The diagnostic utility of bioelectrical impedance analysis in distinguishing precocious puberty from premature thelarche.

Objectives: Clinical (assessing breast development), laboratory (FSH, LH, estradiol, and GnRH stimulation test), and radiological methods (bone age and pelvic ultrasonography) are used to distinguish central precocious puberty (CPP) from premature thelarche (PT). We examined also via bioelectrical impedance analysis (BIA).

Methods: The fat mass (FM), fat-free mass (FFM), muscle mass (MM), bone mass (BM), total body water, and percentages (%), basal metabolic rate, phase angle (PhA), muscle-to-fat ratio (MFR), sarcopenic index, and segmental body proportions were determined via Tanita MC-780 MA model measuring device.

Results: A total of 111 girls, 34 with CPP, 35 with PT, and 42 with healthy controls, were included. Although the baseline weight, height, and BMI SDS of the groups were not statistically different, the FM (%) was found to be lower (p=0.021), and the FFM (%) (p=0.021), MM (%) (p=0.015), BM (%) (p=0.022), and MFR values (p=0.017) were higher in CPP group. In CPP group, right arm FM (%) (p=0.016), left arm FM (%) (p=0.007), and trunk FM (%) (p=0.008) were lower than other groups.

Conclusions: We detected a MFR cutoff value of (2.96) with 58.8 % sensitivity and 58.4 % specificity, a cutoff value of (3.57) with 50 % sensitivity and 82 % specificity to differentiate CPP cases from others (PT and healthy controls). These rates are relatively low, but these are the first results in this field and may be guiding for studies conducted in large series.