CRP and idiopathic pulmonary fibrosis: Notably, the current IPF guidelines routinely recommend performing the independent serological test as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), antinuclear antibodies (ANA), rheumatoid factor (RF), myositis panel, and anti-cyclic citrullinated peptide (ACPA), and consulting a rheumatologist in the case of positivity of those serological tests or if there are clinical manifestations suggesting an underlying rheumatological disease—such as females younger than 60 years [70].