A 1-year-old African American infant is in for well-child care. He is primarily breast-fed. His parents do not give him much solid food because he has no teeth. He receives no medications or supplements. His parents are concerned about his bowed legs. On examination, you note some other bony abnormalities including frontal bossing, enlargement of the costochondral junctions, a protuberant sternum (pigeon chest), and severe bowing of the legs. You obtain x-rays to confirm your clinical diagnosis and also note a healing fracture of the left femur.
Which of the following is the most likely diagnosis?
- osteogenesis imperfecta
- scurvy
- congenital syphilis
- rickets
- chondrodystrophy
Answer(s): D
Explanation:
Babies who are exclusively breast-fed for prolonged periods of time are at risk for developing rickets. Dark- skinned infants are at high risk, especially during winter months when they receive inadequate sunlight.
Supplementation with vitamin D is recommended in children who are at high risk, as well as pregnant and lactating mothers. Clinical features include craniotabes, a thinning of the outer table of the skull. This may also occur in osteogenesis imperfecta. Enlargement of the costochondral junctions rachitic rosary) may be seen in rickets, scurvy, and chondrodystrophy. Other features may include delayed primary teeth, enamel defects, and caries. There may be thickening of the wrists and ankles; bending of the femur, tibia, and fibula result in bowlegs or knock-knees. Greenstick fractures of long bones may occur without symptoms.
Diagnosis is based on history of inadequate vitamin D intake and clinical features. Diagnosis may be confirmed by x-rays and chemistry; serum calcium is low or normal, serum phosphorus is low, serum alkaline phosphatase is elevated, and serum 25- hydroxycholecalciferol is decreased. Breast milk contains adequate vitamin C as long as the mother is not deficient.