Bone Metabolism Disorder

Bone metabolism disorders are a group of conditions that weaken your bones by disrupting the balance of minerals like calcium, phosphorus, and vitamin D. While some people are born with these disorders, others develop them later in life due to lifestyle factors, medical conditions, or medications.

Table of contents

• What Are Bone Metabolism Disorders?
• Types of Bone Metabolism Disorders
• How Common Are These Disorders?
• What Causes Bone Metabolism Disorders?
• Risk Factors
• Symptoms
• How Are These Disorders Diagnosed?

What Are Bone Metabolism Disorders?

Bone metabolism disorders are conditions that affect your bone strength and health. Throughout your life, your bones constantly grow and change. New bone cells replace old ones about every 10 years or so. This ongoing process is called bone turnover, which is when new bone tissue replaces older bone tissue.^[1]

These disorders happen when mineral imbalances interfere with your bone mass, growth, and turnover. Mineral imbalances mean having too much or too little of important minerals like calcium, phosphorus, or vitamin D. Your bones store these minerals and use them to rebuild and grow.^[1]

The disorders result from an abnormal bone chemical environment that leads to a defective skeleton and bone abnormalities. Factors that affect your bone cell activity, such as genetic conditions and vitamin deficiencies, usually cause the mineral imbalances that lead to weakened bones.^[2]

Bone metabolism disorder can be congenital (meaning you’re born with it) or acquired (meaning you developed it later in life).^[1]

Types of Bone Metabolism Disorders

Several different types of bone metabolism disorders exist, each affecting bones in different ways. The most common and some of the rarer conditions include:^[1][6]

• Osteoporosis – The most common type, resulting in loss of bone mass and leading to bone weakness and higher risk of fractures
• Osteopenia – A less severe form of low bone density
• Osteomalacia (called rickets in children) – A condition where bones don’t mineralize properly
• Osteogenesis imperfecta – Also known as “brittle bone disease,” a genetic condition affecting bone formation
• Paget’s disease – A disorder that disrupts the normal bone remodeling process
• Hypophosphatasia – A rare genetic disorder affecting bone mineralization
• Cushing syndrome – A hormonal disorder that can weaken bones

How Common Are These Disorders?

Some bone metabolism disorders are much more common than others. Osteoporosis is by far the most common, affecting about 200 million people worldwide. In the United States, approximately 12.6% of Americans aged 50 or over have osteoporosis.^[1]

In contrast, osteogenesis imperfecta is much less common. About 25,000 to 50,000 people in the United States have this condition. Other bone metabolism disorders like osteomalacia, hypophosphatasia, and Paget’s disease are also less common than osteoporosis.^[1]

What Causes Bone Metabolism Disorders?

Not having enough minerals in your bones can gradually weaken or damage them, leading to bone metabolism disorders. These mineral imbalances, whether you’re born with them or develop them later in life, can affect mineral homeostasis – your body’s way of making sure it has the right amounts of calcium, vitamin D, and phosphorus.^[1]

Bone is composed of proteins and minerals. The protein mainly consists of type I collagen, and the minerals are made up primarily of calcium and phosphate. About 5-10% of the bone skeleton is replaced every year in adulthood. Importantly, about 85% of the body’s phosphate and 99% of its calcium are contained within the skeleton as hydroxyapatite, a mineral compound that gives bones their strength.^[2]

Primary failure of organs that are crucial in calcium balance can lead to metabolic bone disorders. Abnormalities of minerals including calcium, phosphorus, magnesium, or vitamin D can develop as a result of dysfunctions in various factors that control mineral homeostasis. The defective mineralization can translate into rickets at the level of the growth plates and osteomalacia on the bone surfaces.^[2]

Risk Factors

A risk factor is something that increases your chances of developing a condition. Many factors can put you at higher risk for bone metabolism disorders:^[1]

Age and lifestyle factors:

• Being 65 years of age or over
• Smoking
• Early menopause (before age 45)
• Inadequate sun exposure (lack of vitamin D)
• Being petite or having a smaller frame
• Not getting enough exercise

Medical treatments:

• Prior hormone therapy for breast or prostate cancer
• Being an organ transplant recipient
• Long-term use of antiseizure medications

Family history:

• Strong family history of osteoporosis (especially if a biological parent fractured their hip)

You’re also more likely to develop bone metabolism disorders if you have certain health conditions, including:^[1]

• Hyperparathyroidism – Overactivity of the parathyroid glands
• Hypophosphatemia – Low phosphorus in your blood
• Vitamin D deficiency
• Calcium deficiency
• Kidney disease
• Alcohol use disorder
• Malabsorption – Difficulty absorbing nutrients from food
• Malnutrition

Symptoms

Symptoms of bone metabolism disorders vary from person to person. Some people may experience several symptoms, while others may have none at all. It’s important to note that osteoporosis is a silent disease, meaning it causes no pain until a fracture occurs.^[1]

Common symptoms may include:^[1]

• A decline in height (getting shorter by at least an inch)
• Broken bones that occur with minimal trauma
• Change of posture (stooping or bending forward)
• Difficulty walking
• Lower back pain
• Muscle weakness
• Pain in your bones or hips
• Difficulty breathing (smaller lung capacity caused by compressed, or pinched, disks in your spine)

How Are These Disorders Diagnosed?

Your healthcare provider may use one or more methods to diagnose bone metabolism disorders. The main diagnostic tool is blood testing, which can measure levels of calcium, phosphorus, vitamin D, and other substances that affect bone health.^[1]

Healthcare professionals often diagnose osteoporosis during routine screening for the disease. It’s also commonly found when a broken bone is X-rayed or during an X-ray taken for another reason, such as a chest X-ray. Your health professional may perform a physical exam to check for changes in your height and posture, among other things.^[8]

Your health professional may order a test to check your bone density. Your bone density can be measured with a machine that uses low levels of X-rays to determine the proportion of mineral in your bones. During this painless test, you lie on a padded table as a scanner passes over your body. In most cases, only certain bones are checked, usually those in the hips and spine.^[8]

Metabolic bone disease, MBD, bone disease