Structural Thyroid Abnormalities Is Prevalent Among Rheumatoid Arthritis Patients With Normal Biochemical Thyroid Function
Main Author: Suad Hannawi
Dubai, United Arab Emirates
Emirates Health Services
Rheumatoid arthritis (RA), is a chronic incapacitating autoimmune disorder affecting multiple joints, that is associated with reduced life expectancy. The prevalence of comorbid conditions with RA varies across different countries from 3% to 60%. However, certain studies have reported a high prevalence of up to 80% of one or more comorbid conditions. Hence, this study examines the thyroid structure and morphology in clinically normal thyroid function RA patients.
RA patients were recruited through a specialized rheumatology clinic at the Ministry of Health and Prevention of UAE throughout 2019. Fasting Free thyroxine (FT4), Free triiodothyronine (FT3), thyroid stimulating hormone (TSH), thyroglobulin level, anti-thyroglobulin antibody, and anti-thyroid peroxidase antibodies (TPO) were assessed in all the participants within the same week of the thyroid ultrasound scanning.
A total of 38 RA patients satisfying ACR/EULAR criteria for diagnosis of RA and no history of thyroid disease were recruited through the main tertiary federal hospital of the Emirates Health Services (EHS), Dubai-United Arab Emirates (UAE). None of the patients had a history of renal, or hepatic disorders. None of the female patients were pregnant. The mean age for the participants was 50 ± 14 (range 21 – 87) years. The mean level of free thyroxine (FT4) was 15.67 ± 2.57 (range:8.92 – 21.89) (NR: 12-22 pmol/L), free triiodothyronine (FT3) was 4.35 ± 0.76 (range 2.60-5.57) (NR: 4-6.8 pmol/L), thyroid-stimulating hormone (TSH) was 2.55 ± 1.69 (range: 0.09 – 7.18) (NR:0.27-4.2 mlU/L), antithyroglobulin was 185.35 ± 272 (range: 11 – 986), thyroglobulin was 98.58 ± 172.67 (range: 2.4 – 405.4) and mean anti-thyroid peroxidase antibody (TPO Abs) was 16.03 ± 12.05 U/mL (range: 5 -44.5, NR: < 60 U/mL), Table.1
Thyroid ultrasound scanning showed the following structural changes; Right lobe: 8 (21%) of the participants had one right lobe nodule and 7 (18%) had 3 or more nodules. The mean size of the nodules ranged from 3.53 (±11.26) to 3.88 (±12.54) mm. Out of the right lobe nodules, 6 (40 %) were complex,
8 (53%) were solid and 1 (7%) were cystic nodules. In 12 (80%) of the nodules, the borders were definite and in 3(20%) it was irregular borders. 4 (10%) of the patients had heterogenous right lobe echotexture and 34 (90%) had homogenous echotexture, and 5 (13%) exhibited hypervascularity. There was macrocalcification in 1 (3%), and there was no microcalcification or cervical lymph node enlargement. Table. 2
In the left lobe: 7 (18%) of the patients had one left lobe nodule and 6 (16%) had 3 or more nodules. The mean size of the nodules ranged from 0.57 (± 1.27) to 1.39 (± 4.096) mm. In 2 (15%) of the participants the nodules were Complex, in 2 (15%) were cystic, and in 9 (70%) were solid. In 11 (85%) of the patients, the nodules had definite borders and in 2 (5%) the nodules had irregular borders. 6 (16%) of the patients had heterogenous left lobe echotexture and 32 (84%) had homogenous echotexture. 6 (16 %) of the patients exhibited hypervascularity. There was macrocalcification in 5 (13%), 1 (3%) had microcalcification, and none had cervical lymph node enlargement. Table. 2
Thyroid structural abnormalities are prevalent among clinically and laboratory-normal RA patients. Structural changes may precede clinical abnormalities. Further studies at a larger scale are needed to confirm our current study findings.