Quantitation of urinary hydroxypyridinium cross-links from collagen by high-performance liquid chromatography

Rapid analysis of pyridinoline and deoxypyridinoline in biological samples by liquid chromatography with mass spectrometry and a silica hydride column

Pyridinoline and deoxypyridinoline crosslinks are biomarkers found in urine for collagen degradation in bone turnover. For the first time, a rapid, sensitive, and ion-pairing free method is described for the analysis of pyridinoline and deoxypyridinoline using ultra-high performance liquid chromatography with Cogent Diamond Hydride column and detection by Q Exactive hybrid quadrupole-orbitrap high resolution accurate mass spectrometry. The separation was achieved using both isocratic and gradient conditions and run time <5 min under isocratic conditions of 20% acetonitrile in water containing 0.1% formic acid. Pyridoxine was used as an internal standard and relative standard deviation of the retention times of both pyridinoline and deoxypyridinoline were <1%. The limit of detection was 0.082 ± 0.023 μM for pyridinoline and 0.118 ± 0.052 μM for deoxypyridinoline. The limit of quantitation was 0.245 ± 0.070 μM for pyridinoline and 0.354 ± 0.157 μM for deoxypyridinoline. The method was validated by the detection and quantitation of both pyridinoline and deoxypyridinoline in skin and urine samples.

Reference intervals of serum tartrate-resistant acid phosphatase type 5b activity measured with a novel assay in Japanese subjects

Among the isotypes of serum tartrate-resistant acid phosphatase (TRACP), only type 5b (TRACP-5b) is derived from osteoclasts, and it is necessary to develop an assay specific for this TRACP-5b for evaluation of osteoclastic activity. Recently, a novel assay system for TRACP-5b called the fragments absorbed immunocapture enzymatic assay (FAICEA) has been developed. With two unique monoclonal antibodies, one that is highly specific for TRACP-5b and another which absorbs inactive TRACP-5b fragments that interfere with measuring active TRACP-5b, this assay provides correct measurement of TRACP-5b activity in the serum without interference by the inactive fragments of TRACP-5b and other isotypes of TRACP, especially TRACP-5a. To study the reference data of Japanese subjects, we measured TRACP-5b activity in the serum of 320 men (age, 20-82 years) and 466 women [315 premenopausal (age, 18-55 years) and 151 postmenopausal (age, 45-77 years)] with this novel assay. In men, serum TRACP-5b activity did not vary significantly with age. The postmenopausal women had significantly higher serum TRACP-5b activity than the premenopausal women. The reference intervals (logarithmic mean +/-1.96 SD) for men, premenopausal women, and postmenopausal women were 1.7-5.9 U/l, 1.2-4.4 U/l, and 2.5-7.6 U/l, respectively.

Effect of cyclical intravenous clodronate therapy on bone mineral density and markers of bone turnover in patients receiving home parenteral nutrition

BACKGROUND

Patients receiving home parenteral nutrition (HPN) because of intestinal failure are at high risk of developing osteoporosis.

OBJECTIVE

We studied the effect of the bisphosphonate clodronate on bone mineral density (BMD) and markers of bone turnover in HPN patients.

DESIGN

A 12-mo, double-blind, randomized, placebo-controlled trial was conducted to study the effect of 1500 mg clodronate, given intravenously every 3 mo for 1 y, in 20 HPN patients with a bone mass T score of the hip or lumbar spine of less than -1. The main outcome measure was the difference in the mean percentage change in the BMD of the lumbar spine measured by dual-energy X-ray absorptiometry. Secondary outcome measures included changes in the BMD of the hip, forearm, and total body and biochemical markers of bone turnover, ie, serum osteocalcin, urinary pyridinoline, and urinary deoxypyridinoline.

RESULTS

The mean (+/-SEM) BMD of the lumbar spine increased by 0.8 +/- 2.0% in the clodronate group and decreased by 1.6 +/- 2.0% in the placebo group (P = 0.43). At all secondary skeletal sites (ie, hip, total body, and distal forearm), we observed no changes or small increases in the BMD of the clodronate group and decreases in the BMD of the placebo group. In the clodronate group, biochemical markers of bone resorption decreased significantly (P < 0.05).

CONCLUSIONS

Clodronate significantly inhibits bone resorption as assessed by changes in biochemical markers of bone turnover. Although the mean BMD increased in the clodronate group, cyclic clodronate therapy failed to increase spinal BMD significantly at 12 mo.

