LAUSR

INTRODUCTION The reference values for thyroid volume (TV) suggested by the WHO are recommended for children aged 6 to 12 years and cannot be considered relevant for infants. The present study aimed to establish the normal values for TV and thyroid isthmus depth (TID) in infants aged between 1 and 12 months from the west coast of Turkey. MATERIAL AND METHODS The TV and TID were measured in 223 infants by a validated ultrasound technique. The TV was determined by the method of Brunn et al. and Brown et al. The 3rd, 25th, 50th, 75th, and 97th percentiles of the TV and TID according to age were produced. The TV and TID measurements were compared with infants' age, gender, and standard deviation (Z) scores for weight, height, and BMI. RESULTS The median (IQR) values for TV were 0.77 (0.61-1.00) and 0.84 (0.67-1.10) mL, calculated according to the formula of Brunn et al. and Brown et al., respectively. The TV was significantly associated with age, and Z scores for weight, height, and body mass index (BMI) (r = 0.366, p < 0.001; r = 0.343, p < 0.0001; r = 0.269, p < 0.0001; and r = 0.157, p = 0.019; respectively). The median (IQR) value for the TID was 1.5 (1.3-1.9) mm. The TID was significantly correlated with TV and the Z score for height (r = 0.190, p = 0.004; and r = 0.144, p = 0.032; respectively). In multivariable regression, the only independent predictor for TV was the Z score for BMI. No differences based on gender were found. CONCLUSIONS This is the first study to report the normative values for TV and TID in healthy Turkish infants aged up to 12 months. Our findings may serve as a basis for developing national and international references for TV and TID in infants.