Infrequency of low red blood cell (RBC) folate levels despite no folate fortification program: a study based on results from routine requests for RBC folate

Abstract

We investigated the prevalence of a low level of red blood cell (RBC) folate in individuals suspected to be deficient and further evaluated the clinical consequence of identifying an individual with a low folate level in a population where no fortification with folate has been introduced. We conducted a retrospective review of all RBC folate analyses requested in one of the university hospitals in Denmark and identified patients with abnormally low (<350 nmol/L) and high (>1700nmol/L) folate levels. For requests from the hospital, we evaluated the clinicians' response to a decreased level of folate. A total of 12,932 RBC folates requested from the hospital (26%) or from general practitioners (GPs) (74%) were investigated. RBC folate levels were low in a comparable fraction of those requested from the hospital (1.7%) and from the GPs (1.3%). A high level of RBC folate was observed more often than a low RBC folate and occurred considerably more frequently (p<0.0001) in patients referred from the hospital (4.9%) than amongst those referred from GPs (1.2%). The clinicians' response rate to a low folate was around 60% and occurred more often for patients with a low level of cobalamins than in other patients. Low RBC folate values are rare in Danish patients despite no folate fortification program. Further, the clinical reaction to a low folate value is unexpectedly low.