Bone mineral content and bone metabolism in young adults with severe periodontitis

OBJECTIVES

To clarify in young adults with severe periodontitis (1) whether the bone mineral content (BMC) or density (BMD) in the mandible/other skeletal sites and the systemic bone metabolism differed from normal and (2) whether mandibular/forearm BMC did change during the 5 to 10-year follow-up.

MATERIAL AND METHODS

24 young otherwise normal patients with verified severe periodontitis were included, of which 20 attended the follow-up visit. Mandibular/forearm BMC was measured at both visits by dual-photon absorptiometry, supplemented with femoral neck/lumbar spine BMD measurements at follow-up visit by dual-energy X-ray absorptiometry. Serum alkaline phosphatase/ionized calcium, urinary excretion of pyridinoline/deoxy-pyridinoline were analysed at the follow-up visit. A conventional periodontal examination was performed at both visits.

RESULTS

Mandibular BMC was significantly below normal mean BMC at both visits. The mandibular Z-scores were < or = -2.00 in 33.3% (8/24). BMC/BMD in the remaining sites and the values for bone markers did not differ from normal. Mandibular/forearm BMC was stable while a significant aggravation of alveolar bone loss occurred during the trial without change of probing depth.

CONCLUSIONS

Severe periodontitis in young adults seems to be a local disorder associated with relatively low BMC in the jaws without systemic alterations of BMC/BMD and bone metabolism.

Bone minerals changes in obese women during a moderate weight loss with and without calcium supplementation

A significant relationship between body weight (BW) and bone mass (BM) has been established previously. A diet-induced weight loss is accompanied by a significant decrease in bone mineral density (BMD) and total body bone mineral (TBBM), but the underlying mechanisms are not clarified. Sixty-two obese women were included in the study. Dual-energy X-ray absorptiometry (DXA) and measurements of a series of calcium-regulating hormones and biochemical markers of bone turnover were performed at baseline and after 1 month and 3 months on a low calorie diet. Thirty of the women were randomized to a daily supplement of 1 g of calcium. After an additional 3 months without dietary prescriptions or calcium supplements, a subgroup of 48 subjects (24 from each group) were scanned again using DXA. There was a significant decrease in TBBM after 1 month and 3 months. A similar pattern was observed in the bone mineral content (BMC) of the lumbar spine in the patients who did not receive a calcium supplement, whereas no changes occurred in the supplemented group. The initial calcium supplementation seemed to protect against bone loss in the lumbar spine but not in the TBBM. In the nonsupplemented group, a statistically significant inverse correlation was found between the calcium/creatinine ratio in the morning urine and the changes in BMC of the lumbar spine. Such a relationship was not seen in the calcium-supplemented group. In the nonsupplemented group, no significant biochemical changes were observed, whereas a significant decrease in serum parathyroid hormone (PTH) was seen in the calcium-supplemented group. This might explain some of the protective effects of calcium supplementation on trabecular bone mass. We conclude that a diet-induced weight loss is accompanied by a generalized bone loss, which probably is explained mainly by a reduced mechanical strain on the skeleton. This loss can be partly inhibited by a high calcium intake. Therefore, a calcium supplementation should be recommended during weight loss, even if the diet contains the officially recommended amounts of calcium.

Alendronate increases lumbar spine bone mineral density in patients with Crohn's disease

BACKGROUND & AIMS

Low bone mineral density (BMD) is a common complication of Crohn's disease and may lead to increased morbidity and mortality because of fractures. We investigated the effect of treatment with the bisphosphonate alendronate on bone mass and markers of bone remodeling in patients with Crohn's disease.

METHODS

A 12-month double-blind, randomized, placebo-controlled trial examined the effect of a 10-mg daily dose of alendronate. Thirty-two patients with a bone mass T score of -1 of the hip or lumbar spine were studied. The main outcome measure was the difference in the mean percent change in BMD of the lumbar spine measured by dual-energy x-ray absorptiometry. Secondary outcome measures included changes in BMD of the hip and total body and biochemical markers of bone turnover (S-osteocalcin, urine pyridinoline, and urine deoxypyridinoline excretion).

RESULTS

Mean (+/-SEM) BMD of the lumbar spine showed an increase of 4.6% +/- 1.2% in the alendronate group compared with a decrease of 0.9% +/- 1.0% in patients receiving placebo (P < 0.01). BMD of the hip increased by 3.3% +/- 1.5% in the alendronate group compared with a smaller increase of 0.7% +/- 1.1% in the placebo group (P = 0.08). Biochemical markers of bone turnover decreased significantly in the alendronate group (P < 0.001). Alendronate was well tolerated, and there was no difference in adverse events among treatment groups.

CONCLUSIONS

Treatment with alendronate, 10 mg daily, significantly increased BMD in patients with Crohn's disease and was safe and well tolerated.

