The application provides methods for determining a patient's risk for developing fibrosis or a fibrosis-related disorder. Concentrations of C reactive protein (CRP) and serum amyloid protein (SAP) are measured from a biological sample to determine the SAP-to-CRP ratio. This ratio can then be compared with one or more SAP-to-CRP reference ratios to determine a patient's risk for developing a fibrosis related disorder. The diagnostic methods can also be used to determine the severity of fibrosis in a patient afflicted with such a disease. Furthermore, methods for treating patients having a fibrosis-related disorder are provided. For example, a patient that has a lower SAP-to-CRP ratio than one or more reference values may be treated with an SAP agonist and/or CRP antagonist to treat or prevent a fibrosis disorder. The methods may further comprise determining the R131/H131 polymorphism of FcγRIIA as a risk factor for developing fibrosis or a fibrosis-related disorder.