When calcium deficiency occurs in 12-year-old children, it may cause calf cramps and muscle twitches, which can be especially noticeable at night. Spasmodic pain in the calves can occur at night, and children may have difficulty sleeping because of crampy calf pain. It can also cause pain around the joints, mainly because children have an increased need for calcium ions during growth and development, and because calcium deficiency can cause increased neuromuscular excitability, causing joint pain. If there is a prolonged calcium deficiency in infants and young children, it can cause deformities in the knee joints, such as inversion and valgus of the knee, as well as changes in the rib cage and deformed chest.