Thanks for your question and certainly interesting. There are a couple of ways that joint pains can be investigated, including blood tests, ultrasound examinations and X-rays. Often, this is preceded by a thorough clinical assessment including history and physical examination. unfortunately, in some patients with conditions such as RA, blood tests can be negative at first presentation and hence the clinical assessment is really important.
If you are concerned about arthritis, I would suggest seeing a GP, MSK physician. They can perform investigations and refer onwards if necessary. Treatments can vary according to severity and the underlying problem.
I hope this helps.
BW
Dr Dinesh