Final answer:
The cluster of symptoms described could be consistent with several conditions, including Lyme disease and various autoimmune disorders. Tests to diagnose these conditions might include serological assays, inflammation markers, and imaging studies.
Step-by-step explanation:
Based on the clinical focus descriptions provided, the student appears to be inquiring about a possible medical diagnosis given a set of symptoms. Specifically, the scenario involves an individual named Kayla with early signs that could be attributed to various diseases, including autoimmune conditions and infections. The worsening symptoms such as joint pain, heart palpitations, facial muscle weakness, stiff neck, and headaches led her physician to consider multiple differential diagnoses, including Lyme disease, despite the absence of a bull's-eye rash. Ankylosing Spondylitis (AS), although not explicitly mentioned in the provided information, is also a condition with symptoms that could overlap with what Kayla is experiencing, particularly joint pain.
To narrow down the diagnosis, a physician might order lab tests for markers of inflammation such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), as well as serological tests for specific autoimmune markers. Imaging such as MRI may be used to assess involvement of joints or other tissues. Additionally, given the concern for Lyme disease, testing for Borrelia burgdorferi, the causative agent of Lyme disease, might be ordered. If Ankylosing Spondylitis were being considered, human leukocyte antigen B27 (HLA-B27) testing might also be utilised.