Clinical usefulness of urinary CrossLaps as a sensitive marker of bone metabolism

Value of C-telopeptide-cross-linked Type I collagen, osteocalcin, bone-specific alkaline phosphatase and procollagen Type I N-terminal propeptide in the diagnosis and prognosis of bone metastasis in patients with malignant tumors

Background

Studies show markers of bone turnover can help the clinician in the diagnosis and follow-up of bone metastases. The present study aimed to investigate the value of biochemical markers of bone turnover in the diagnosis and prognosis of bone metastases of malignant tumors.

Material/Methods

The serum levels of C-Telopeptide-Cross-Linked Type I Collagen (CTx), Procollagen Type I N-Terminal Propeptide (PINP), Bone-Specific Alkaline Phosphatase (B-ALP) and Osteocalcin (OST) in patients with bone metastases and control subjects were measured using radioimmunoassay and immunochemiluminescent assay.

Results

The levels of CTx, PINP, B-ALP and OST in the metastasis group were significantly higher than those in both control groups and correlated with the number of bone metastatic sites. The levels of these markers were higher in prostate cancer patients with bone metastasis. The CTX of >426 ng/ml had the highest sensitivity and NPV, and PINP of >51.21 ng/ml had the highest specificity and PPV in healthy subjects. In addition, CTX of >547 ng/ml had the highest sensitivity and OST of >20.34 ng/ml the highest specificity in the non-metastasis group. Furthermore, both B-ALP of >15.55 ng/ml had relatively high negative predictive value and positive predictive value.

Conclusions

Biochemical markers of bone turnover, including CTx, PINP, B-ALP and OST, play important roles in the diagnosis and prognosis of metastatic bone cancer. CTX had a high sensitivity, and PINP had a high specificity in predicting bone metastasis. B-ALP is an ideal biochemical marker of bone turnover for metastatic bone cancer.

Bone resorption starts at 14 days of treatment with gonadotropin-releasing hormone agonist in in vitro fertilization cycles

The effect of gonadotropin-releasing hormone agonist (GnRH-a) use on bone turnover was investigated in a prospective cohort study of female patients undergoing in vitro fertilization (IVF) treatment. In 46 couples diagnosed with male-factor infertility, the women underwent a long step-down ovulation induction protocol. Urinary cross-linked N-telopeptide (uNTx) level was used to demonstrate bone turnover rate and was measured at the first day of GnRH-a administration, the first day of gonadotropin administration, the day after human chorionic gonadotropin injection and 12 days after embryo transfer. Urinary NTx levels (mean+/-standard deviation (SD)) were 71+/-34, 81+/-40, 81+/-50 and 83+/-47 nmol BCE/mmol creatinine (BCE, bone collagen equivalents), respectively. There was no statistically significant difference between the four measurements (p = 0.28). In 19 women GnRH-a was administered for > or = 14 days. Urinary NTx values of this group and the remaining 27 patients after GnRH-a treatment were 96.2+/-40.7 and 71.5+/-36.8 nmol BCE/mmol creatinine (mean+/-SD), respectively. The difference between these groups was statistically significant (p=0.038). These findings suggest that < 14 days' use of GnRH agonist in IVF patients has no effect on bone metabolism. To our knowledge, this is the first study demonstrating that the effect of agonists on bone metabolism starts as soon as estradiol suppression has started.

Low bone density and abnormal bone turnover in patients with atherosclerosis of peripheral vessels

Patients with vascular calcifications often have low bone mineral density (BMD), but it is still uncertain if osteoporosis and peripheral vascular disease (VD) are interrelated and linked by a common pathomechanism. Moreover, data on bone turnover in patients with advanced atherosclerosis are lacking. We measured BMD by dual-energy X-ray absorptiometry (DXA) and quantitative bone ultrasound (QUS), as well as the serum levels of osteocalcin (OC), bone-specific alkaline phosphatase (BAP), osteoprotegerin (OPG) and its ligand RANKL, and the urinary concentration of the C-terminal telopeptides of type I collagen (CrossLaps), in 36 patient (20 male and 16 female) with serious atherosclerotic involvement of the carotid and/or femoral artery to investigate the underlying mechanism of vascular and osseous disorders. Thirty age-matched and gender matched healthy individuals served as controls. After adjustment for age, BMD was significantly reduced at the lumbar spine in 23/36 (63%) patients (mean T score -1.71+/-1.42) and at the proximal femur in 34/36 (93%) patients (neck mean T score -2.5+/-0.88). Ten patients (27%) had abnormal QUS parameters. Gender and diabetes had no effect on the relationship between vascular calcification and bone density at any site measured. VD subjects had OC and BAP serum levels lower than controls (13.3+/-3.1 vs 27.7+/-3.3 ng/ml, P<0.01, and 8.4+/-2.3 vs 12.5+/-1.4 microg/l, P<0.01, respectively). Urinary CrossLaps excretion was not significantly different in patients with VD and in controls (257.9+/-138.9 vs 272.2+/-79.4 micro g/mmol Cr, respectively). Serum OPG and RANKL levels were similar in patients and in controls (3.5+/-1.07 vs 3.4+/-1.05 pmol/l, and 0.37+/-0.07 vs 0.36+/-0.06 pmol/l, respectively). We proved high occurrence of osteoporosis in VD, with evidence of age and gender independence. Negative bone remodelling balance would be a consequence of reduced bone formation, with no apparent increased activation of the OPG-RANKL system.

