Rickets is caused by a deficiency of what? For rickets, its main gold standard for diagnosis is based on the results of blood biochemistry and skeletal X-ray examinations. Generally, the deficiency in rickets is mainly due to insufficient levels of vitamin D, which then leads to disturbances in calcium and phosphorus metabolism. Typically, this is characterized by low levels of 25-hydroxyvitamin D3 in the body, along with decreased levels of blood calcium and phosphorus, manifesting as deficiencies in calcium, phosphorus, and vitamin D. However, in children, rickets could also be caused by other factors, such as abnormalities in liver or kidney function, or congenital hereditary diseases. Generally, further tests are needed to confirm rickets. If other special causes are ruled out, timely supplementation of vitamin D and appropriate exposure to sunlight, along with calcium supplementation, can effectively cure the disease.