How do you approach laboratory evaluation in patients with fatigue?

First search for evidence by history and physical examination for any evidence of inflammation. If there is tailor the lab workup rather than ordering tests as screening tools. ESR and CRP to start with. Anything more without a reasonable a priori likelihood of the targeted diagnosis is just asking ...

SORRY FOR THE LENGTH OF THIS RESPONSE...

I have written and spoken extensively about the woeful state of how internal medicine physicians and subspecialists—including rheumatologists—assess and manage chronic fatigue. I recognize that this remains a controversial area of medicine, but it is one that...

Focus on H+P with attention to sleep, current and OTC meds (especially asking about supplements), habits (diet, exercise, alcohol, substances), mood changes and stress, menstrual cycle changes, joint complaints that are new, skin changes/rashes. Counsel on habits, if any, sleep hygiene, and exercise...

History! Lab workup for fatigue is so nonspecific.

Don’t forget to screen for depression, elicit hx of post-exertional malaise (MECFS), orthostatic intolerance (dysautonomia), hives/sensitivities (MCAS), and hypermobility arthralgia (EDS).