A hypoechoic pattern of the thyroid at ultrasound does not indicate autoimmune thyroid diseases in patients with morbid obesity.
OBJECTIVE
Thyroid ultrasound (US) scan is a valuable tool for diagnosing thyroid diseases. In autoimmune thyroid disease (AITD), an hypoechoic pattern of the thyroid at US is related to circulating thyroid antibodies (Abs). The aim of this study was to evaluate the diagnostic accuracy of thyroid US for the detection of AITD in patients with morbid obesity.


METHODS
Thyroid US scans showing an hypoechoic pattern of the thyroid were collected from 105 morbid obese patients (body mass index (BMI) >40 kg/m(2)) and 105 non-obese patients (BMI<or=30 kg/m(2)).


RESULTS
A thyroid hypoechoic pattern at US was consistent with clinical/biochemical features of AITD in 90/105 (85.7%) non-obese patients and in 22/105 (20.9%) morbid-obese patients (P<0.0001). By performing a complete thyroid work-up, including clinical examination, thyroid morphology, serum hormones, and auto-Ab measurements, the discrepancy between the US pattern and the results of the thyroid Ab tests was justified in 6/15 non-obese patients, and only in 1/83 morbid obese patients. Thus, an unexplained hypoechoic pattern of the thyroid at US, defined as negative tests for thyroid Ab and absence of justifying thyroid disturbances, was found in 2/105 (1.9%) non-obese patients and in 68/105 (64.8%) morbid obese patients (P<0.0001).


CONCLUSIONS
Our results suggest that i) morbid obesity may affect thyroid morphology, and ii) an hypoechoic pattern of the thyroid at US, a well-established parameter for diagnosing AITD, has a poor diagnostic accuracy when patients with morbid obesity are taken into account.
Rotondi
Mario
M
Unit of Internal Medicine and Endocrinology, Fondazione Salvatore Maugeri IRCCS, ISPESL Laboratory for Endocrine Disruptors, University of Pavia, Via S Maugeri 10, I-27100 Pavia, Italy.
Cappelli
Carlo
C
Leporati
Paola
P
Chytiris
Spyridon
S
Zerbini
Francesca
F
Fonte
Rodolfo
R
Magri
Flavia
F
Castellano
Maurizio
M
Chiovato
Luca
L
D000328:Adult; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000000981:diagnostic imaging*; D013959:Thyroid Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging*; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D014463:Ultrasonography