{
 "topic": "Rickets",
 "slug": "rickets",
 "category_id": 14938,
 "summary": "Defective mineralization of growing bone, most often from vitamin D deficiency, producing characteristic skeletal deformity and fracture risk in infants and children.",
 "written_by": "claude-sonnet",
 "references": [
  {
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  },
  {
   "title": "CURRENT Diagnosis and Treatment Pediatrics, Twenty-Fourth Edition",
   "author": "Hay, William W., Levin, Myron J., Deterding, Robin R., Abzug, Mark J.",
   "pages": [
    1067
   ]
  }
 ],
 "short": [
  {
   "title": "In short",
   "content": "- Rickets is defective mineralization of growing bone leading to bony deformity; vitamin D deficiency is the most common cause, but calcium deficiency, phosphorus deficiency, and distal renal tubular acidosis also cause it.\n- Calcium-deficiency rickets can occur after weaning from breast milk or formula when dietary calcium is under 200 mg/day (age under 12 months) or under 300 mg/day (over 12 months), and is worsened by phytate-, oxalate-, and phosphate-rich grain/vegetable diets that block calcium absorption.\n- Classic skeletal findings: craniotabes, frontal bossing, delayed fontanel closure (normally closed by 2 years), rachitic rosary, Harrison groove, widened wrists and ankles, genu varum/valgum, windswept deformity, and anterior bowing of the tibia/femur.\n- Dental findings: no incisors by 10 months, no molars by 18 months, delayed dental eruption, and enamel hypoplasia/defects.\n- Hypocalcemic features can include tetany, seizures, laryngeal-spasm stridor, and hypocalcemic dilated cardiomyopathy.\n- Radiographic diagnosis shows cupping, splaying, and fraying of the metaphyses, bowing of long bones, cortical narrowing, stress fracture lines, and diffuse demineralization.\n- Preterm and low-birth-weight infants (especially under 27 weeks gestation or under 1500 g) are at higher risk because maternal-fetal calcium/phosphorus transfer peaks in the third trimester; rickets of prematurity typically occurs 1-4 months after birth and can cause nontraumatic rib, arm, and leg fractures with respiratory distress from chest wall softening after 5 weeks of age.\n- The American Academy of Pediatrics (2008) recommends vitamin D supplementation of at least 400 IU/day for breastfed infants because of high rates of occult vitamin D deficiency.\n- Rickets causes secondary hyperparathyroidism in most forms, the exception being hypophosphatemic rickets (e.g., familial hypophosphatemic rickets, from abnormal renal phosphate handling related to FGF23 regulation)."
  }
 ],
 "long": [
  {
   "title": "Definition",
   "content": "Rickets is defective mineralization of growing bone that results in bony deformities, principally caused by vitamin D deficiency. It describes a characteristic set of clinical and radiologic bony features, most often associated with a defect in calcium, phosphorus, or vitamin D metabolism."
  },
  {
   "title": "Etiology",
   "content": "Vitamin D deficiency, from inadequate sunlight exposure or dietary intake, is the most common cause of rickets worldwide. Although largely corrected in many countries through public health measures ensuring adequate vitamin D, it persists in developed countries among children on restrictive diets (e.g., for autism) or elimination diets (e.g., for feared allergies), and remains a significant problem in developing countries. Other causes include primary calcium deficiency, phosphorus deficiency, and distal renal tubular acidosis. Calcium-deficiency rickets is a particular problem in parts of Africa but also occurs in industrialized countries; it typically develops after weaning from breast milk or formula (which are good calcium sources), especially with early weaning, when dietary calcium falls below about 200 mg/day under 12 months of age or 300 mg/day over 12 months, compounded by grain- and vegetable-heavy diets high in phytate, oxalate, and phosphate that impair calcium absorption. Children with milk allergy or those transitioning off dairy are also at risk. Familial hypophosphatemic rickets results from abnormal renal phosphate wasting related to dysregulated fibroblast growth factor 23 (FGF23)."
  },
  {
   "title": "Clinical features",
   "content": "General findings include failure to thrive, listlessness, a protruding abdomen, proximal muscle weakness, hypotonia, lethargy, hypocalcemic dilated cardiomyopathy, pathologic fractures from minimal trauma, and increased intracranial pressure. Head findings include craniotabes, frontal bossing, delayed fontanel closure (normally closed by 2 years), delayed dentition (no incisors by 10 months, no molars by 18 months), caries, and craniosynostosis. Chest findings include rachitic rosary and Harrison groove, with associated respiratory infections and atelectasis. Back findings include scoliosis, kyphosis, and lordosis. Extremity findings include enlargement of the wrists and ankles, valgus or varus deformities, windswept deformity, anterior bowing of the tibia and femur, coxa vara, and leg pain. Hypocalcemic symptoms include tetany, seizures, and laryngeal-spasm stridor. Presentation depends on the underlying disorder, duration, and the child's age: craniotabes reflects the skull's rapid perinatal growth, rachitic rosary and wrist flaring reflect rapid upper-limb and rib growth in the first year, and leg bowing is not seen until the child is ambulatory."
