Metabolic bone diseases include osteoporosis, osteomalacia (rickets) and hyperparathyroidism. These conditions can cause weakened bone, loss of bone, frequent fractures or delayed growth in children.

Metabolic Bone Disorders: What You Need to Know

• Metabolic bone disorders result from abnormally low levels of calcium and phosphorus, minerals that support the growth and strength of the bones.
• Symptoms include aching bones and frequent fractures in older adults, or delayed bone growth in children.
• Bone disorders are managed by addressing the cause of the calcium deficiency, which can involve treatments such as surgery, radiation or nutritional supplements.

What is metabolic bone disease?

Metabolic bone disease is a weakening of the bones caused by abnormal levels of the bone’s “building blocks,” such as calcium, phosphorus or of vitamin D. Diseases or conditions that cause deficiencies in any of these things can lead to bone loss, fragile bones, fractures, bone deformities and serious disability.

Types of Metabolic Bone Disorders

Metabolic bone conditions can affect adults and children.

Osteoporosis

Osteoporosis is a metabolic bone disease. Some bone loss may occur in older adults over time due to hormonal changes and aging, but factors such as decreased estrogen in women, a family history of the condition, small bones, poor diet, excessive alcohol use and smoking can weaken bones and worsen osteoporosis.

Osteomalacia

Osteomalacia, sometimes called rickets, causes weak or softened bones in children from a lack of sufficient calcium or phosphorus. Vitamin D allows the body to absorb these minerals to help bones grow and maintain bone strength. A vitamin D deficiency can result from poor diet, lack of sunlight or an inability to absorb the vitamin because of an intestinal condition such as celiac disease, medications or an inherited disorder.

Learn more about vitamin D and calcium.

Parathyroid Problems and Bone Disease

Conditions of the parathyroid glands can lead to bone disorders. The parathyroid glands are small glands located in the neck. They produce parathyroid hormone, or PTH.

The job of PTH is to regulate calcium and phosphorus in the blood, which are both essential to bone health. When a problem affects the function of the parathyroid glands, lack of these minerals can cause the bones to become weak, fragile or deformed.

The parathyroid diseases that can affect the mass and structure of your bones include:

• Parathyroid tumor
• Primary or secondary hyperparathyroidism, which can be caused by:
  • Previous head and neck radiation treatments
  • Use of lithium medications

Causes of Metabolic Bone Disease

Metabolic bone disorders can affect anyone, but are more likely to occur in people who:

• Have a vitamin D deficiency
• Are older (except osteomalacia, which affects children)
• Have a small body size
• Have kidney disease
• Do not get much sunlight, which provides vitamin D
• Have had organ transplants
• Have been treated with hormones for prostate cancer or breast cancer
• Experience menopause before age 45
• Have a medical condition that prevents absorption of vitamin D
• Smoke
• Take steroids
• Drink alcohol excessively

Metabolic Bone Disease Symptoms

People with metabolic bone disease may experience:

• Aching bones, especially in the back, hips and legs
• Delayed growth (in children)
• Curving of the spine
• Tooth problems
• Loss of height due to compression of vertebrae (bones of the spine)
• Knees that bow outward or “knock” knees that bend inward
• Frequent fractures, especially:
  • Those occurring in people over 55
  • Those caused by falls from a standing height or less, which can indicate abnormally fragile bones
• Fragility fractures (breaking a bone when falling from standing height of less) that occur after menopause or in older men should not be thought of as a normal part of aging. When this happens, a doctor should evaluate the person for metabolic bone disorders, including bone density testing.

Metabolic Bone Disease Diagnosis

Identifying the cause of weakened bones helps the doctor recommend the best possible treatment. Some of the tests that help diagnose metabolic bone disease include:

• DEXA (dual energy X-ray absorptiometry) scan, a type of X-ray that measures mineral content in the bones
• Bone density test
• Blood test to assess levels of calcium, phosphorus and vitamin D in the blood
• Scans of the parathyroid glands, such as CT, ultrasound or MRI

Metabolic Bone Disease Treatment

Managing metabolic bone, calcium and parathyroid disorders can be complex and requires the patient and endocrinologist working together to determine the underlying cause and implementing an appropriate treatment plan.

Medications for Metabolic Bone Disease

Depending on the root cause of the bone loss, the doctor may treat the problem by prescribing:

• Parathyroid hormone
• Estrogen
• Biophosphonate medications
• Calcitonin
• Denosumab injections
• Vitamin D and calcium supplements

Other Treatments

If the bone disease is due to a parathyroid tumor, the doctor may recommend treatment such as surgery (parathyroidectomy) or radiation, depending on whether the tumor is benign (noncancerous) or malignant (cancerous).