Sarcoidosis: An FP’s primer on an enigmatic disease

Laboratory studies

Multiple abnormalities may be seen in sarcoidosis, and specific lab tests may help support a diagnosis of sarcoidosis or detect organ-specific disease activity (TABLE 4).^22,23,25,38 However, no consistently accurate biomarkers exist for use in clinical practice. An angiotensin-converting enzyme (ACE) level greater than 2 times the upper limit of normal may be helpful; however, sensitivity remains low, and genetic polymorphisms can influence the ACE level.²⁵ Biomarkers sometimes used to assess disease activity are serum interleukin-2 receptor, neopterin, chitotriosidase, lysozyme, KL-6 glycoprotein, and amyloid A.²¹

Additional tests to assess specific features or organ involvement

Pulmonary function testing (PFT) is reviewed in detail below under “pulmonary sarcoidosis.”

Electrocardiogram (EKG)/transthoracic echocardiogram (TTE). EKG abnormalities—conduction disturbances, arrhythmias, or nonspecific ST segment and T-wave changes—are the most common nonspecific findings.³⁰ TTE findings are also nonspecific but have value in assessing cardiac chamber size and function and myocardial involvement. TTE is indeed the most common screening modality for sarcoidosis-associated pulmonary hypertension (SAPH), which is definitively diagnosed by right heart catheterization (RHC). Further evaluation for cardiac sarcoidosis can be done with cardiac MRI or fluorodeoxyglucose PET in specialized settings.

Lumbar puncture (LP) may reveal lymphocytic infiltration in suspected neurosarcoidosis, but the finding is nonspecific and can reflect infection or malignancy. Oligoclonal bands may also be seen in about one-third of neurosarcoidosis cases, and it is imperative to rule out multiple sclerosis.²⁸

Pulmonary sarcoidosis

Pulmonary sarcoidosis accounts for most of the morbidity, mortality, and health care use associated with sarcoidosis.^39,40

Continue to: Pathology of early and advanced pulmonary sarcoidosis