  },
  {
   "title": "Diagnostics",
   "content": "Diagnosis rests on classic radiographic abnormalities \u2014 cupping, splaying, and fraying of the metaphyses of long bones, bowing, cortical narrowing, stress fracture lines, and diffuse demineralization \u2014 supported by physical examination, history, and laboratory findings consistent with a specific cause. Because most children with rickets have a nutritional deficiency, initial evaluation should focus on dietary history; family history can help identify 1-alpha-hydroxylase deficiency or renal phosphate wasting, and a history of prior vitamin D treatment and response can help localize the underlying defect. Laboratory severity grading uses calcium, phosphorus, and vitamin D levels, ranging from mild (normal-to-low calcium, normal-to-low phosphorus) to severe (low calcium, low phosphorus, very low vitamin D); 25-hydroxylase deficiency shows normal calcium with low phosphorus. All patients with rickets have an abnormality of calcium and/or phosphorus."
  },
  {
   "title": "Differential diagnosis",
   "content": "Rickets should be considered in any child with nonspecific bony complaints, bowed legs, limb pain and swelling, seizures, failure to thrive, hypocalcemia, or an unusual fracture pattern. A similar clinical appearance can occur with renal tubular disorders, chronic liver disease, and various metabolic disorders, which biochemical evaluation can distinguish from nutritional vitamin D or calcium deficiency."
  },
  {
   "title": "Prevention",
   "content": "Because of high rates of occult vitamin D deficiency, the American Academy of Pediatrics recommends in 2008 that breastfed infants receive vitamin D supplementation of at least 400 IU/day. In infants at high risk for rickets of prematurity, at least one screening radiograph is appropriate at 6-8 weeks of age, with additional films as indicated, alongside weekly monitoring of calcium, phosphorus, and alkaline phosphatase and periodic serum bicarbonate measurement, since metabolic acidosis promotes bone dissolution."
  },
  {
   "title": "Complications",
   "content": "Rickets of prematurity occurs 1-4 months after birth in preterm or low-birth-weight infants (particularly under 27 weeks gestation or under 1500 g), because unsupplemented breast milk and standard formula do not supply enough calcium and phosphorus for a premature infant's needs; other risk factors include cholestatic jaundice, a complicated neonatal course, prolonged parenteral nutrition, soy formula, and diuretics or corticosteroids. Affected infants can sustain nontraumatic fractures of the legs, arms, and ribs, often clinically unsuspected, and rib/chest softening can cause rachitic respiratory distress from atelectasis, typically appearing more than 5 weeks after birth (distinguishing it from early-onset prematurity-related respiratory disease). Long-term effects include poor linear growth persisting beyond 1 year, enamel hypoplasia, and dolichocephaly from poor bone mineralization. Most infants with rickets of prematurity have no clinical manifestations, and diagnosis rests on radiographic and laboratory findings alone."
  }
 ],
 "clinical": [
  {
   "title": "Bedside evaluation",
   "content": "In a child with bony deformity, fracture out of proportion to trauma, failure to thrive, or nonspecific bone pain, start with a dietary and social history, since most rickets is nutritional; a family history can suggest 1-alpha-hydroxylase deficiency or renal phosphate wasting, and prior response to vitamin D treatment can help localize the defect. Examine for craniotabes, frontal bossing, delayed fontanel closure, rachitic rosary, Harrison groove, and widened wrists and ankles, and check for hypocalcemic signs \u2014 tetany, seizures, or stridor from laryngeal spasm. Confirm with radiographs showing metaphyseal cupping, splaying, and fraying, bowing, cortical narrowing, or stress fracture lines, alongside laboratory testing of calcium, phosphorus, and vitamin D levels, since all patients with rickets have an abnormality in calcium and/or phosphorus."
  },
  {
   "title": "Monitoring high-risk infants",
   "content": "In preterm or low-birth-weight infants, particularly those under 27 weeks gestation or under 1500 g, monitor calcium, phosphorus, and alkaline phosphatase weekly and check serum bicarbonate periodically, since metabolic acidosis promotes bone dissolution. Obtain at least one screening radiograph for rickets at 6-8 weeks of age in high-risk infants, with additional films as clinically indicated. For prevention, ensure breastfed infants receive vitamin D supplementation of at least 400 IU/day, per the American Academy of Pediatrics recommendation."
  }
 ]
}