Adult Onset Rickets: How It’s Diagnosed

Adult onset rickets—more accurately called osteomalacia—is a condition where bones become soft and weak due to defective mineralization. Though often associated with children, vitamin D deficiency and other causes can lead to rickets-like changes in adults. Recognizing and diagnosing adult onset rickets early helps prevent fractures, muscle weakness, and long-term bone deformities.

What Causes Adult Onset Rickets?

Several factors interfere with normal bone mineralization in adults:

• Vitamin D deficiency
– Inadequate sun exposure (e.g., indoor lifestyle, high-latitude living)
– Poor dietary intake of vitamin D–rich foods
– Malabsorption (celiac disease, Crohn’s, bariatric surgery)

• Impaired vitamin D activation
– Chronic kidney disease (decreased conversion to active form)
– Liver disease (impaired 25-hydroxylation)

• Mineral deficiencies
– Low dietary calcium or phosphate intake
– Excessive phosphate loss (renal phosphate-wasting disorders)

• Medications and toxins
– Anticonvulsants (phenobarbital, phenytoin)
– Bisphosphonates (rarely, when misused)
– Aluminum-containing antacids

• Genetic or rare metabolic conditions
– Hypophosphatasia
– X-linked hypophosphatemia

Signs and Symptoms

Adult onset rickets may develop gradually. Early warning signs can be subtle:

• Bone pain or tenderness, especially in the hips, pelvis, lower back and legs
• Muscle weakness, often in thighs and shoulders
• Difficulty walking, climbing stairs or rising from a chair
• Frequent fractures with minimal trauma
• Bone deformities (in severe, long-standing cases)

Because symptoms overlap with osteoporosis, fibromyalgia or arthritis, a thorough evaluation is essential.

Step-By-Step Diagnostic Approach

1. Detailed Medical History
   • Sun exposure habits, dietary patterns, supplement use
   • Gastrointestinal symptoms suggesting malabsorption
   • Family history of metabolic bone disease
   • Medication review (anticonvulsants, antacids, others)

2. Physical Examination
   • Assessment of posture and gait
   • Palpation of bony prominences for tenderness
   • Evaluation of muscle strength (e.g., rising from seated position)
   • Check for pelvic tilt or chest wall deformities

3. Laboratory Tests
   A panel of blood and urine tests helps pinpoint the cause:
   • Serum 25-hydroxyvitamin D (best indicator of vitamin D status)
   • Serum calcium and phosphate levels
   • Parathyroid hormone (PTH)
   • Alkaline phosphatase (often elevated with defective mineralization)
   • Creatinine and estimated glomerular filtration rate (kidney function)
   • 24-hour urinary calcium and phosphate (to assess losses)

   Typical findings in adult onset rickets (osteomalacia) include:
   – Low or low-normal calcium and phosphate
   – High PTH (secondary hyperparathyroidism)
   – Elevated alkaline phosphatase
   – Low 25-hydroxyvitamin D

4. Imaging Studies
   • X-rays
   – Diffuse osteopenia (bone thinning)
   – Pseudofractures (Looser’s zones) in ribs, pelvis, femur edges
   • Bone densitometry (DXA scan)
   – Confirms low bone density but cannot distinguish osteomalacia from osteoporosis
   • MRI or bone scan (in select cases)
   – Detects stress fractures or areas of active bone remodeling

5. Specialized Tests (as needed)
   • Bone biopsy with histomorphometry (rarely needed)
   – Shows unmineralized osteoid (characteristic of osteomalacia)
   • Genetic testing (if inherited phosphate-wasting disorder suspected)

Differential Diagnosis

Because many bone disorders can mimic adult onset rickets, your doctor may consider:
• Osteoporosis
• Paget’s disease of bone
• Rheumatoid arthritis or other inflammatory arthritis
• Fibromyalgia
• Primary hyperparathyroidism

Accurate diagnosis relies on combining clinical, laboratory and imaging data.

Treatment Overview

Once adult onset rickets is confirmed, treatment targets the underlying cause and supports bone healing:

• Correct vitamin D deficiency
– High-dose vitamin D2 or D3 supplements
– Maintenance dosing to keep 25-hydroxyvitamin D in optimal range

• Restore mineral balance
– Dietary calcium (1,000–1,200 mg/day)
– Phosphate supplements (if low)

• Address malabsorption or kidney issues
– Manage celiac disease, Crohn’s or other GI disorders
– Adjust medications that interfere with vitamin D metabolism

• Monitor response
– Repeat labs (calcium, phosphate, PTH, alkaline phosphatase) every 3–6 months
– Follow-up imaging as needed to confirm pseudofracture healing

When to Seek Professional Help

If you experience persistent bone pain, muscle weakness or new fractures, it’s important to take action:

• Talk to your primary care physician or an endocrinologist.
• Consider a free, online symptom check, using the doctor approved Ubie Symptom Checker.
• Share your medical history, lab results and any imaging with your healthcare team.

These steps can help you get the right tests quickly and reduce the risk of complications.

Preventing Anxiety While Staying Informed

Learning about adult onset rickets might feel overwhelming, but early diagnosis and treatment often lead to full recovery of bone strength. Keep in mind:

• Many people improve with simple vitamin D and calcium supplementation.
• Regular follow-up ensures treatment is working.
• Lifestyle changes (diet, safe sun exposure, weight-bearing exercise) reinforce bone health.

If you have concerns or notice troubling symptoms—especially sudden bone pain or difficulty with daily activities—reach out to your doctor without delay.

Final Thoughts

Adult onset rickets is treatable when identified promptly. By combining a careful history, focused lab tests and appropriate imaging, healthcare providers can distinguish osteomalacia from other bone disorders. Early intervention restores bone integrity, reduces pain and lowers fracture risk.

Remember, nothing replaces the expertise of a qualified physician. If you suspect a serious or life-threatening issue, always speak to a doctor right away. Regular check-ups, good nutrition, and awareness of your body’s signals are key to maintaining strong, healthy bones.