Rickets (from Greek rhahis – spine) is a disease of young children in which, due to vitamin D deficiency, calcium-phosphorus metabolism, bone formation and mineralization processes, as well as nervous system and internal organ functions, are affected.

Prevalence
“Classic” rickets remains a fairly common disease. It affects infants during periods of rapid growth between 2 months and 2 years, with an incidence of 10–35%.

Etiology
Rickets in young children is caused by insufficient intake of vitamin D.

Vitamin D
The term “vitamin D” refers to a group of substances including over 10 structural analogs with antirachitic properties and varying activity. The main forms are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).

Sources of Vitamin D

  • Vitamin D2 is obtained from purple corn mouse (fungus), found in small amounts in vegetable oil, margarine, and wheat germ.
  • Vitamin D3 is found in cod liver oil, tuna, and egg yolk.
    Vitamin D mainly enters the body in the form of precursors.

Role of diet
Diet is important for vitamin D intake, especially when endogenous synthesis is impaired. Intake of cholecalciferol from animal products is essential.

Physiological needs for vitamin D
Daily diet contains little vitamin D, which is rare in nature. According to WHO, recommended doses are:

  • Adults – 100 IU
  • Children – 400 IU
  • Pregnant or breastfeeding women – 1000 IU

Regulation of calcium metabolism
The main function of vitamin D and its metabolites is maintaining calcium and phosphorus homeostasis, necessary for normal bone tissue maturation and metabolic processes. Deficiency of calcium, phosphorus, magnesium, copper, zinc, iron, cobalt, proteins, and amino acids can disrupt phosphate-calcium metabolism and cause clinical rickets. Calcium intake is regulated by the parathyroid glands, which secrete parathormone and calcitonin, together with vitamin D.

Pathogenesis
The disease is favored by anatomical and physiological characteristics of young children: rapid growth requiring building materials, active metabolism, and bone structure composed of easily soluble calcium-phosphate, making rickets common.

Predisposing factors
Many perinatal factors (maternal diseases during pregnancy, gestosis, birth complications) predispose to rickets. Calcium and phosphorus are transferred intensively during the last months of pregnancy, so children born before 30 weeks often have osteopenia. Maternal diet and lifestyle also contribute. Immaturity and liver, kidney, or skin diseases favor rickets, especially in premature infants. Proper nutrition for osteogenesis requires proteins, calcium, phosphorus, magnesium, zinc, vitamins B and A. Lack of physical activity reduces bone vascularization and contributes to rickets.

Main mechanisms
Vitamin D deficiency occurs due to insufficient intake or reduced endogenous synthesis (low sun exposure). Risk increases in winter due to inadequate sunlight. Vitamin D deficiency reduces calcium and phosphorus absorption, leading to bone demineralization.

Clinical picture
Currently, mild and subacute forms predominate, complicating diagnosis. Early diagnosis of vitamin D deficiency is difficult and uses indirect methods—measuring calcium, phosphorus, and alkaline phosphatase in blood.

Initial period
In children under one year, neurological and muscular changes appear: irritability, agitation, exaggerated reflexes to noise and light, restless sleep, sweating (especially on the head), and hair loss in the occipital area. After 2–3 weeks, softening of bone edges at the large fontanelle and cranial sutures is observed. Muscle tone decreases. Blood calcium is normal, phosphorus slightly low. Phosphaturia appears in urine.

Crisis period
Neurological and muscular symptoms worsen: sweating, weakness, muscle and ligament hypotonia, psychomotor delay. Bone changes intensify: softening of flat cranial bones (craniotabes), occipital flattening, formation of frontal and occipital prominences giving the head a square or “bow-shaped” form. Facial deformities may occur (crooked nose, prominent forehead), delayed or affected dentition (caries). The chest deforms (rachitic margins, pigeon chest, kyphosis, lordosis, scoliosis). Deep grooves (Harrison’s sulcus) appear on the chest. The lower edge of the thorax protrudes forward.

Convalescence period
Active symptoms disappear, general condition improves, blood calcium and phosphorus normalize (calcium may remain low due to intense bone deposition). This period lasts 6 months to 2 years.

Sequelae period
Rickets signs weaken as growth slows. After 2–3 years, bone deformities may persist in the spine and limbs. Biochemical changes disappear, and bone remineralization is slow. Radiologically, growth points appear and enlarge, cortical and periosteal layers thicken.

Severity

  • Mild rickets: diagnosed based on initial signs.
  • Moderate rickets: moderate bone and organ changes.
  • Severe rickets: pronounced bone deformities, neurological involvement, anemia, delayed development. Complications can include secondary infections, tetany, convulsions, heart failure, laryngospasm, hypocalcemia, and even sudden death.

Main clinical signs

  • Head: craniotabes, persistent large fontanelles, delayed dentition.
  • Chest: “Rachitic margins” at rib-sternum junction, chest deformities.
  • Spine: loss of normal curvatures and appearance of pathological curvatures (kyphosis, lordosis, scoliosis).
  • Limbs: swelling at epiphyses, hip and lower limb joint deformities (O/X-shaped legs, flat rachitic pelvis).

Associated symptoms
Muscle weakness, hypotonia, decreased activity, prominent abdomen with hernia risk, frequent respiratory infections, iron-deficiency anemia. Cardiac, pulmonary, and neuropsychological changes may also occur.

Radiology
Osteoporosis, especially in epiphyses and tubular bones, delayed bone point development, periosteal thickening, diaphyseal changes.

Rickets in newborns and preterm infants
Appears early, predominantly bone changes with mild neurological symptoms. Craniotabes, large fontanelles, open sutures, and low biochemical parameters (phosphorus and calcium) depending on gestational age. Bone ultrasound aids diagnosis.

Drug-induced rickets
Medications such as phenobarbital, phenytoin, and other anticonvulsants reduce vitamin D levels, causing hypocalcemia, convulsions, and bone fractures. Glucocorticoids affect calcium absorption and may lead to osteoporosis. Heparin increases collagenolytic activity and prevents calcium deposition in bones. Other drugs (furosemide, sodium bicarbonate, aluminum-containing antacids) can favor rickets. These situations require careful pediatric supervision.

Treatment
Treatment aims to correct vitamin D deficiency, normalize phosphate-calcium metabolism, eliminate acidosis, and stimulate bone formation, along with general supportive measures. Rickets treatment and prevention must be conducted under strict pediatric medical supervision.