Prospective case-control study of children (3-15 years) after low-energy trauma. We compare serum bone metabolic markers (25OHD, PTH, ALP, calcium, phosphate), BMI/percentile, and dietary calcium intake between fracture and non-fracture presentations. Blood is collected within 7 days (non-fasting; samples on ice for PTH). Primary aim: association of ALP and calcium with fracture status; secondary aims: vitamin D status, BMI percentile, and a composite Bone Risk Score (≥3). Analyses: group comparisons, logistic regression, ROC.

Low-energy fractures in children are a common cause of morbidity and may reflect underlying skeletal fragility. Emerging evidence suggests that hypovitaminosis D, obesity, and abnormal bone metabolism play important roles in fracture risk. However, the combined effect of these factors remains insufficiently studied, particularly in pediatric populations.

This study is designed as a prospective case-control investigation to explore the relationship between vitamin D status, bone metabolic markers, and obesity in children presenting with trauma. Children aged 3-15 years with low-energy trauma will be recruited and divided into two groups: those with radiologically confirmed fractures (cases) and those with similar trauma but without fractures (controls).

Baseline assessments include anthropometric measurements, dietary calcium intake through a food-frequency questionnaire, and laboratory evaluation of bone metabolism. Blood samples will be obtained within 7 days of the trauma and processed under standardized conditions to measure 25-hydroxyvitamin D (25OHD), parathyroid hormone (PTH), alkaline phosphatase (ALP), calcium, and phosphate. Samples are collected non-fasting and stored on ice to minimize variability in PTH measurement.

The primary outcome is the association of fracture occurrence with serum alkaline phosphatase (ALP) levels. Secondary outcomes include serum calcium, 25OHD concentration, a composite bone risk score, and body mass index (BMI) percentile. Outcomes are analyzed using descriptive statistics, group comparisons, and logistic regression to identify independent predictors of fracture risk.

The study aims to provide novel insights into the multifactorial etiology of pediatric fractures. By integrating metabolic, nutritional, and anthropometric data, the project seeks to establish a more comprehensive risk profile that can guide preventive strategies and inform clinical practice in pediatric bone health.

Inclusion Criteria:

• 3-15 years;
• low-energy trauma;
• cases = radiographic fracture; controls = no fracture.

Exclusion Criteria:

• chronic renal/liver disease;
• primary hypo-/hyperparathyroidism;
• hypophosphatemic rickets;
• neuromuscular disorders;
• corticosteroids/bisphosphonates;
• unclear diagnosis/treatment.

Children and adolescents aged 3 to 15 years presenting to emergency services after low-energy trauma. Eligible participants include those with radiologically confirmed fractures (case group) and those with comparable trauma without fractures (control group). All participants are otherwise healthy and free from chronic conditions or treatments that may influence bone metabolism.