What labs for Shortness Of Breath (SOB)?

From the Guidelines

Shortness of breath (SOB) labs include a complete blood count, chemistry panel, thyroid function tests, and BNP or NT-proBNP levels.

Initial Evaluation

The initial evaluation of SOB is aimed at determining the underlying cause, which can be cardiovascular, pulmonary, or a combination of both.

• A chest radiograph is typically performed in the initial workup, as it can help guide further investigation and sometimes eliminate the need for additional tests 1.
• Pulmonary function tests, such as spirometry, may also be performed to assess lung function.

Laboratory Tests

The following laboratory tests are commonly ordered in the evaluation of SOB:

• Complete blood count (CBC) to rule out anemia or infection
• Chemistry panel to assess electrolyte levels and kidney function
• Thyroid function tests to evaluate for thyroid disease
• BNP or NT-proBNP levels to assess for heart failure, with the following cut-off values:
  • BNP < 100 pg/dL or NT-proBNP < 300 pg/dL: acute heart failure syndrome unlikely 1
  • BNP > 500 pg/dL or NT-proBNP > 1,000 pg/dL: acute heart failure syndrome likely 1

Additional Tests

Additional tests, such as electrocardiogram (ECG) and echocardiogram, may be ordered based on the clinical presentation and initial test results 1. In some cases, broncho provocation testing may be performed to assess for asthma or other respiratory conditions 1. Cardiopulmonary exercise testing (CPX) may also be ordered to evaluate exercise tolerance and assess for cardiovascular or pulmonary limitations 1.

From the Research

Labs for Shortness Of Breath (SOB)

The following labs can be used to diagnose the cause of shortness of breath:

• Troponin I: to diagnose acute myocardial infarction (MI) 2
• Myoglobin: to diagnose acute myocardial infarction (MI) 2
• Creatinine kinase-myocardial band isoenzyme (CK-MB): to diagnose acute myocardial infarction (MI) 2
• D-dimer: to diagnose pulmonary embolism (PE) 2
• B-type natriuretic peptide (BNP): to diagnose heart failure (HF) 2

Additional Tests

Other tests that may be used to evaluate shortness of breath include:

• Pulmonary function tests (PFTs): to evaluate lung function 3
• Six-minute walk test: to evaluate exercise tolerance 3, 4
• Oxygen cost diagram: to evaluate dyspnea 4
• Visual Analog Scale: to evaluate dyspnea 4
• Borg Scale: to evaluate dyspnea 4
• Baseline Dyspnea Index (BDI) and Transition Dyspnea Index: to evaluate dyspnea 4
• UCSD Shortness of Breath Questionnaire (SOBQ): to evaluate dyspnea 4
• American Thoracic Society Dyspnea Scale: to evaluate dyspnea 4