in blood pH below the normal range of 7.35-7.45. It can be classified into two main types: metabolic acidosis, which occurs due to increased acid production or decreased bicarbonate, and respiratory acidosis, resulting from impaired carbon dioxide elimination. Key clinical points include: 1) Metabolic acidosis can arise from conditions such as diabetic ketoacidosis or renal failure. 2) Respiratory acidosis is often seen in chronic obstructive pulmonary disease (COPD) or severe asthma exacerbations. 3) Symptoms may include confusion, lethargy, and shortness of breath. Typical use cases for acidosis diagnosis codes include patients presenting with altered mental status, respiratory distress, or metabolic derangements. The etiology can vary widely, and the pathophysiology involves disruptions in acid-base balance, leading to compensatory mechanisms by the lungs and kidneys. Clinical presentation may include tachypnea, hyperkalemia, and decreased urine output, necessitating prompt diagnosis and management.

Key Clinical Considerations:

  • Diagnosis requires clinical evidence of acidemia, typically confirmed by arterial blood gas analysis showing pH < 7.35.
  • Signs and symptoms may include rapid breathing, confusion, fatigue, and headache.
  • Resolution criteria include normalization of blood pH and improvement of underlying causes.
  • Laboratory findings may show elevated anion gap in metabolic acidosis or elevated CO2 levels in respiratory acidosis.

Clinical Information

Clinical Criteria & Documentation Requirements

  • Documentation must include the specific type of acidosis, underlying causes, and clinical manifestations.
  • Compliant documentation: 'Patient diagnosed with metabolic acidosis due to renal failure.' Non-compliant: 'Patient has acidosis.'
  • Documentation template phrases: 'Patient presents with symptoms consistent with metabolic acidosis due to [specific cause].'
  • Medical necessity documentation should justify the need for diagnostic tests and treatments related to acidosis.

Coding Guidelines

Usage Guidelines & Examples

  • Use E87.20 for unspecified acidosis when the type is not specified; E87.21 for metabolic acidosis; E87.22 for respiratory acidosis.
  • Do not use these codes for conditions like alkalosis or other unrelated acid-base disorders.
  • Correct usage example: 'Patient admitted with E87.21 due to diabetic ketoacidosis.' Incorrect: 'Patient has acidosis without specifying type.'
  • Common errors include failing to specify the type of acidosis or misclassifying the underlying cause.

Code Exclusions

Important Exclusions

  • Excluded conditions include alkalosis (E87.3) and other unrelated metabolic disorders.
  • Alternative codes for exclusions may include E87.29 for other specified acid-base disorders.
  • Common exclusion errors involve misclassifying alkalosis as acidosis; corrective example: 'Patient has metabolic alkalosis, not acidosis.'
  • Certain conditions are excluded due to differing pathophysiological mechanisms.

Related ICD-10 Codes

Primary Codes
E87.20
Acidosis, unspecified
E87.21
Metabolic acidosis
E87.22
Respiratory acidosis
Ancillary Codes
R65.20
N18.3
Differential Codes
E87.22
E87.21

Related CPT Codes

CPT codes will be available in a future update.

Specialty Focus

Primary Specialty

Internal Medicine

Specialty Applications

  • This diagnosis applies to patients with conditions leading to acid-base imbalances, such as renal failure or respiratory diseases.
  • Appropriate in clinical scenarios involving acute respiratory distress or metabolic derangements.
  • Applicable in various practice settings, including inpatient, outpatient, and emergency departments.
  • Specialty considerations include internal medicine, nephrology, and pulmonology.

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: 'Acidosis diagnosed based on arterial blood gas analysis showing pH < 7.35.'

Template 2

Template: 'Patient presents with confusion and rapid breathing consistent with metabolic acidosis.'

Template 3

Template: 'Diagnostic criteria met: arterial blood gas shows metabolic acidosis with anion gap.'

Template 4

Template: 'Treatment plan includes bicarbonate therapy for metabolic acidosis due to renal failure.'

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 documentation should include the type of acidosis, underlying causes, and clinical symptoms.

When should this code be used vs similar codes?

Use specific codes for metabolic or respiratory acidosis based on clinical presentation and lab results.

What are common billing issues with this code?

Reimbursement issues may arise from lack of specificity or inadequate documentation supporting medical necessity.

What procedures are commonly associated?

Related CPT codes may include arterial blood gas analysis and treatments for underlying causes.