Introduction Vitamin B12 has been identified as a micronutrient of interest for older adults (1-3), with deficiency primarily caused by either inadequate intake (3) or lack of absorption due to atrophic gastritis, which is highly prevalent in this segment of the population (3). Nonspecific symptoms associated with B12 deficiency make diagnosis challenging and include: depression (4-8), other psychiatric symptoms (4), impaired neurotransmitter and monoamine synthesis (4), cognitive decline or dementia (5-7), memory problems (8), balance and mobility issues due to peripheral neuropathy (5, 7).These are in addition to classic symptoms of vitamin B12 deficiency including macrocytic megaloblastic anemia, and degeneration of the spine (4-6). One particularly vulnerable group for B12 deficiency is older adults (65 years or older) living in long-term care (LTC), where malnutrition affects up to 65% (9). While decreased absorption is the main cause of B12 deficiency, low intake is still a concern especially as absorptive changes with age likely increase B12 requirements. Low micronutrient intake commonly coincides with protein-energy malnutrition and there is a significant potential for deficiency. Generally, older adults in LTC are more vulnerable to micronutrient malnutrition due to any combination of: inadequate micronutrient content of the meal resulting from menu planning challenges; low food intake resulting from functional impairment, slow eating, taste changes, poor appetite (10, 11); and the high use of medications (12). Prevalence of B12 deficiency (or marginal status) in community-living older adults (age 65+) is estimated at up to 40% depending on the diagnostic criteria used (1, 13, 14). While there is no consistency in cut-points used to define status, typically, B12 deficiency is defined as a B12 blood serum concentration below a very low value (e.g., <150pmol/L (14)) and marginal status as a range of concentrations between this deficient cut-point and normal status (e.g., 150-250 pmol/L; normal >250pmol/L (14)). Relatively few studies have reported on B12 deficiency prevalence in LTC and it is anticipated to relatively high due to challenges, due to challenges in eating and deficits in menu planning (15), especially as there are relatively few foods in which B12 naturally exists (i.e., only in animal products) (16); LTC estimates outside of Canada range from 7% (17) to 34% (18). Only two studies from Canada are published, one study in a LTC hospital finding 7% and 35% with low and low normal B12 concentrations (17) while another study found 14% and 39% had low and low normal concentrations at admission to LTC (19). As symptoms of vitamin B12 deficiency are subtle, nonspecific and are frequently unrecognized or misdiagnosed (13, 14) and classic symptoms as such are unreliable for diagnosis (13), deficiency may only be identified with regular testing. Prior estimates of prevalence were primarily based on samples of residents that had been admitted for a period of time. Currently it is unknown if and when LTC does routine testing to screen for B12 deficiency. This potentially avoidable deficiency may provide an opportunity for improving health outcomes of LTC residents. However, a gap exists in our understanding of LTC practices VARIABILITY IN ONTARIO LONG-TERM CARE PRACTICES FOR SCREENING AND TREATMENT OF VITAMIN B12 DEFICIENCY K.J. PFISTERER 1,2 , M.T. SHARRATT 1,2 , G.G. HECKMAN 1,2 , H.H. KELLER 1,2 1. University of Waterloo, Waterloo, ON, Canada; 2. Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON, Canada. Corresponding author: Heather H. Keller, 200 University Avenue West, Burt Matthews Hall 1106, Waterloo, ON, Canada, N2L 3G1, Email: hkeller@uwaterloo.ca, Telephone: (519) 888-4567 ext. 31783, Fax: (519) 746-6776 Abstract: Background: Vitamin B12 deficiency is avoidable through screening and treatment. Deficiency in long-term care impacts ~35% of residents, yet it remains unclear as to what long-term care homes are doing to address this issue. Objective: For the first time, to describe the state of B12 screening and treatment protocols in Ontario long-term care homes, influence of geography and corporate structure on protocols, and the proportion of residents who are currently under treatment. Design: This cross-sectional study used stratified random sampling. Setting: Ontario long-term care homes. Participants: Forty-five standardized phone interviews were completed with the directors of nursing care. Measurements: The following measurements were collected: home demographics (geography, for-profit status etc.), protocols pertaining to vitamin B12 testing, treatment, the cut- point each home uses to define B12 deficiency, proportion of residents receiving B12 and the treatment method (intramuscular injection vs. oral). Results: Cut-off values for determination of B12 deficiency varied (31% <156 pmol/L). Admission and follow-up B12 testing were routinely conducted in 66% (30/45) and 88% (35/40) of long-term care homes respectively. On average 25 ± 16% of current residents received treatment (41/45 homes reporting). Conclusions: Variability in detection and treatment of B12 deficiency in LTC, potentially places residents at risk for undetected deficiency. Regular testing and monitoring beginning at admission may provide a solution, however, there is a need both for further studies targeted at addressing the effect of treatment on improved clinical outcomes as well as a formal cost-benefit analysis for screening and subsequent treatment. Key words: Vitamin B12 deficiency, long-term care, nursing home, screening. 64 The Journal of Nursing Home Research Sciences Volume 2, 2016 Received April 18, 2016 Accepted for publication May 17, 2016 Jour Nursing Home Res 2016;2:64-70 Published online July 1, 2016, http://dx.doi.org/10.14283/jnhrs.2016.9