Urinary markers of type I collagen degradation in the dog

Urinary assays for type I collagen metabolites provide a non invasive index of bone resorption in humans, and are widely used in the management of patients with metabolic bone diseases. The specific aims of this study were to investigate the feasibility of using commercial human assay kits for quantifying the urinary excretion of type I collagen metabolites in dogs of different ages. Urine and serum samples were collected from 35 beagle dogs in five age groups (0 to 1 years; 1 to 2 years; 2 to 3 years; 3 to 7 years; > 8 years old). Urinary concentrations of pyridinoline (Pyd), deoxypyridinoline (Dpd), and the carboxy- and amino-terminal cross-linked telopeptides of type I collagen (CTx and NTx, respectively) were measured with commercial enzyme-linked immunoassay kits. Serum concentrations of another type I collagen metabolite, the carboxy-terminal cross-linked teloptide of type I collagen (ICTP), were measured with a commercial radioimmunoassay. Dilutional studies indicated that the four urinary assays show specific cross-reactivity with canine urine. Age-related differences in urinary marker excretion were identified, with young dogs excreting the highest concentrations of Pyd, Dpd, NTx and CTx. The correlation between the individual urinary markers was excellent (r = 0.87 to 0.98), while the correlation between serum ICTP and individual urinary markers was weaker (r = 0.52 to 0.64). These results validate the usefulness of the commercial assay kits in monitoring type I collagen metabolism in dogs. Histomorphometric studies have confirmed the relationship between collagen degradation and bone resorption in humans, and similar studies are now needed in dogs.

Estriol add-back therapy in the long-acting gonadotropin-releasing hormone agonist treatment of uterine leiomyomata

The hypoestrogenic state induced by gonadotropin-releasing hormone agonists (GnRHa) has been shown to be effective in the treatment of uterine leiomyomas but to induce bone loss. Estriol has been described to be a weak and short-acting estrogen without an increased risk of endometrial proliferation and hyperplasia. The purpose of this study was to evaluate whether treatment of uterine leiomyomata with GnRHa plus oral estriol add-back therapy could prevent bone loss, without deteriorating the therapeutic effect of GnRHa. Twelve premenopausal women with symptomatic uterine leiomyomas were randomized to receive either leuprolide acetate depot alone at a dose of 3.75 mg s.c. every month for 6 months (non add-back group; n = 6), or GnRHa for 6 months plus oral estriol 4 mg/day for 4 months commencing with the third GnRHa injection (add-back group; n = 6). In the add-back group, leiomyoma volume, as measured by transvaginal ultrasound, decreased to 59.1% of baseline at 2 months of GnRHa therapy with no significant change in size during the remaining treatment period. In contrast, it decreased to 31.3% of pretreatment size at the end of treatment in the non add-back group. The levels of bone metabolic markers such as CrossLaps, deoxypyridinoline, osteocalcin and bone-specific alkaline phosphatase, increased significantly throughout the treatment in the non add-back group, whereas they were suppressed by the add-back therapy. The bone mineral density of lumbar spine (L2-L4) as measured by dual-energy X-ray absorptiometry decreased significantly by 7.5% at the end of treatment in the non add-back group, but did not change significantly in the add-back group. In conclusion, GnRHa plus estriol add-back therapy might be considered for long-term treatment of uterine leiomyomata.

Establishment of permanent cell lines exhibiting vitamin D-dependent expression of beta-galactosidase activity

The active hormonal form of vitamin D3, 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3), has been described as a principal mediator of skeletal homeostasis. Treatment of rat osteosarcoma (ROS)17/2.8, an osteoblast-like cell line, with 1alpha,25(OH)2D3 results in a ligand-dependent increase in transcription of the bone-specific osteocalcin gene. We isolated permanent cell lines that were established by transfecting ROS 17/2.8 cells with plasmids consisting of the human osteocalcin gene promoter containing the vitamin D responsive element linked to a bacterial beta-galactosidase gene. In one of many cell lines, especially in clone NK-31, 1alpha,25(OH)2D3 strongly stimulated beta-galactosidase activity. Reverse transcription-polymerase chain reaction analysis also showed endogenous osteocalcin gene expression and beta-galactosidase gene expression in clone NK-31 cells, which paralleled the increase in beta-galactosidase activity. Using a synthetic analogue of 1alpha,25(OH)2D3, 24,24-difluoro-1alpha,25-dihydroxyvitamin D3, we found that the levels of this activity and these gene expressions were nearly parallel to those of 1alpha,25(OH)2D3. 24R,25-dihydroxyvitamin D3 and 25-hydroxyvitamin D3 at high doses (concentration: 10(-7) M) also induced beta-galactosidase activity in clone NK-31. These cell lines, harboring the plasmid-carrying beta-galactosidase gene under the control of the osteocalcin gene promoter, may contribute to studies on the regulation by 1alpha,25(OH)2D3 or to the development of synthetic analogues of 1alpha,25(OH)2D3.