Hematological Alterations Associated with Thyroid Dysfunction Among Saudi Women: A Retrospective Cross-Sectional Comparative Study

Background: Thyroid dysfunction can affect erythropoiesis and red blood cell indices; however, reports on anemia patterns among Saudi women remain insufficient. This study investigated hematological alterations and anemia morphology in euthyroid, hypothyroid, and hyperthyroid women. Methods: A retrospective cross-sectional comparative study was conducted among 300 Saudi women at Qassim University Medical City, Saudi Arabia; 100 euthyroid, 100 hypothyroid, and 100 hyperthyroid women were included between January 2024 and January 2026. We obtained complete blood count and thyroid function data from medical records; anemia was defined as hemoglobin <12.0 g/dL and classified by mean corpuscular volume into three types. Results: Compared with euthyroid women, hypothyroid women had significantly lower hemoglobin, hematocrit, red blood cell count, and mean corpuscular volume, along with increased red cell distribution width (p < 0.05). Hyperthyroidism was associated with fewer alterations in erythrocyte indices. Anemia was present in 60 participants (20.0%) and was significantly more frequent in hypothyroidism (35.0%) than in hyperthyroidism (15.0%) or euthyroidism (10.0%; p < 0.001). Among anemic participants, microcytic anemia was most common (50.0%), followed by normocytic (45.0%) and macrocytic anemia (5.0%). Microcytic anemia was reported in 62.9% of anemic hypothyroid women; however, the morphological distribution did not differ significantly among thyroid groups (p = 0.109). Thyroid-stimulating hormone showed inverse correlations with several erythrocyte indices. Conclusions: Thyroid dysfunction, particularly hypothyroidism, was associated with anemia and altered erythrocyte indices in adult Saudi women. Complete blood count (CBC) assessment may provide additional information during thyroid disease evaluation. Further prospective multicenter studies incorporating iron, nutritional, and treatment-related variables are required to elucidate mechanisms.