M08.026.005 Osteomalacia and rickets

Osteomalacia and rickets are metabolic bone diseases caused by a deficiency or impaired metabolism of vitamin D, leading to inadequate bone mineralization. This section explores their characteristics, clinical presentations, and management, equipping medical students with a comprehensive understanding of these conditions.

Causes

Both osteomalacia and rickets stem from insufficient vitamin D, which is crucial for calcium absorption and bone health. Common causes include:

• Dietary deficiency: Inadequate intake of vitamin D-rich foods (fatty fish, eggs, fortified milk)
• Intestinal malabsorption: Conditions like celiac disease or Crohn’s disease can hinder vitamin D absorption.
• Lack of sunlight: Limited sun exposure restricts the body’s natural production of vitamin D.
• Renal and liver disease: These can affect vitamin D metabolism and activation.

Osteomalacia (Adult Disease)

Description: Impaired mineralization of the osteoid matrix in adults, resulting in weak and fracture-prone bones.

Clinical Features:

• Bone pain and tenderness, particularly in the lower back, hips, and wrists.
• Increased risk of stress fractures.
• Muscle weakness and fatigue.

Imaging: X-rays may reveal:

• Looser zones: Transverse lucencies (radiolucent bands) in long bones.

Laboratory Findings:

• Low serum calcium levels.
• Low serum phosphorus levels.
• High alkaline phosphatase levels (may indicate increased bone turnover).

Points to Remember:

• Osteomalacia primarily affects adults with pre-existing risk factors.
• Early diagnosis and treatment are crucial to prevent fractures and disability.

Rickets (Childhood Disease)

Description: Occurs in children where both remodeled bone and newly formed bone at the growth plate are under-mineralized due to vitamin D deficiency.

Clinical Features:

• Skeletal deformities due to impaired enchondral bone formation:
  • Skull: Craniotabes (softening in infants) and frontal bossing (hardening later).
  • Chest: “Rachitic rosary” – a beaded appearance due to costochondral junction enlargement.
  • Spine: Lumbar lordosis (exaggerated inward curvature).
  • Legs: Bowing (genu varum) or knock-knees (genu valgum).
• Delayed growth and development.
• Muscle weakness.
• Increased risk of fractures.

Points to Remember:

• Rickets affect children with growing bones, impacting their development.
• Early intervention promotes proper bone growth and prevents deformities.

Treatment for Both Conditions:

• Vitamin D and calcium supplementation are the mainstay of treatment.
• The specific dosage and duration of therapy depend on the severity of the condition.

Table 1. Summary of Osteomalacia and Rickets

Bibliography:

• National Institutes of Health. (n.d.). Rickets. https://111.wales.nhs.uk/encyclopaedia/y/article/yllechau
• Mayo Foundation for Medical Education and Research. (2022, March 17). Osteomalacia. https://www.mayoclinic.org/medical-professionals/endocrinology/news/oncogenic-osteomalacia-pearls-from-an-elusive-tumor-a-case-from-the-endocrine-teaching-clinics/mcc-20490502pen_spark