Contents
PINP (Type I N-terminal propeptide of procollagen) is a protein that is a marker of the process of bone formation (bone formation). The peptide is released during the extracellular synthesis of collagen – a structural component of bone tissue. One of the indications for testing this protein is skeletal disorders (fractures, deformities, osteoporosis).
A few words on the N-terminal propeptide of procollagen type I
The N-terminal propeptide of type I procollagen is a protein released during collagen synthesis from type I procollagen and metabolized in the liver. The concentration of this marker in the blood shows both the process and dynamics of collagen production and bone formation. PINP particles are small, so they easily get from the glomeruli into the urine, where this protein can also be determined. The half-life of PINP in serum is a few minutes. Its highest concentration is observed at night, while in the afternoon its level drops. The N-terminal propeptide can also come from muscle, skin, and other tissues.
When do we perform the PINP test?
The most common indications for the PINP test are listed below.
1. Skeletal disorders (osteoporosis, pathological fractures, skeletal deformities, calcium-phosphate disturbances).
2. Metabolic diseases of bone tissue (Paget’s disease, adynamic bone disease).
3. Increased bone turnover (hyperparathyroidism, hypercalcemia, hyperthyroidism).
The course of the study
Material needed for the PINP test: serum or plasma.
Preparation for the test: on an empty stomach (at least 8 hours).
The course of the examination: one-time blood sampling from a vein in the arm.
Time of waiting for the result: 1 day.
Norm: 20-90 ng/l.
Comments: The peptide is released into the extracellular space from the amino terminus of the procollagen. It is also formed in tissues other than bone that produce type I collagen. The PINP concentration reflects the number of newly formed collagen molecules. The increase in the level of bone formation markers may be the result of an increase in the number of bone remodeling sites, extension of the bone formation phase in remodeling units or the activation of bone formation processes in various places of remodeling (on the surface of the bone trabeculae, the surface of the cortical bone from the medullary canal, subperiosteal surface cortical bone).