Rickets

Disease Description (Causes and Symptoms)

Disease name: Rickets (Rickets)

• Causes and pathophysiology

  • The main cause is an abnormality in calcium and phosphorus metabolism due to vitamin D deficiency. Vitamin D deficiency reduces calcium absorption in the intestines, which can lower blood calcium levels or disrupt phosphorus metabolism and interfere with the ossification (calcification) of cartilage at the growth plates.
  • It can also occur due to abnormalities in vitamin D metabolism (hereditary vitamin D–dependent rickets), kidney disease (renal osteodystrophy), malabsorption of food (fat malabsorption), and other causes.

• Main symptoms

  • Occurs mainly in growing children: leg deformities (bowed legs or knock-knees), bone pain and abnormal gait due to osteomalacia
  • Chest deformities (pigeon chest, funnel chest), costochondral thickening (bead-like appearance), skull softening (depression of the skull in infants), and increased risk of fractures
  • Systemic symptoms: excessive sweating (especially of the scalp), pallor, decreased muscle strength, and abdominal distension
  • In severe cases, hypocalcemia may cause seizures (clonic seizures)

• Diagnostic findings

  • X-ray: widening, cupping, and fraying of the growth plate area (changes in the epiphyseal line)
  • Blood tests: low (or normal) calcium, low phosphate (in nutritional rickets), elevated alkaline phosphatase (ALP), and low 25‑OH vitamin D
  • Additional tests: whether PTH is elevated, urine calcium, and, if necessary, genetic testing (to differentiate vitamin D–dependent or hypophosphatemic rickets)

Treatment Methods

• General principles

  • Correct the cause of the deficiency (vitamin D and calcium supplementation), treat underlying diseases (such as malabsorption and kidney disease), and provide orthopedic correction when necessary

• Drug treatment

  • Vitamin D supplementation: for nutritional rickets, with the goal of correcting 25‑OH vitamin D deficiency
    • The standard dose varies depending on age and severity; representative examples include:
      • Prevention (breastfed infants): vitamin D3 400 IU/day
      • Treatment (mild to moderate cases, children): vitamin D3 1,000–2,000 IU/day or high-dose treatment as directed by a doctor (e.g., 2,000–6,000 IU/day for several weeks or a single high-dose Stoss regimen) — a doctor's prescription and monitoring are essential
    • In hereditary or special forms (e.g., vitamin D–dependent rickets), use of active vitamin D (alfacalcidol, calcitriol) is necessary
  • Calcium supplementation: dietary intake/oral supplementation with the goal of reaching the age-specific recommended daily calcium intake (temporary high-dose supplementation in severe cases)
  • In cases of complications (such as hypocalcemic seizures), emergency treatment including hospitalization and intravenous calcium administration

• Non-drug treatment and management

  • Regular sunlight exposure (during safe hours) and a diet rich in calcium and vitamin D are recommended (fortified milk, fatty fish, egg yolks, etc.)
  • If the abnormal bone formation is severe and permanent deformities affecting growth are expected, consider orthopedic corrective surgery (such as fracture correction and osteotomy)
  • Regular blood tests during treatment (calcium, phosphorus, ALP, PTH, 25‑OH vitamin D) and monitoring of kidney function and urine (to check for the risk of excessive calcium excretion and kidney stones)

• Precautions

  • Excessive administration of vitamin D and calcium can cause hypercalcemia and nephrolithiasis, so prescription and monitoring are necessary
  • If the underlying cause (malabsorption, kidney disease, or hereditary disease) is not differentiated and only simple supplementation is provided, treatment failure or recurrence may occur
  • Follow pediatric recommendations for preventive supplementation

Checklist Before an Outpatient Visit (Including Example Questions)

• Items to prepare

  • List of currently used medications and supplements (including vitamins)
  • Previous blood test and X-ray results (photos or reports, if available)
  • Record of when symptoms began and how they have progressed (changes in leg shape, gait, history of fractures, sweating, and seizures)
  • Feeding method (breast milk/formula) and dietary habits (amount of milk and dairy products consumed, frequency of fish and egg consumption)
  • Family history (similar bone problems or hereditary diseases)

• Information to tell the doctor immediately during the visit

  • Whether there have been any recent seizures or episodes of loss of consciousness
  • Suspected acute fracture or severe bone pain
  • Whether active vitamin D or metabolism-related medications are being taken

Examples of General Questions to Ask the Doctor

• "What do my levels (or my child's test results) mean? What additional tests are needed?"
• "What vitamin D and calcium supplementation dose and duration do you recommend?"
• "What side effects should we watch for during treatment? When should we return to the hospital?"
• "What is the long-term prognosis of this disease? What impact will it have on growth and skeletal development?"

Examples of Disease-Specific Questions

• "Based on this child's X-ray findings and blood test results, is it necessary to differentiate nutritional rickets from hereditary rickets (vitamin D–dependent or hypophosphatemic rickets)? What additional tests do you recommend?"
• "If the leg deformity continues in its current state, how likely is orthopedic correction to be necessary? When would be the appropriate time for correction?"

Note: The doses and treatment strategies presented are intended to provide general recommendations and ranges. Actual prescriptions and monitoring vary according to the treating doctor's judgment and the individual patient's circumstances (age, severity, underlying disease, blood test results, etc.).