Thyroid ultrasound findings associated with thyroid peroxidase autoantibody positivity in patients with diffuse goiter

ABSTRACT

BACKGROUND: To determine the thyroid ultrasound findings in association with anti-TPO positivity among patients with diffuse goiter.DESIGN AND METHODS: We performed a cross-sectional study on patients with diffuse goiter seen at Makati Medical Center out-patient Endocrine clinics from October 1, 2011 to October 1, 2012. Patients with anti-TPO (thyroid peroxidase) above 100 pmol/L were considered anti-TPO positive and below this level were considered negative. After excluding patients with other possible causes of thyroiditis, thyroid ultrasound of anti-TPO positive and anti-TPO negative patients were reviewed and compared based on size, echogenicity, echopattern and vascularity of the thyroid parenchyma.RESULTS: In 94 patients who qualified for the study, 43.6% were anti-TPO positive. A higher proportion of anti-TPO positive was seen among females compared to males by almost twofold (49.7% vs 25%, p0.05). Stratified according to age group for female patients, anti-TPO positivity is relatively higher among 31-50 years old (51.1%, p =0.753). Among male, anti-TPO positivity is present in all 18-2 years old which is significantly higher compared to other age group (p larger thyroid size in all measurement parameters (p= 0.0053). Among anti-TPO positive patients, frequent ultrasound findings were hypoechoic (79% vs. 21%, p 0.001); heterogenous parenchyma (71% vs. 29%, p 0.001) and increased vascularity (93% vs. 7%, p 0.001). Of note is the absence of homogenous prenchyma fnding among anti-TPO positive. All 23 (100%) patients who showed combined findings of hypoechoic, heterogenous parenchyma and increased vascularity were anti-TPO positive.CONCLUSION: Thyroid ultrasound findings that are found frequently among anti-TPO positive are increased thyroid size, parenchyma that are hypoechoiec and heterogenous and increased vascularity. Homogenous echotexture was not seen among anti-TPO positive. The combined sonographic characteristics of hypoechoic, heterogenous pattern and increased vascularity are highly suggestive of presence of anti-TPO (100%).