Rickets is a softening of the bones in children that can be caused by a vitamin D deficiency, characterized by excess of unmineralized matrix, leading to deformation of the skeleton with loss of structural rigidity. Children with rickets have an increased tendency for fractures and several skeletal deformities including flattened occipital bones, frontal bossing, rachitic rosary, and pigeon breast deformity in infants and lumbar lordosis and bowing of the legs in ambulating children.
Vitamin D deficiency can lead to excess of unmineralized bone causing loss of structural rigidity and bendy bones.
Rachitic rosary is characterized by deformation of the chest as a result from overgrowth of cartilage or osteoid tissue in the costochondral junction. It is commonly associated with rickets caused by vitamin D deficiency.
Children that are strictly breast fed are also at high risk for vitamin D deficiency because there are decreased levels in breast milk.
In adults, vitamin D deficiency leads to osteomalacia caused by derangement of normal bone remodeling processes that occur throughout life. In osteomalacia, newly formed osteoid matrix formed by osteoblasts is not properly mineralized, causing excess osteoid. This bone is weak and prone to gross fractures or microfractures, commonly seen in the vertebral bodies and femoral necks.
This is a medical sign consisting of the involuntary contraction of muscles, typically seen in the hands caused by hypocalcemia. Low blood calcium levels increase the permeability of neuronal membranes to sodium ions that cause a progressive depolarization which leads to increased possibility of action potentials.
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