Case history
Case history #1
A 24-month-old girl has faltering growth and an unusual gait. She has bowed legs, thick wrists, and dental caries. Her weight (17.5 lb [8 kg]) and height (28.5 in [72.5 cm]) are below the 3rd percentiles for her age. Her diet consists predominantly of breast-feeding 5 times daily. The patient was born and resides in the northeastern US with her parents after an unremarkable prenatal, delivery, and postnatal course. Laboratory studies reveal elevated total alkaline phosphatase and elevated intact parathyroid hormone level. The 25-hydroxyvitamin D level is decreased. Plain radiographs of the patient's knees and wrists demonstrate osseous changes including metaphyseal cupping and flaring, epiphyseal irregularities, and widening of the physeal plates.
Case history #2
A 13-year-old girl presents to the emergency department with 4-day history of knee pain. She cannot recall any injury to account for her symptoms. She has localized tenderness of the distal femur with no swelling, warmth, or erythema. The knee joint itself is unremarkable, with no effusion and full range of movement. Plain radiographs of the knee show generalized reduced bone density with cortical thinning, coarse trabecular pattern, and a Looser zone (pseudofracture). Blood testing shows hypocalcemia, low levels of vitamin D, elevated levels of parathyroid hormone, and high levels of alkaline phosphatase. Liver and renal chemistries are otherwise unremarkable.
Other presentations
Other presentations of rickets include hypoplasia of the dental enamel; delay in the closure of the fontanelles; parietal and frontal bossing; craniotabes (soft skull bones); rachitic rosary (enlargement of the costochondral junction, visible as beading along the anterolateral aspects of the chest); and a Harrison groove, caused by the muscular pull of the diaphragmatic attachments to the lower ribs. Hypocalcemic rickets may affect the musculoskeletal system, with decreased muscle tone, leading to delayed achievement of motor milestones, and result in predisposition to infections. Hypocalcemia may also present with carpopedal spasm, tetany, or seizures.[4][5]
Hypophosphatemic rickets has highly variable clinical characteristics and may not be diagnosed until adulthood. Adults may present with short stature, osteomalacia, bowed legs, lower leg pain, arthritis, stress fractures, dental caries, dental abscesses, and calcification of the tendons and ligaments (enthesopathy).[7]
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