Introduction:

Subclinical hypothyroidism (SH) is a biochemical diagnosis made when a serum thyroid-stimulating hormone (TSH) is ele-vated with circulating thyroid hormone levels within their reference ranges.

Aim of the study:

Aim of our prospective non-randomized study was to evaluate the course of SH.

Material and methods:

All patients with suspicion of SH referred to the Endocrinology Outpatient Clinic between 2014 and 2018 were recruited to prospective study.

Results:

A total of 130 patients with SH were recruited for this study. Thirty-five (26.9%) patients were followed up without levothy-roxine (L-T4) (SH-T0 group) and therapy with L-T4 was randomly introduced in 95/130 (73.1%) SH children (SH-T1 group). We did not find statistical differences in hSDS and BMI Z-score between the SH-T0 and SH-T1 groups (p = 0.761 and p = 0.843, respectively). Introducing L-T4 in patients with short stature did not affect the linear growth at the end of FU ex-pressed as hSDS. OH developed in six children (6.3%) in the SH-T1 group. After conducting a multivariate logistic regres-sion, we found that the baseline TSH concentration and BMI Z-score are possible predictors of OH.

Conslusions:

Our study confirmed a low risk of progression of SH to overt hypothyroidism. The majority of patients remains SH or resolved for nor-mal thyroid function. The L-T4 therapy did not effect on linear growth and body weight. The main predictor of worsening to hypothyroidism were a higher TSH level and Z-score BMI.