Beyond the Traditional DEXA Scan...

Thank you to all that attended our “Bone Health Secrets” Workshop, in collaboration with OsteoStrong Brea.

As promised, here are some helpful markers to evaluate bone health beyond the DEXA Scan….

Bone Health Markers

The International Osteoporosis Foundation (IOF) and the International Federation for Clinical Chemistry (IFCC) recommend two blood tests for evaluating bone turnover:

· C-telopeptide (C-terminal telopeptide of type 1 collagen (CTx)) – a marker for bone resorption. It is a peptide fragment from the carboxy terminal end of the protein matrix; used to monitor anti-resorptive therapies, such as bisphosphonates and hormone replacement therapy, in postmenopausal women and people with low bone mass (osteopenia)

· P1NP (Procollagen type 1 N-terminal propeptide) – a marker for bone formation. It is formed by osteoblasts; reflects rate of collagen and bone formation; may be ordered along with bone resorption marker such as C or N-telopeptide; most sensitive marker of bone formation and particularly useful for monitoring bone formation therapies and anti-resorptive therapies; it is recommended that the test be performed at baseline before starting osteoporosis therapy and again 3 to 6 months later.

Other urine or blood tests used less commonly for bone resorption include:

· N-telopeptide (N-terminal telopeptide of type 1 collagen (NTx)) – a peptide fragment from the amino terminal end of the protein matrix; another marker used to monitor therapy.

· Deoxypyridinoline (DPD) – a collagen breakdown product with a ring structure.

· Pyridinium Crosslinks – a group of collagen breakdown products that includes DPD; used to monitor therapy response; not as specific for bone collagen as the telopeptides.

· Tartrate-resistant acid phosphatase (TRAP) is the version of acid phosphatase produced by osteoclasts, the cells that dissolve small amounts of bone, during bone resorption.

Other bone formation blood tests that may sometimes be used include:

· Bone-specific alkaline phosphatase (ALP) – one of the isoenzymes (types) of ALP; it is associated with osteoblast cell function, the type of cell involved in bone formation. It is thought to have a role in bone mineralization; it is recommended that the test be performed at baseline before starting osteoporosis therapy and again 3 to 6 months later; results may be affected by the level of liver ALP.

· Osteocalcin (bone gla protein) – a protein formed by osteoblasts; part of the non-collagen portion of the bone structure; some of it also enters the bloodstream; the level of osteocalcin in the blood reflects the rate of bone formation, thus it is a useful indicator of the function of osteoblasts. This test may be affected by use of the drug warfarin (Coumadin®).