An adult human skeleton is made up of 206 bones serving as a framework for the body. These big and small bones provide support, structure, giving the body its shape, allows movement, helps form blood cells along with many essential functions. A bone is nothing but a living, growing tissue that has the tendency to turn over at a rate of about 9 to 11 percent a year. Throughout a person's life span, every single bone tissue is continuously remodeled through collective actions of the bone cells. While normal bone is always undergoing remodeling, it removes old bone tissues and replaces it with fresh and new ones.
Primarily, there are two major types of cells within bone-osteoblasts and osteoclasts. Osteoblasts are the cells that lay down new bone, but first initiate bone resorption by continuously stimulating osteoclasts. Osteoclasts dissolve tiny amounts of bone in the area that require support and strength. This process is done using acid and enzymes to dissolve the humongous network of proteins. Bone markers are certain blood and urine tests to detect bone remodeling, determining if a person has an increased rate of bone turnover, which can suggest bone related diseases and disorders. Monitoring turnover rate of bone tissue being broken down and new bone tissue that is built in its place is what bone marker test is basically done for. They indicate and help determine if the rate of bone resorption or formation is abnormally increased and if there could be a potential bone disorder.
What Are The Potential Bone Markers?
Bone is made up largely of type-I collagen, a protein network that gives the bone its strength and framework, and calcium phosphate, a mineralized complex that hardens its skeletal framework. This combination of collagen and calcium gives the bone its structure. For the measurement of bone-forming activity there are several useful markers and along with it, there are some markers that specifically show bone resorption. Some useful markers may reflect both activities in the body. Markers specific to bone formation include bone-specific alkaline phosphatase, osteocalcin, and N-terminal propeptide of type I procollagen, The markers specific to bone resorption (a process by which the bones are absorbed and broken down by the body) include Bone Sialoprotein, N-terminal telopeptide of type I collagen, C-terminal telopeptide of type I collagen, Hydroxylysine-Glycosides and Cathepsin K.
What Ailments Are Tested With Bone Markers?
An elevated level of bone markers may be seen in many health conditions such as:
- Paget disease
- Metastatic bone disease
- Bone TB
- Rheumatoid arthritis
- Osteogenesis imperfecta
The test is relatively simple just like any other blood profile. By inserting a needle into a vein in the arm, a blood sample is obtained. Sometimes and in certain cases, a timed urine sample is also collected.
Is Any Preparation Needed Before The Bone Turnover Marker Test?
While there are no extreme instructions for the test, there are few things that need to be taken care of. Fasting prior to testing is mandatory. Moreover, bone markers vary in the blood and urine depending upon the time of day or any pattern that recurs every 24 hours (also called diurnal variation), thus timing to collect sample plays a very important role while taking this test.