Rickets is a disease of growing bone that is unique to children and adolescents. It is caused by a failure of osteoid to calcify in a growing person. Failure of osteoid to calcify in adults is called osteomalacia. The image below illustrates findings in a patient with rickets.
Findings in patients with rickets.
See 23 Hidden Clues to Diagnosing Nutritional Deficiencies, a Critical Images slideshow, to help identify clues to conditions associated with malnutrition.
Vitamin D deficiency rickets occurs when the metabolites of vitamin D are deficient. Less commonly, a dietary deficiency of calcium or phosphorus may also produce rickets. Vitamin D-3 (cholecalciferol) is formed in the skin from a derivative of cholesterol under the stimulus of ultraviolet-B light. Ultraviolet light or cod liver oil was the only significant source of vitamin D until early in the 20th century when ergosterol (vitamin D-2) was synthesized from irradiated plant steroids.
During the Industrial Revolution, rickets appeared in epidemic form in temperate zones where the pollution from factories blocked the sun’s ultraviolet rays. Thus, rickets was probably the first childhood disease caused by environmental pollution.
Natural nutritional sources of vitamin D are limited primarily to fatty, ocean-going fish. In the United States, dairy milk is fortified with vitamin D (400 IU/L) Human milk contains little vitamin D, generally less than 20-40 IU/L. Therefore, infants who are breastfed are at risk for rickets, especially those who receive no oral supplementation and those who have darkly pigmented skin, which blocks penetration of ultraviolet light.
Rickets may lead to skeletal deformity and short stature. In females, pelvic distortion from rickets may cause problems with childbirth later in life. Severe rickets has been associated with respiratory failure in children.
Findings in rickets are illustrated in the image below.
Radiograph in a 4-year-old girl with rickets depicts bowing of the legs caused by loading.