title: Relationships of serum free thyroxine and erythrocyte measures in euthyroid HFE C282Y homozygotes and control subjects: the HEIRS study.
abstract: Hemoglobin (Hb) levels and mean corpuscular volume (MCV) are abnormal in some persons with hemochromatosis or thyroid disorders. We sought to determine whether serum free thyroxine (T4) affects erythrocyte measures in euthyroid adults with or without C282Y homozygosity. We evaluated 488 white HFE C282Y homozygotes and controls (no HFE C282Y or H63D; normal serum iron measures) identified in screening; we excluded those with thyroid disorders, anemia, erythrocytosis, or serum ferritin (SF) <34 pmol/l. In the remaining 141 C282Y homozygotes and 243 controls, we evaluated correlations of log(10) free T4 with Hb, RBC, MCV, and red blood cell distribution width (RDW). C282Y homozygotes had lower mean age, higher mean Hb, MCV, and log(10) SF, and lower mean RBC and RDW than controls; mean log(10) free T4 did not differ significantly. In HFE C282Y homozygotes, there was no significant correlation of log(10) T4 with erythrocyte measures. In controls, there was a positive correlation of log(10) T4 with Hb (P = 0.0096) and a negative correlation with RDW (P = 0.0286). Among euthyroid white adults without iron deficiency, there are significant correlations of log(10) free T4 with Hb and RDW in controls, but not in HFE C282Y homozygotes.
authors.affiliation: Southern Iron Disorders Center, Birmingham, AL 35209, USA. ironmd@dnamail.com
authors.forename: J C
authors.initials: JC
authors.lastname: Barton
authors.forename: C
authors.initials: C
authors.lastname: Leiendecker-Foster
authors.forename: D M
authors.initials: DM
authors.lastname: Reboussin
authors.forename: P C
authors.initials: PC
authors.lastname: Adams
authors.forename: R T
authors.initials: RT
authors.lastname: Acton
authors.forename: J H
authors.initials: JH
authors.lastname: Eckfeldt
mesh_terms: D000328:Adult; D048429:Cell Size; D004906:Erythrocyte Count; D005260:Female; D005838:Genotype; D006432:Hemochromatosis / Q000235:genetics / Q000378:metabolism; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D019190:Iron Overload / Q000235:genetics / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D012015:Reference Standards; D013974:Thyroxine / Q000097:blood*; D044465:White People / Q000208:ethnology* / Q000235:genetics
chemical_list: C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D013974:Thyroxine