The field of physiatry requires the expertise of evaluating and managing disease states, injuries, and disabilities that alter the functional level of an individual. Physiatrists need to be familiar with the fundamentals of diagnostic testing that include several basic tests and diagnostic algorithms inherent to the general practice of medicine, as well as some specialized tests that are unique to physiatry and related specialties. The uniqueness in the physiatric approach to diagnostic testing often lies in the consideration of not only how clinically relevant the diagnostic test is, but also in how such testing can lead to identifying better treatment options that improve the functional outcome of the patient. Diagnostic testing can be used to diagnose a specific disorder, help in the surveillance and monitoring of disease progression, or help confirm diagnoses, thereby aiding the physiatrist in narrowing the differential diagnosis. This overview will focus on tests commonly performed within the scope of practice of physical medicine and rehabilitation (PM&R).
Laboratory testing applicable to physiatrists includes simple blood tests, which assess electrolyte abnormalities, kidney or liver function, and blood cell counts. In addition, specific tests are applicable to certain patient populations. Wound management requires testing periodically for pre-albumin and inflammatory markers (C-reactive protein [CRP] and erythrocyte sedimentation rate [ESR]) to monitor progression of wound healing and ensuring optimal nutritional status for surgery, as well as assessing for the presence of infection.
Muscle disease markers like creatine phosphokinase (CPK), alkaline phosphatase, and the aforementioned inflammatory markers can be used to aid in diagnosis of inflammatory muscle diseases. Laboratory tests that may aid in the evaluation of inflammatory arthritides include rheumatoid factor (RF), antinuclear antigen (ANA), serum protein electrophoresis (SPEP), and urine protein electrophoresis (UPEP).
Urine analysis and urine culture are used in both inpatient and outpatient settings particularly to assess for underlying infection. Symptoms that might prompt a physiatrist to order these tests include dysuria, frequency of urination, incontinence, leaking of urine between voluntary voids, or when complaining of constitutional symptoms like fever, chills, and acutely altered mental status. Urine cultures should be obtained prior to starting antibiotics and followed up for organism speciation and susceptibilities to more narrowly focus antibiotic treatment.
Disease-specific biomarkers are relevant when evaluating skeletal muscle pathology. A reliable protein biomarker of muscle damage should ideally be (1) specifically expressed at a high concentration level in intracellular domains of healthy and undamaged skeletal muscle tissues; (2) highly specific in its cellular or subcellular localization under normal conditions; (3) fiber type specific within fast versus slow muscle populations; (4) varied in its extent of extramuscular presence according to the type and intensity of muscle damage; (5) able to differentiate between acute versus chronic muscle injury; and (6) a protein species that can be easily and cost-efficiently assayed by standard methodology.1 Although many are helpful as sensitive markers of muscle damage (creatine ...