202 1 Tianjin medical laboratory science: bone metabolism index
The human skeleton is undergoing metabolism all the time. Every day, a certain amount of bone tissue is absorbed and a considerable amount of bone tissue is synthesized, and old bones are constantly replaced by new bones. This process is called bone transformation (also called bone metabolism). Under normal circumstances, bone resorption dominated by osteoclasts and bone formation dominated by osteoblasts are in a dynamic balance, so the bone mass can remain relatively stable. When bone resorption and bone formation are unbalanced, it can lead to various metabolic bone diseases.
Bone metabolic markers are metabolites in the process of bone tissue absorption and synthesis, also known as bone turnover. Biochemical markers of bone metabolism are metabolites in the process of bone tissue absorption and synthesis, also known as biochemical markers of bone transformation or bone metabolism markers, which can be divided into bone formation markers and bone absorption markers. The former represents the metabolites of osteoblast activity and bone formation, while the latter represents the metabolites of osteoclast activity and bone absorption.
What are the commonly used indicators of bone metabolism? Commonly used indicators of bone metabolism are: 25- hydroxyvitamin D, parathyroid hormone (PTH), calcitonin (CT), 1 procollagen amino-terminal propeptide (P 1NP).
There are two sources of 1.25- hydroxyvitamin D: one is synthesized by skin after sunlight, and the other is food supplement (milk, eggs, cod liver oil, etc. ). Vitamin D can promote calcium absorption and bone calcification. The determination of 25- hydroxyvitamin D can show whether the human body lacks vitamin D.
2. Parathyroid hormone (PTH) is a calcium regulating hormone secreted by parathyroid main cells. Its main function is to enhance the number and activity of osteoclasts, promote calcium absorption in renal tubules and intestines, and increase blood calcium.
3. Calcitonin (CT) is a peptide hormone synthesized and secreted by thyroid follicular cells. Its function is just the opposite of PTH. Its main function is to inhibit the activity of osteoclasts and reduce bone resorption. In addition, it can inhibit the absorption of calcium and phosphorus in renal tubules and intestines.
4. Osteocalcin is synthesized and secreted by osteoblasts and participates in the process of bone mineralization. The level of osteocalcin can reflect the activity of osteoblasts and bone formation. The faster bone renewal, the higher BGP level, and vice versa. This index is often used to judge the bone turnover rate and guide the clinical medication of osteoporosis.
5. 1 procollagen N-terminal propeptide (P 1NP) is the product of osteoblasts' synthesis of 1NP collagen, which is an indicator of bone formation. The increase of P 1NP indicates that the osteogenic activity is enhanced.
The clinical application of bone metabolic markers is mainly used to distinguish the types of osteoporosis, predict the risk of bone loss and fracture, evaluate the prognosis of osteoporosis, guide the selection of anti-osteoporosis drugs and evaluate the efficacy of anti-osteoporosis drugs. It should be pointed out that the level of bone metabolic markers can only reflect the speed of bone loss, and can not be used as a diagnostic basis for osteoporosis. To diagnose osteoporosis, we still need to rely on the history of brittle fracture and the bone density measured by dual-energy X-ray absorptiometry (DXA).