Ntx-Telopeptide

What is the composition of human bone?

It is composed of organic(30%) and mineral matter(70%). The chief component of mineral matter is Hydroxyapatite and organic matter is Type 1 collagen apart from few other cells such as osteoclasts, osteoblast & osteocytes.

What is collagen?

It is the most abundant structural protein present in the body’s various connective tissue making up to 30-35% of whole-body protein content. It is a triple-helical fibrillar structure (collagen helix ) comprising amino acids. It is found most commonly in connective tissue such as cartilage, bones, tendons, ligaments and skin with various degrees of mineralization giving it rigidity. Collagen has 5 main types :

Type 1 : Skin ,Tendon ,Bone
Type 2: Cartilage
Type 3: Reticular fibers.
Type 4: Basement membrane.
Type 5: Hair, Placenta.

What is N terminal Telopeptide?

It is an Amino-terminal telopeptide of fibrillar collagen Type    1 and Type 2. It is used as a biomarker to measure bone turnover. It can be measured in urine or blood.

What are Bone Biomarkers?

These are the measurable indicators in blood and urine tests that detect products of bone remodeling to help determine if the rate of bone resorption or formation is abnormally increased.

Which are bone formation markers?

These are serum total and bone-specific alkaline phosphatase, osteocalcin, C terminal propeptide of protocollagen type 1 (P1CP),N terminal propeptide of protocollagen type 1 (P1NP).

Which are bone markers for resorption

Serum biomarkers such as TRAP i.e. Tartarate resistant acid phosphatase, C terminal telopeptide, N terminal telopeptide. Urine markers include Urine calcium, Hydroxyproline,N terminal telopeptide, C terminal telopeptide, Pirydinoline.

Why do we need to get tested for bone biomarkers?

Bone is a rigid connective tissue forming skeleton of humans. It is a living tissue which approximately 10% gets replaced every year through a process known as bone remodeling comprising of bone resorption and bone formation. The combination of bone collagen and calcium gives it rigidity. More than 99 % of the body's calcium is stored in bones and enamels. There are two main types of cells within the bone, Osteoblast( for new bone formation ) and Osteoclast ( for bone resorption). Osteoclasts dissolve the small bone portion that needs to be replaced and strengthened using acid enzymes to dissolve bone. Osteoblast then initiates new protein formation which eventually gets mineralized with calcium and phosphates. In the early years of life new bone formation happens at a faster rate than resorption until age 30 years. After this peak resorption occurs faster than bone formation called age-related osteoporosis. There are many diseases that cause an imbalance between the formation and resorption of bones resulting in pathological osteoporosis. Bone loss may occur in conditions such as rheumatoid arthritis, hyperparathyroidism, Cushing disease, chronic kidney disease, multiple myeloma. During childhood, bone markers help in diagnosing metabolic bone diseases and in monitoring their treatment eg rickets, juvenile paget's disease, osteogenesis imperfecta.

What are the signs and symptoms of the bone disorder?

Pain in bones and joints, Fractures occurring without serious injury, delayed or deformed bone growth in children, brittle teeth.

What other tests should be done?

C terminal telopeptide, P1NP ( Procollagen type 1 N terminal propeptide ), Deoxypyridinoline (DPD), Pyridinium crosslink, Tartarate resistant acid phosphatase (TRAP), Bone specific alkaline phosphatase, Osteocalcin.

What is DEXA scan?

It is Dual energy X-ray absorptiometry, used for measuring bone mineral density. It is typically used to diagnose and follow up for bone-related health problems such as osteoporosis. This test can also measure body fat and muscle mass.

What is Metabolic bone disorder?

Any systemic condition that results in reduced bone strength, altered mineralization or composition. Abnormal formation of organic matrix leads to osteogenesis imperfect also known as a brittle bone disease caused by deficiency of type 1 collagen and is the most common congenital connective tissue disorder. Abnormal mineralization may result in osteomalacia, rickets caused by deficiency of Vitamin D or calcium in the diet. Abnormal resorption due to Hyperparathyroidism,Paget's disease, osteoporosis, osteopetrosis.