Background: A child’s physical growth is fundamentally dependent on hormonal regulation, metabolism, and oxygen supply, within which bone mineralization specifically calcium (Ca²⁺) levels acts as a primary factor determining bone mineral density (BMD), muscle function, and hormonal activity. In cardiovascular disease (CVD), multiple physiological processes are disrupted at various levels, including decreased blood circulation and oxygen supply, increased energy expenditure, and reduced absorption of nutrients and micronutrients. In this context, research linking calcium levels in 6–7-year-old children with electrocardiographic (ECG) changes to physical growth has been scarce, which provided the rationale for conducting this study. Aim: To investigate the association between calcium levels and physical growth among 6–7-year-old children with electrocardiographic (ECG) abnormalities detected through early screening. Materials and Methods: This study was conducted using a case-control design. The case group included 143 children aged 6–7 with ECG changes, and the control group included 153 children without ECG changes, totaling 296 voluntary participants. Serum total calcium and albumin levels in both groups were measured using a fully automated biochemical analyzer. Statistical analysis was performed using SPSSv27, applying independent samples t-tests, ANOVA, and correlation analysis to compare means between the two groups. Results: The control group’s serum total calcium was 2.65±0.15 mmol/L, corrected calcium was 2.58±0.13 mmol/L, and the case group’s serum total calcium was 2.64±0.18 mmol/L, corrected calcium was 2.59±0.17 mmol/L, with no statistically significant difference observed between the study groups (p>0.05). When comparing total calcium in case-group children with normal height (2.66±0.20) versus those with stunted growth (2.61±0.13), a statistically significant difference was found (p<0.05). Correlation analysis between total and corrected calcium levels and physical growth indicators across study groups showed no statistically significant association. When height measurements were divided into four quartiles (Q1–Q4) and compared against total and corrected serum calcium, no statistically significant differences were found between the groups. Conclusions Comparison of physical growth and development Z-scores between children with and without ECG abnormalities revealed no statistically significant differences. However, total calcium levels tended to be lower among children with normal growth compared with those with growth retardation in the case group (p < 0.05). No statistically significant differences were observed in serum total or albumin-corrected calcium levels between the study groups (p > 0.05). When height measurements in the study groups were categorized into quartiles, no statistically significant differences in total or albumin-corrected calcium levels were observed between the groups. This suggests that calcium levels alone may not be a decisive determinant of physical growth in children of the same age.