Overview
Rickets (nutritional) is a disorder of bone mineralization that occurs in children whose growing bones do not receive enough calcium, phosphorus, or vitamin D. The deficiency impairs the normal ossification of the growth plates, leading to softened, weak bones that can become deformed.
Although once considered a disease of the past in high‑income countries, rickets remains a public‑health concern worldwide. According to the World Health Organization (WHO), an estimated 13 million children are affected globally each year, with the highest prevalence in South Asia, the Middle East, and parts of sub‑Saharan Africa. In the United States, the Centers for Disease Control and Prevention (CDC) report that ≈0.5 % of children under five have biochemical evidence of vitamin D deficiency severe enough to cause rickets, and the rate is higher among exclusively breast‑fed infants with limited sun exposure.
Rickets most commonly appears in children between 6 months and 3 years of age, a critical period of rapid skeletal growth. However, milder forms can continue into late childhood if the underlying nutritional deficits are not corrected.
Symptoms
Because bone growth is ongoing, rickets can manifest with a variety of signs that may be subtle at first. The following list includes the most frequently reported symptoms, each accompanied by a brief description:
- Delayed growth or short stature: Children may fall below growth‑chart percentiles.
- Bone pain or tenderness: Often felt in the legs, ribs, or pelvis, especially after activity.
- Muscle weakness: Difficulty climbing stairs, standing from a sitting position, or walking long distances.
- Widened (bowed) legs: “Bow‑legs” (genu varum) or “knock‑knees” (genu valgum) become noticeable as the child walks.
- Rachitic rosary: A beaded appearance of the ribs that can be felt as nodules along the chest wall.
- Craniotabes: Softening of the skull bones; the skull may feel unusually pliable on palpation.
- Delayed tooth eruption or enamel defects: Teeth may appear later than expected or have porous, discolored enamel.
- Fractures: Even low‑impact falls can lead to bone breaks because the bone matrix is weak.
- Seizures: In severe vitamin D deficiency, low calcium can precipitate seizures, though this is rare.
- General fatigue or irritability: Children may seem unusually tired or fussy.
Causes and Risk Factors
Rickets caused by poor nutrition is most often the result of inadequate vitamin D, calcium, or phosphate intake, or a combination of these deficits. The underlying mechanisms include:
- Vitamin D deficiency: Vitamin D is essential for intestinal absorption of calcium and phosphorus. Deficiency can stem from:
- Insufficient dietary vitamin D (e.g., lack of fortified milk, fatty fish, eggs).
- Limited sunlight exposure – skin synthesis is the primary natural source.
- Dark skin pigmentation, which reduces UV‑B‑mediated vitamin D production.
- Use of sunscreen or clothing that covers most of the body.
- Living at high latitudes (> 35° N or S) where winter sun is weak.
- Calcium deficiency: Diets low in dairy or other calcium‑rich foods (common in lactose‑intolerant or vegan families) reduce the substrate needed for bone mineralization.
- Phosphate deficiency or poor absorption: Rare, but chronic diarrhea, certain medications (e.g., antacids containing aluminum), or renal tubular disorders can lower serum phosphate.
- Malabsorption syndromes: Celiac disease, inflammatory bowel disease, or cystic fibrosis impair absorption of fat‑soluble vitamins, including vitamin D.
Risk groups include:
- Infants who are exclusively breast‑fed beyond 6 months without vitamin D supplementation (the American Academy of Pediatrics recommends 400 IU daily).
- Children with dark skin living in northern latitudes.
- Families with low socioeconomic status who lack access to fortified foods.
- Children with chronic kidney disease, liver disease, or disorders affecting fat absorption.
- Adolescents on strict vegan diets that omit dairy and fortified products.
Diagnosis
Diagnosing nutritional rickets involves a combination of clinical assessment, laboratory testing, and imaging.
Clinical evaluation
The physician looks for classic physical signs (bowed legs, rachitic rosary, craniotabes) and obtains a detailed dietary and sunlight‑exposure history.
Laboratory tests
- Serum 25‑hydroxyvitamin D (25‑OH‑D): The best indicator of vitamin D status. Levels < 20 ng/mL (50 nmol/L) indicate deficiency; < 12 ng/mL (30 nmol/L) is severe.
- Serum calcium and phosphorus: Calcium may be low or low‑normal; phosphorus is typically low in rickets.
- Alkaline phosphatase (ALP): Markedly elevated (often > 2–3× upper limit) because of increased osteoblastic activity.
- Parathyroid hormone (PTH): Elevated secondary hyperparathyroidism is common.
- Renal function tests: To rule out renal causes of phosphate wasting.
Imaging studies
- Plain radiographs (X‑ray) of wrists/knees: Show widened, irregular growth plates (metaphyseal cupping and fraying) and cortical thinning.
- Skull X‑ray: May reveal a “soft” calvarium and the characteristic “rachitic rosary.”
- Bone densitometry (DXA): Occasionally used for monitoring response to therapy.
All results are interpreted in the context of the child’s age and growth stage. The Mayo Clinic and NIH guidelines stress that a combination of low 25‑OH‑D, elevated ALP, and radiographic changes confirms nutritional rickets.
Treatment Options
Therapy aims to replenish deficient nutrients, correct metabolic abnormalities, and allow normal bone growth.
