Understanding the difference between rickets and osteomalacia
Most people associate rickets with children, and for a good reason. Rickets impacts the soft, developing bone tissue at the growth plates, leading to skeletal deformities like bowed legs during rapid growth phases. In contrast, adults have fully mature, fused growth plates. When adults experience a similar bone softening condition, it is medically known as osteomalacia.
Although the names differ based on the patient's age and skeletal maturity, the underlying cause is often the same: a severe and prolonged deficiency of vitamin D. Without adequate vitamin D, the body cannot absorb calcium and phosphorus properly, leading to defective mineralization of bone tissue. This defect can cause significant bone pain, muscle weakness, and an increased risk of fractures in older adults.
Why older people are at higher risk for osteomalacia
Several age-related factors contribute to a higher risk of vitamin D deficiency and, subsequently, osteomalacia in older adults:
- Reduced sun exposure: Many older people, particularly those who are homebound, institutionalized, or live in northern latitudes, get very little direct sunlight. Since the skin produces vitamin D in response to sun exposure, this is a major contributing factor.
- Decreased skin efficiency: With age, the skin's ability to synthesize vitamin D from sunlight decreases significantly. One study showed a 70-year-old produces less than half the vitamin D that a 20-year-old does from the same sun exposure.
- Dietary insufficiency: Older adults may have a reduced appetite or dietary habits that lack sufficient vitamin D and calcium. Malabsorptive conditions, or reduced gut absorption, can also play a role.
- Compromised organ function: The kidneys and liver are crucial for converting vitamin D into its active form. Age-related changes or pre-existing conditions affecting these organs can impair this process.
- Certain medications: Some medications, including particular anti-seizure drugs, can interfere with vitamin D metabolism.
Symptoms and diagnosis of osteomalacia in older adults
The symptoms of osteomalacia can be subtle and easily confused with other age-related issues, leading to delayed diagnosis. Common signs include:
- Generalized, dull, aching bone pain, most often in the lower back, hips, pelvis, and legs.
- Muscle weakness and stiffness, particularly in the thighs and upper arms.
- A characteristic waddling gait due to muscle weakness and pain.
- Increased risk of fractures from minimal trauma.
- Fatigue and a general sense of being unwell.
To diagnose osteomalacia, a healthcare provider will typically order a series of tests, including blood tests to measure levels of vitamin D, calcium, and phosphorus, and a bone density scan (DEXA) or X-rays to look for signs of bone softening or fractures. A bone biopsy, while invasive, is the gold standard for confirmation.
Osteomalacia vs. osteoporosis: a comparison
It's important to differentiate osteomalacia from osteoporosis, another common bone condition in older adults. While both increase fracture risk, their underlying pathology and treatment differ significantly.
Feature | Osteomalacia (Adult Rickets) | Osteoporosis |
---|---|---|
Underlying Cause | Inadequate mineralization of newly formed bone tissue due to severe vitamin D, calcium, or phosphate deficiency. | Loss of existing bone mass and density, making bones porous and brittle. |
Bone Composition | Bone matrix (collagen) is present, but it is soft and unmineralized. | The amount of bone tissue is decreased, but its mineralization is normal. |
Primary Symptom | Persistent, generalized bone and muscle pain, often a hallmark symptom. | Often called a "silent disease" with no symptoms until a fracture occurs. |
Treatment Focus | Primarily involves supplementation with vitamin D and calcium to restore mineralization. | Focuses on slowing bone loss with medications and managing underlying causes. |
Radiological Findings | May show characteristic pseudofractures or Looser zones. | Shows decreased bone mineral density on DEXA scans. |
Treatment and prevention
Fortunately, osteomalacia caused by nutritional deficiencies is often curable with straightforward treatment. The main goals are to replenish the deficient nutrients and address any underlying conditions.
- Supplementation: The primary treatment is high-dose vitamin D and calcium supplementation, prescribed and monitored by a doctor. Dosage and duration depend on the severity of the deficiency and the patient's underlying health.
- Dietary changes: A dietitian can help create a meal plan rich in vitamin D and calcium. This includes foods like oily fish (salmon, sardines), fortified milk and cereals, and green leafy vegetables.
- Controlled sun exposure: Regular, safe exposure to sunlight can help the body naturally produce vitamin D. A healthcare provider can offer guidance on safe exposure times.
- Addressing underlying issues: For cases caused by malabsorption, liver, or kidney disease, treating the primary condition is necessary.
Prevention in older adults focuses on regular vitamin D intake, especially through supplementation, as skin synthesis decreases with age. Ensuring adequate calcium intake and getting moderate exercise are also vital for maintaining bone health and reducing fall risk. For those with mobility issues, daily low-dose vitamin D supplements are a practical and effective way to avoid deficiency.
Conclusion
While the term "rickets" is specific to children, older people can absolutely suffer from its adult counterpart, osteomalacia. Driven largely by vitamin D deficiency, this condition causes bone softening that leads to significant pain, muscle weakness, and a heightened risk of fractures. Early detection and proper treatment with supplementation, coupled with dietary and lifestyle adjustments, can effectively reverse the condition and dramatically improve an older person's quality of life. Awareness of the risk factors and symptoms is key, as is proactive communication with healthcare providers about bone health concerns.
Visit the NHS website for more information on the differences between rickets and osteomalacia.