Impact of Mean Cell Hemoglobin on Hb A1c-Defined Glycemia Status.
BACKGROUND
Several hematological alterations are associated with altered hemoglobin A1c(Hb A1c). However, there have been no reports of their influence on the rates of exceeding standard Hb A1cthresholds by patients for whom Hb A1cdetermination is requested in clinical practice.


METHODS
The initial data set included the first profiles (complete blood counts, Hb A1c, fasting glucose, and renal and hepatic parameters) of all adult patients for whom such a profile was requested between 2008 and 2013 inclusive. After appropriate exclusions, 21844 patients remained in the study. Linear and logistic regression models were adjusted for demographic, hematological, and biochemical variables excluded from the predictors.


RESULTS
Mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV) correlated negatively with Hb A1c. Fasting glucose, MCH, and age emerged as predictors of Hb A1cin a stepwise regression that discarded sex, hemoglobin, MCV, mean corpuscular hemoglobin concentration (MCHC), serum creatinine, and liver disease. Mean Hb A1cin MCH interdecile intervals fell from 6.8% (51 mmol/mol) in the lowest (≤27.5 pg) to 6.0% (43 mmol/mol) in the highest (>32.5 pg), with similar results for MCV. After adjustment for fasting glucose and other correlates of Hb A1c, a 1 pg increase in MCH reduced the odds of Hb A1c-defined dysglycemia, diabetes and poor glycemia control by 10%-14%.


CONCLUSIONS
For at least 25% of patients, low or high MCH or MCV levels are associated with increased risk of an erroneous Hb A1c-based identification of glycemia status. Although causality has not been demonstrated, these parameters should be taken into account in interpreting Hb A1clevels in clinical practice.
Department of Biochemistry and Molecular Biology, ssegade@telefonica.net.|University Hospital Clinical Biochemistry Laboratory.
Santiago
S
Rodriguez-Segade
University Hospital Clinical Biochemistry Laboratory.
Javier Rodriguez
JR
Garcia
Division of Endocrinology.
José M
JM
García-López
Clinical Epidemiology Unit, Universidade de Santiago de Compostela, 15782-Santiago de Compostela, A Coruña, Spain.
Francisco
F
Gude
Division of Endocrinology.|Physiopathology of Obesity and Nutrition Biomedical Research Network Consortium; and.
Felipe F
FF
Casanueva
the Division of Pneumology, University Hospital Clinical Complex (CHUAC), A Coruña, Spain.
Santiago
S
Rs-Alonso
Department of Biochemistry and Molecular Biology.
Félix
F
Camiña
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000032:analysis*; D003920:Diabetes Mellitus / Q000097:blood* / Q000175:diagnosis*; D004912:Erythrocytes / Q000737:chemistry*; D005215:Fasting; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged
D001786:Blood Glucose; D006442:Glycated Hemoglobin; D006454:Hemoglobins