Biochemical markers in the follow-up of the osteoporotic patients.

Osteoporosis, a disease characterised by low bone mass and micro-architectural deterioration of bone tissue, is viewed as an emerging medical condition. Bone mineral density (BMD) is considered the gold standard of bone status assessment, however it does not offer the timely response desirable for monitoring. Biochemical markers of bone turnover (BTMs) are claimed to be suitable for that purpose. There is not generalized agreement on which marker could be used in routine. The present paper reviews pros and cons of currently used BTMs and relative analytical methods. Several analytical issues, such as biological variability, molecules stability, lack of reference materials jeopardize the field and, consequently, recommendations are difficult to be drawn. Reference range can't be used to support clinical judgement and, in this view, Least Significant Change (LSC) is regarded as a way to improve the interpretation of analytical results.Bone alkaline phosphatase (bALP) is still a marker of interest and its use is widespread in clinical laboratories; Tartrate Resistant Acid Phosphatase band 5b (TRAP 5b) appears to be a promising marker. N-terminal propeptides of type I collagen (s-PINP) and beta-collagen 1 C-terminal cross linked telopeptides (s-CTX), given low biological variability and assay availability for automatised instruments, should be the marker of choice in future clinical trials, to overcome the paucity of uniform data and should be used in clinical routine, to monitor osteoporosis treatment. Finally, the lack of standardisation of currently available diagnostic methods, could be overcome by harmonisation.