Osteoporosis and bone remodeling markers
Osteoporosis is a skeletal disorder. It is characterized by a decrease in bone strength, which makes bones more susceptible to fractures.
What is it?
Osteoporosis is a skeletal disorder. It is characterized by a decrease in bone strength, which makes bones more susceptible to fractures.
Bone is a living tissue that grows constantly. It is made up of calcium phosphate and collagen, which give it rigidity and flexibility, respectively. To maintain bone mass, the body needs an adequate supply of calcium and must produce adequate amounts of hormones (e.g., parathyroid hormone, growth hormone, calcitonin, estrogen, and testosterone). Vitamin D is necessary for the absorption of calcium from food, which is absorbed from our diet and also produced in the skin through sunlight.
Throughout life, aged bone tissue is removed (bone resorption performed by osteoclasts) and replaced by new tissue (bone formation performed by osteoblasts) to maintain a healthy bone structure. Until the age of 25/30, bone formation occurs more rapidly than bone resorption; as a result, bones increase in size, weight, and density. From the age of 40/45 onwards, bone resorption becomes faster than bone formation, causing bone tissue to become progressively more fragile.
This change is more rapid in women in the early years of postmenopause and continues throughout life. In men, there is no significant loss of bone mass before the age of 80. Thus, although osteoporosis can affect both men and women, women are usually more affected, especially after menopause.
It is often a “silent disease” for years, with the first symptom usually being a bone fracture. It can occur anywhere in the skeleton, although it is most common in the vertebrae, femur (hip), or forearm (wrist). It also frequently occurs in the ribs and pelvis.
What are the associated symptoms and consequences?
Bone fractures
Prolonged pain
Difficulty standing up
Decreased height and curvature of the back
Deterioration of general health/decreased quality of life
Reduced independence/dependence on others
What are the associated risk factors?
Advanced age
Women
Menopause, especially if it occurs before age 45
History of low-impact fractures after age 40
Family history of hip fractures
Caucasian/Asian ethnicity
Short stature
Thin build
Diet low in calcium and vitamin D
Sedentary lifestyle
Prolonged immobilization
Alcohol, tobacco, and coffee consumption
Medications (cortisone, progesterone, chemotherapy, anticonvulsants)
Diseases (rheumatoid arthritis, malabsorption disorders, chronic kidney disease, hormonal disorders, epilepsy, cancer)
How can I prevent it?
Maintaining bone mass during puberty can be optimized with lifestyle measures such as:
Choosing a healthy diet rich in calcium (milk, yogurt, cheese, green leafy vegetables, cereals, whole wheat bread) and vitamin D (meat, fish, moderate and regular exposure to sunlight)
Regular physical exercise (walking, running)
Avoiding coffee, alcohol, and tobacco
Avoiding falls (avoiding dark/wet sidewalks and carpets; choosing non-slip footwear)
However, these conditions alone do not guarantee that osteoporosis will not develop, as there is a genetic predisposition.
How is it diagnosed?
If your doctor thinks you are at risk of osteoporosis, they may request additional tests: bone densitometry, X-rays, and/or blood tests (calcium, vitamin D, bone remodeling markers).
Bone densitometry is the most important test for diagnosing osteoporosis, as it measures bone mineral density (BMD). The test is recommended for women over 65 and men over 70, or over 50 for both sexes if there are risk factors.
How is it treated?
When osteoporosis is diagnosed, it is usually necessary to use calcium and vitamin D supplements and medications that act on bone metabolism, inhibiting bone loss and/or promoting bone formation.
Fractures must also be treated, sometimes resorting to surgery.
What are bone remodeling markers and why are they important in osteoporosis?
These are substances measured in blood serum or urine that represent bone formation or resorption:
Bone markers are products resulting from the action of osteoblasts in the bone formation process (bone alkaline phosphatase, osteocalcin, type 1 collagen propeptides).
Bone resorption markers are products resulting from the action of osteoclasts in the bone resorption process (hydroxyproline, NTX, CTX).
Bone remodeling markers allow:
Guidance on fracture risk, aiding in the diagnosis of osteoporosis (individuals with elevated resorption markers are at greater risk of fractures, in which case bone markers may be an alternative in the evaluation of patients for whom BMD measurements are not available).
Early assessment of the degree of success/failure in response to the treatment initiated, allowing the physician to optimize the therapeutic approach at an early stage (an inverse correlation is observed between the reduction in bone markers after 3 to 6 months of treatment and bone mass gain, with resorption markers showing the best correlation; the effects on BMD measurement are only noticeable after 1 to 2 years of treatment).
The wide variation in the concentrations of these markers due to their biological and analytical characteristics currently prevents their use in the diagnosis of osteoporosis. However, new research and trials are rapidly being developed in this direction...