Pathology The antistreptolysin O (ASO) titer is used in the diagnosis of: A Acute rheumatoid ahritis B Acute rheumatic fever C Ankylosing spondylitis D Osteoahritis 💡 Explanation The antistreptolysin O (ASO) titer is used in the diagnosis of: ✓ Correct Answer: B. Acute rheumatic fever