Tests are selected based on clinical likelihood. As examples, a patient under age 40 with suspected asthma might just need spirometry pre/post bronchodilator; a young patient without suspicion for heart failure or pulmonary hypertension might not need an ECG or plasma BNP; and a patient with suspected heart failure might not need spirometry. However, some patients will need all tests in this section. | |
Test | Rationale/indications |
Hemoglobin/hematocrit | Anemia can present as dyspnea or reduced exercise tolerance. |
Glucose, blood urea nitrogen, creatinine, electrolytes, phosphate, calcium | For adults with other comorbidities or over age 40, screen for metabolic causes of dyspnea. |
Thyroid stimulating hormone (TSH) | Hyper and hypothyroidism can present as dyspnea or reduced exercise tolerance. |
Spirometry pre/post bronchodilator with or without lung volumes and DLCO | Depending on the likelihood of asthma or COPD and difficulties of travel and scheduling, spirometry pre/post bronchodilator may be ordered initially without full PFTs. Alternatively, full testing (spirometry pre and post bronchodilator, lung volumes, DLCO, ambulatory oximetry) may be more expeditious. Refer to UpToDate table on follow-up testing based on initial results. |
Assess SpO2 (eg, walking ≥200 feet and two flights of stairs)* | Hypoxemia at rest or desaturation with exertion indicates the need to pursue definitive diagnosis. Obtain full PFTs, CXR, BNP, ECG, and possibly echocardiogram. Refer to UpToDate table on follow-up testing based on initial results. |
Chest radiograph | Indicated for most dyspneic patients, particularly those who are over age 40, have suspected heart failure or interstitial disease, or abnormal PFTs. Not needed in routine evaluation of asthma. |
ECG | Indicated for most dyspneic patients over age 40. Not needed in young patients with clear diagnosis of asthma and response to treatment. Refer to UpToDate table on follow-up testing based on initial results. |
Plasma BNP or NT-pro BNP | Useful screening test for HF although not entirely specific; dyspnea due to HF is associated with plasma BNP >400 pg/mL; high negative predictive value for BNP <100 pg/mL, although BNP increases with age. |
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