Background 5-Amino salicylate (5-ASA) medications may rarely be associated with a significant decline in renal function and interstitial nephritis. British Society of Gastroenterology guidelines advise regular renal function monitoring for patients taking these drugs.

Aim To assess whether gastroenterologists in Kent were following best practice guidelines regarding the monitoring of their patients on 5-ASA therapy.

Methods Using longitudinal community and regional pathology databases for the Kent population, our renal unit regularly screens a total population of 300 000 for evidence of renal disease. The data extracted are analysed using an automated computerised system to identify patients requiring intervention for kidney disease. All patients taking 5-ASA medication were identified from a population of 300 000. The pathology database was studied to identify the patients on 5-ASA treatment and whether they had had renal function tests.

Results 800 adult patients were identified taking 5-ASA therapy. 612 patients received 5-ASAs for 3 months or more, and these were included in the final analysis. 293 patients had no renal function checks while on treatment. 79 patients had renal function tests less than once every 4 years and 36 patients once every 2–4 years. 204 patients had renal function measurements in 50% or more of years of treatment, of whom 116 were checked every year. Some patients were started on treatment with abnormal results at baseline and some with identified kidney disease continued on their 5-ASAs.

Conclusions The majority of patients receiving 5-ASA compounds do not have regular renal function monitoring. Clinicians are failing to follow best practice guidelines.