Obesity is caused by fat accumulation. BMI Z-score is used to classify the different degrees of weight status in children and adolescents. However, this parameter does not always express the true percentage of body fat. Our objective was to determine the degree of agreement between the fat mass percentage measured by DXA and the stratification of weight according to BMI Z-score in the pediatric age group. We designed a descriptive cross-sectional study. The patients were classified as underweight/normal weight with Z-scores between −2 and +0.99, overweight from 1 to 1.99, obese from 2 to 2.99, and very obese ≥3. We included 551 patients (47% girls), with a mean age of 11.5 ± 2.8 years (3.7–18 years). Higher BMI Z-scores were associated with a higher percentage of total fat (p < 0.001). However, there were important overlaps between both parameters, such that the BMI Z-score classified patients with the same percentage of total fat mass as having a different nutritional status classification. In conclusion, the stratification of weight status according to BMI Z-score revealed that 46.7% of patients had a fat percentage that did not correspond to their classification. For a more accurate weight assessment in clinical practice, we recommend combining anthropometric indices with diagnostic tools that better correlate with DXA, such as electrical bioimpedance.

Hashimoto's thyroiditis is the most common cause of goiter and hypothyroidism among children and adolescents. Its clinical manifestations and course vary. The objective of this study was to review the clinical and evolutionary characteristics of Hashimoto's disease in the pediatric population. Clinical, analytical, ultrasound, epidemiological, and evolutionary data of patients with autoimmune thyroiditis seen at Hospital Universitario San Juan de Alicante between January 2010 and January 2016 were analyzed. A total of 29 patients were included in the study. A higher prevalence of girls was observed, at a 2: 1 ratio. The main reason for consultation was the accidental detection of high thyroid stimulating hormone levels or positive anti-thyroid antibodies in a lab test done for other reason. In the initial analysis, 53.3% of patients had subclinical hypothyroidism and only 10% of them had frank hypothyroidism. Two patients developed thyroid cancer.