A 4-year-old boy is brought to the physician for a well-child examination. His mother has noticed that he frequently falls while walking. He was born at term and the pregnancy was uncomplicated. He is at the 20th percentile for height and at 30th percentile for weight. Vital signs are within normal limits. Examination shows decreased muscle strength in the lower extremities. . Physical examination reveals frontal bossing, dental enamel defects, and bilateral, symmetric, bead-like enlargement of the costochondral junctions. If a histologic examination of the bone is performed, which of the following changes is most likely to be seen in this patient?

Question

A 4-year-old boy is brought to the physician for a well-child examination. His mother has noticed that he frequently falls while walking. He was born at term and the pregnancy was uncomplicated. He is at the 20th percentile for height and at 30th percentile for weight. Vital signs are within normal limits. Examination shows decreased muscle strength in the lower extremities. .  Physical examination reveals frontal bossing, dental enamel defects, and bilateral, symmetric, bead-like enlargement of the costochondral junctions.  If a histologic examination of the bone is performed, which of the following changes is most likely to be seen in this patient?

Quizplus · Accepted Answer

Eductional Objective: Vitamin D deficiency decreases intestinal absorption of calcium.  Parathyroid hormone secretion increases to maintain plasma calcium, which causes renal phosphate wasting and impaired bone mineralization.  In children, this causes rickets characterized by excessive unmineralized osteoid matrix at the epiphyseal cartilage.

A 4-Year-Old Boy Is Brought to the Physician for a Well-Child