Aim To identify the best management strategy for improving the appropriateness of vitamin D, vitamin B12 and folate retesting.

Methods The study was conducted between 3 November 2012 and 8 June 2015, with inpatients and outpatients being considered separately. After an observational reference period (3 November 2012 to 14 September 2013), an information technology (IT)-based permissive strategy (16 September 2013 to 27 July 2014) followed by a limiting strategy was used to manage the demand for inpatient retesting. For outpatients, an educational strategy period (28 July 2014 to 16 December 2014) with direct contact between medical personnel and general practitioners (GPs) was followed by a post-educational period without any restriction. Data from a total of 66 496 patients for vitamin D, 14 618 for vitamin B12 and 14 445 for folate were retrieved from the laboratory IT system. The main outcomes measures were inappropriate vitamin D, vitamin B12 and folate retesting. The minimal retesting intervals were 90 (vitamin D) or 180 days (vitamin B12 and folate).

Results In the absence of a laboratory demand strategy, the frequency of inappropriate retesting for vitamin D, vitamin B12 and folate was 60%, 94% and 93%, respectively, for inpatients, and 27%, 87% and 87%, respectively, for outpatients. A limiting IT-based demand management strategy reduced inappropriate retesting for vitamin D (36%), but not for vitamin B12 and folate. The educational strategy was followed by a reduction in inappropriate retesting among outpatients (16% for vitamin D, 72% for vitamin B12 and folate).

Conclusions Laboratory demand management based on an IT-limiting management strategy or on education of the referring physicians appears helpful in maximising appropriate retesting.