43 year old lady who has hyperlipidemia and hypertension has 12 month history of migratory polyarthritis. No previous infective symptoms or new medications. She has also developed a hypersensitivity rash. No constitutional symptoms. No family history. CRP 30, ESR 25. RF, CCP ab negative. ANA, ENA, dsDNA negative.

What other investigations do you think would be warranted?