What is the earliest sign of rickets in children?

The earliest sign of rickets in children is often the presence of a soft skull. Rickets is primarily caused by a deficiency in vitamin D, calcium, or phosphate, which is essential for bone mineralization. In infants, one of the earliest areas to exhibit signs of abnormal mineralization is the skull. The softening of the skull occurs due to the failure of bone turnover processes to effectively mineralize the rapidly growing cranial bones. As a result, the skull may become soft and pliable, leading to a condition known as "craniotabes," which is characterized by areas of thinning in the skull's outer layers.

While curved spine, bowed legs, and swollen joints can present later as the deficiency worsens and more severe skeletal deformities develop, the softening of the skull is typically one of the first signs noted in infants who are developing rickets. Therefore, recognizing this early sign is crucial for timely intervention and prevention of more advanced complications associated with rickets.