A previous paper has suggested that C-reactive protein (CRP) is a useful serum marker for determining the likelihood of a patient with renal colic requiring surgical intervention, the cut-off level being >28mg/l (specificity 88.9%, sensitivity 75.8%). This prospective observational study studied 55 patients who were admitted with proven acute renal colic (on CT KUB) over a three-month period. The investigators aimed to test this theory for their patient population. All patients had their CRP checked on admission and on a daily basis. Intervention was determined by the patient’s surgical team who were not blinded to CRP. In total 44% (24) patients proceeded to have a surgical intervention, the majority having ureteric stents (22). The remaining 31 patients were managed conservatively. When the results were analysed no statistically significant difference was found between the CRP at presentation in the intervention and non-intervention group (p=0.06).There did, however, appear to be a significantly higher serum level at some point during the inpatient stay in those that went on to have intervention (mean 95mg/l) compared to the conservatively managed group (26mg/l) (p<0.001). This paper showed quite a high intervention rate (44%). The original paper had an intervention rate of 26%. I wonder whether this contributed to the difference in outcomes with regard to CRP level. It is an attractive idea to think that an elevated CRP on admission could predict the need for future intervention as it could help prevent nephron loss in some patients and also help others to be managed more confidently in the outpatient setting. It may be worth repeating this study in a larger group of patients.