Introduction
Oxidative stress induced by reactive oxygen species (ROS) is associated with the risk of osteoporosis, and can be reduced by certain dietary antioxidants. Lycopene is an antioxidant known to decrease the risk of age-related chronic diseases, such as cancer. However, the role of lycopene in osteoporosis has not yet been investigated.

Lycopene consumption decreases oxidative stress and bone resorption markers in postmenopausal women

This chapter reviews the recent development in bone marker technology and also discusses the use of markers for the management of osteoporosis. There are basically two types of biomarkers for bone remodelling: for bone formation and for bone resorption. Biomarkers for bone formation consists of skeletal alkaline phosphatase (ALP), osteocalcin, and procollagen type I propeptides (PICP). ALP activity may provide information of bone metabolism within specific bone envelopes. Serum total alkaline phosphatase activity is the most commonly used marker of bone formation, but for the above reasons, it lacks sensitivity and specificity. PICP concentrations correlate weakly with histological bone formation in patients with vertebral osteoporosis. Biochemical markers of bone resorption consists of tartrate-resistant acid phosphatase, free pyridinoline and deoxypyridinoline, C-terminal cross-linking telopeptide of type I, N-terminal and C-terminal (S-CTX) crosslinking telopeptide of type I collagen, and bone sialoprotein. In osteoporosis, bone turnover markers have been suggested to predict the rate of postmenopausal bone loss, to predict the occurrence of osteoporotic fractures, and to monitor the efficacy of treatment, especially anti-resorptive therapy (hormone replacement therapy, bisphosphonates, and calcitonin). It has also been suggested that measurement of bone turnover before treatment might be useful to select the type of therapy (anti-resorptive or bone stimulating agent) and to predict the amplitude of the response to estrogen and bisphosphonate treatment.

Biochemical markers of bone turnover in osteoporosis.

Disassociation of bone resorption and formation by GLP-2: a 14-day study in healthy postmenopausal women.

We measured bone mineral density (BMD), four markers of bone formation [bone alkaline phosphatase (bAP), osteocalcin (Oc), N- and C-terminal propeptide of type I procollagen (PINP and PICP respectively)] and five markers of bone resorption [serum C-terminal telopeptide of type I collagen (CTx), urinary CTx, N-terminal cross-linked telopeptide (NTx), free and total deoxypyridinoline (fDpd and tDpd respectively)] in 28 healthy premenopausal women (45.7 ± 3.0 years), 15 early ( LSC; n= 17/20). A significant change in serum CTx after 4 months of alendronate was the best predictor of a significant gain in spine BMD (i.e., ≥27 mg/cm2) after 1 year of therapy, allowing 15 of 16 patients (94%) to be classified correctly (one false-positive). Urinary NTx/Cr was the second best predictor. Despite a moderately high iCV (20.6%), serum CTx appeared the most effective of the markers tested and could be of interest for the detection of high bone turnover and the longitudinal monitoring of alendronate therapy in the individual patient. It must be stressed that serum PINP and urinary NTx and tDpd compared very similarly with serum CTx for monitoring alendronate therapy.

Differences in the capacity of several biochemical bone markers to assess high bone turnover in early menopause and response to alendronate therapy

A genetic contribution to bone mass determination was first described in the early 70s. Elucidation of gene contribution to this has since been attempted through studies analyzing associations between

Genetic determinants of bone mass.

A comparative study was performed on the sensitivity of the determination of the available biochemical markers of bone formation — total and bone alkaline phosphatase (TAP and bAP, respectively), osteocalcin (BGP), procollagen I aminoterminal propeptide (PINP) and procollagen I carboxyterminal propeptide (PICP) — in the study of postmenopausal osteoporosis. The comparison between PINP and PICP, due to the recent development of the amino-terminal assay, is of special interest. The study included 26 untreated osteoporotic postmenopausal women, age 59±6 years (range 46–69 years) and 17 healthy control postmenopausal women, age 56±7 years (range 48–70 years). We found a significant increase in the levels of bAP (p=0.0021), BGP (p=0.041), PINP (p=0.0001) and PICP (p=0.0073), but not in the levels of TAP (p=0.3389), in osteoporotic patients with respect to the control group. Serum PINP and bAP showed the highest diagnostic accuracy among the markers of bone formation studied, as can be deduced from the receiver operating characteristics (ROC) curves. In spite of their similar origin (amino-terminal and carboxy-terminal release from a procollagen molecule), the results obtained by measuring levels of PINP are significantly better than those found with PICP.

Biochemical markers of bone formation in the study of postmenopausal osteoporosis

BACKGROUND: Genetic factors condition an important part of bone mass. The role of vitamin D receptor polymorphism (VDR) as genetic marker of osteoporosis is a matter of discussion. We have studied the possible influence of VDR on bone remodelling, calciotropic hormones, on the presence of osteoporosis and osteoporotic bone fractures. PATIENTS, CONTROL POPULATION AND METHODS: A case-control study. We have studied a total of 127 postmenopausal Canarian women from Canary Islands, Spain; 66 healthy controls and 61 with the diagnosis of osteoporosis, which was made by clinical, radiological and densitometric criteria. 17 osteoporotic women have had a fracture: Colles, hip or vertebral (spinal deformity index) fracture. VDR were determined by PCR directed to demonstrate the presence (b) or absence (B) of a restriction target for Bsml in intron 7. We analyzed some biochemical markers of bone remodelling: serum levels of alkaline phosphatase, tartrate resistant acid phosphatase and urine ratios of calcium/creatinine and hydroxyproline/creatinine. We also determined calciotropic hormones: parathyroid hormone and calcitonin. Bone mass was measured by DEXA and TC. RESULTS: There were no significant differences in either biochemical bone remodelling markers or in bone mass between the three genotypes: bb, Bb and BB, either in controls or in osteoporotic women with the exception of alkaline phosphatase which had a significative increase compared to control in women with unfavorable alleles distribution (bB and BB). Distribution of genotypes was similar between controls and osteoporotic women, with or without fractures. CONCLUSIONS: In Canarian women, VDR genotype is not associated with changes in biochemical markers of bone remodelling or in bone mass or with the presence of osteoporosis or osteoporotic fractures.

Polimorfismo genético del receptor de la vitamina D y osteoporosis

Efecto de la administración crónica de estrógenos en varones transexuales sobre el metabolismo mineral óseo. Influencia del polimorfismo del receptor de la vitamina D.

C. Dominguez Cabrera

Papers

Biochemical markers of bone formation in the study of postmenopausal osteoporosis

Polimorfismo genético del receptor de la vitamina D y osteoporosis

Efecto de la administración crónica de estrógenos en varones transexuales sobre el metabolismo mineral óseo. Influencia del polimorfismo del receptor de la vitamina D.