Assessment of Red Cell Distribution Width among Sudanese Patients with Subclinical Hypothyroidism

Background: Thyroid dysfunction has a strong association with anemia. Red blood cell distribution width (RDW) was traditionally regarded as a part of the routine evaluation of anemia. Several studies have indicated that elevated RDW level is significantly associated with subclinical hypothyroidism and hypothyroidism. The present study aimed to assess the impact of subclinical hypothyroidism (SHT) on RDW in Sudanese patients. Methods and Results: The study was designed as a case-control, laboratory-based study carried out at the National Cancer Institute – University of Gezira (NCI-UG) (Wad Medani, Gezira State, Sudan) from January to October 2020.The samples were collected randomly from 100 subjects: 50 patients (mean age 38.50±10.46 years; 36% males and 64% females) with hypothyroidism (case group) and 50 apparently healthy individuals (mean age 35.52±11.64 years; 46% males and 54% females) (control group). The case group was divided into 2 subgroups: Sub1 included 43(86%) patients with SHT grade 1 (TSH of 6-10μIU/mL), and Sub2 included 7(14%) patients with SHT grade 2 (TSH>10μIU/mL). A 3ml venous blood sample was collected in an EDTA container from each participant. The parameters of the RBCs (RBC count, MCV, RDW-CV, and RDW-SD) were measured using the Sysmex XP-300 Automated Hematology Analyzer. In the case group, the average levels of RDW-SD, RDW-CV, and MCV were higher than in the control group (P=0.000 in all cases). There was a significant difference in RDW-CV between Sub1 and Sub2 (P=0.040). We found no significant differences in RDW-SD and RDW-CV between different age groups. There was a significant difference in RBC count between different age groups (P=0.022), and significant differences in RBC count and MCV between males and females. RDW-SD and RDW-CV had a significant positive correlation within TSH and a significant negative correlation within T3 and T4. Conclusion: RDW-CV may be used as a marker of SHT grade 2.