Vitamin D supplementation
- Loading dose: For severe deficiency, 2,000–5,000 IU/kg of vitamin D3 (max 100,000 IU) given orally once, followed by maintenance.
- Maintenance dose: 400–1,000 IU/day for infants; 600–1,000 IU/day for older children, adjusted to keep 25‑OH‑D > 30 ng/mL.
- Vitamin D2 (ergocalciferol) is an alternative, but D3 is more potent.
Calcium supplementation
- Age‑appropriate elemental calcium: 200–500 mg/day for infants, 1,000–1,300 mg/day for school‑age children.
- Calcium carbonate or calcium citrate are common, taken with meals to improve absorption.
Phosphate therapy (rare)
Only indicated when phosphate loss is documented (e.g., renal tubular disorders). Oral phosphate salts are given under specialist supervision.
Dietary modifications
- Increase intake of fortified dairy (milk, yogurt, cheese) or fortified plant milks.
- Include fatty fish (salmon, mackerel), egg yolks, and fortified cereals.
- For vegan families, add calcium‑fortified soy/almond milks and consider a vitamin D‑fortified nutritional supplement.
Sunlight exposure
Safe, regular exposure (10–15 minutes of midday sun to arms and legs, 2–3 times per week) can boost endogenous vitamin D, but should be balanced against skin‑cancer risk.
Monitoring
Follow‑up labs are typically repeated at 4–6 weeks to ensure 25‑OH‑D and calcium have normalized, then every 3–6 months until radiographic healing is evident.
When surgical intervention is needed
Severe deformities that impair gait or cause pain may require orthopedic correction (e.g., guided growth plates, osteotomies). This is usually considered only after biochemical correction.
Living with Rickets (nutritional)
Even after treatment begins, families need practical strategies to support recovery and prevent recurrence.
- Adhere to supplement schedule: Use a pill‑organizer or set alarms to avoid missed doses.
- Incorporate fortified foods: Serve fortified milk or orange juice at breakfast; add cheese to snacks.
- Encourage safe outdoor play: Daily activity in sunlight helps maintain vitamin D levels.
- Monitor growth: Track height and weight on a growth chart; report plateauing to your pediatrician.
- Physical therapy: Gentle stretching and strengthening exercises improve muscle tone and gait.
- Educate caregivers and teachers: Ensure school personnel understand the child’s needs (e.g., allowance for short breaks to avoid fatigue).
- Regular medical review: Keep scheduled appointments for labs and X‑rays, even after symptoms improve.
Prevention
Because nutritional rickets is largely preventable, public‑health and individual measures are critical.
- Vitamin D supplementation for infants: The American Academy of Pediatrics recommends 400 IU/day for all breast‑fed infants from birth to 12 months, and continuing through childhood if risk factors persist.
- Fortified foods: Choose milk, yogurt, orange juice, and cereals fortified with ≥ 400 IU vitamin D per serving.
- Dietary counseling: Parents with dietary restrictions (vegan, lactose intolerance) should consult a dietitian to ensure adequate calcium and vitamin D intake.
- Sun exposure guidelines: 10–15 minutes of midday sun, 2–3 times per week, is generally sufficient for most latitudes; higher latitudes require longer exposure or supplementation.
- Screening high‑risk groups: Routine 25‑OH‑D testing for infants with dark skin, limited sun, or exclusive breastfeeding without supplements.
- Public health policies: Community fortification programs (e.g., adding vitamin D to staple foods) have successfully reduced rickets incidence in many countries (see WHO reports).
Complications
If left untreated, nutritional rickets can lead to serious and sometimes irreversible problems:
- Severe bone deformities: Permanent bowing or shortening of long bones, requiring orthopedic surgery.
- Growth retardation: Failure to achieve normal adult height.
- Hypocalcemic seizures: Low serum calcium can precipitate seizures, especially in infants.
- Dental abnormalities: Delayed eruption, enamel hypoplasia, and increased susceptibility to cavities.
- Fractures: Even low‑impact trauma may cause breaks, increasing morbidity.
- Cardiovascular problems: Chronic hypocalcemia can affect cardiac conduction, though rare.
When to Seek Emergency Care
- Sudden, severe muscle cramps or tetany (spasms) in the hands, feet, or face.
- Seizures or convulsions, especially if they are accompanied by a loss of consciousness.
- Difficulty breathing or rapid, shallow breathing (signs of severe hypocalcemia).
- Unexplained loss of consciousness or fainting.
- Any sign of a broken bone after a minor fall.
These are medical emergencies that require immediate evaluation and treatment.
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**References**
- American Academy of Pediatrics. Vitamin D Supplementation Recommendations. Pediatrics. 2023.
- Centers for Disease Control and Prevention. Vitamin D Deficiency and Rickets. CDC Health Topics. Updated 2022.
- Mayo Clinic. Rickets. https://www.mayoclinic.org/diseases-conditions/rickets/diagnosis-treatment
- National Institutes of Health Office of Dietary Supplements. Vitamin D Fact Sheet for Health Professionals. 2024.
- World Health Organization. Guidelines on Micronutrient Fortification. 2021.
- Cleveland Clinic. Rickets in Children: Symptoms, Diagnosis, and Treatment. 2022.