What Biochemical Tests Are Recommended For A Diabetic Elderly Man With Chest Pain, Back Pain, Urinary Retention, Swelling, And Fever?

Progressive assessment A 76 year old known diabetic man presents to the emergency department as a referral with complaints of severe chest pain, back pain and failure to pass urine for 1 day. He also has bilateral lower limb swelling but with one limb more markedly swollen than the other. He reports a history of fever and chills for the past two days. Prior to referral, a blood smear for malaria was done and results were negative. what is the biochemical investigations you would perform in this patient to aid in diagnosis, including their rationale.