Preprints.org
Red Cell Phenotype Modifies the Association Between Free Triiodothyronine and the Erythron: Evidence for a Marrow Capacity Ceiling in a Thalassemia-Endemic Cohort of 3673 Adults
By Mjery YA, Abdalla SEB, Elsayed TY and 7 others.
Abstract
Background
/Objectives: Thyroid hormone regulates erythropoiesis, but most population studies have used thyrotropin (TSH) alone and could not ask whether the erythroid response depends on the marrow's capacity to respond. We examined this in a population where inherited microcytosis and iron deficiency are both common.
Methods
We analyzed 3871 adults of both sexes with paired free triiodothyronine (FT3), free thyroxine, TSH, and complete blood count from three hospitals in Jazan, Saudi Arabia (3673 with FT3 within the reference interval formed the primary analysis). All three analytes were entered simultaneously in models adjusted for age and sex; mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) were pre-specified negative controls; discriminant indices assigned red cell phenotypes, validated against linked ferritin and transferrin saturation.