Relationships between bone mineral density, serum vitamin D metabolites and calcium:phosphorus intake in healthy perimenopausal women

OBJECTIVES

To determine the relationships between serum vitamin D metabolites, bone mass, and dietary calcium and phosphorus in a cohort of 510 healthy Danish perimenopausal women.

DESIGN

A population-based cross-sectional study.

SUBJECTS

A total of 510 healthy women aged 45-58 years, with amenorrhoea for 3-24 months. None of the women was using hormone replacement therapy.

MEASUREMENTS

Measurements of total bone mineral content and regional bone mineral density were performed by dual-energy X-ray absorptiometry. Analyses of serum levels of 25-OHD and 1,25-(OH)2D, intact PTH, ionized calcium and phosphate, as well as biochemical markers of bone turnover in blood and urine. Assessment of calcium and phosphorus intake using dietary records.

RESULTS

A consistent inverse relationship between serum 1,25-(OH)2D and bone mineral content/ density was found in whole-body mineral content (P = 0.001), spine (P = 0.005) and femoral neck (P<0.05). There was a positive relationship between levels of 1,25-(OH)2D and biochemical bone markers, indicating that high levels of 1,25-(OH)2D are accompanied by increased bone turnover. The dietary calcium:phosphorus ratio was inversely related to serum 1,25-(OH)2D (P = 0.04) and positively related to bone mineral density (P<0.0005). No relationships could be detected between levels of PTH, serum ionized calcium and phosphate, and serum vitamin D metabolites.

CONCLUSION

Within normal physiological range, elevated levels of 1,25-(OH)2D were associated with decreased bone mineral density and content, reduced calcium:phosphorus ratio in the diet and increased bone turnover.

The effect of chronic hexarelin administration on the pituitary-adrenal axis and prolactin

OBJECTIVE

With the development of growth hormone (GH) releasing agents and their use in human subjects, it is clear that these agents are not specific for GH release. More recent studies in humans have demonstrated acute increases in adrenocorticotrophic hormone (ACTH), cortisol and prolactin (PRL) after boluses of intravenous or subcutaneous GHRPs. The potential adverse effects of repeated episodes of transient hyperprolactinaemia and hypercortisolaemia during long-term therapy with growth hormone releasing peptides (GHRPs) and similar agents have raised concern. We have therefore assessed the impact of chronic hexarelin administration on the pituitary-adrenal axis and serum prolactin levels.

DESIGN

Each subject received twice-daily subcutaneous hexarelin therapy (1.5 micrograms/kg body weight) for 16 weeks. The ACTH, cortisol and PRL responses to the morning subcutaneous injection of hexarelin were assessed. Hexarelin was administered at time 0 and blood samples were taken at -10, 0, 10, 20, 30, 40, 50, 60, 90, 120, 170 and 180 min. The ACTH and PRL responses were assessed at baseline and after 16 weeks of therapy. The cortisol response was assessed at baseline, 16 weeks and also 4 weeks after completion of hexarelin therapy. Basal levels of cortisol binding globulin (CBG), 24-h urinary free cortisol (UFC) estimations, thyroid stimulating hormone (TSH) and total thyroxine (TT4) were performed at baseline, weeks 16 and 20.

RESULTS

The mean (+/- SEM) area under the cortisol curve (AUCCORT) at baseline, week 16 and week 20 were 1506 (+/- 77) nmol/l/h, 1222 (+/- 92) nmol/l/h and 1586 (+/- 58) nmol/l/h, respectively. There was a significant change in AUCCORT over the study period (P = 0.008). Compared with baseline, AUCCOPRT had decreased significantly (P < 0.05) after 16 weeks of hexarelin therapy. Four weeks after completion of hexarelin therapy, the AUCCORT increased significantly compared with AUCCORT at week 16 (P < 0.01) and was no longer significantly different from baseline values. There were no significant changes in UFC (P = 0.3), basal cortisol measurements (P = 0.19), area under the ACTH curve (AUCACTH) (P = 0.24) or CBG (P = 0.6) over the study period. The mean (+/- SEM) area under the PRL curve (AUCPRL) at the baseline and week 16 were 624 (+/- 82) mU/l/h and 641 (+/- 83) mU/l/h, respectively. There was no significant change in AUCPRL over the study period (P = 0.35).

CONCLUSION

The present study demonstrates clearly that in this hexarelin dosage regimen, over-stimulation of the pituitary adrenal axis and prolactin secretion do not occur. In fact the impact of chronic hexarelin therapy on the pituitary-adrenal axis, i.e. decreased AUCCORT, contradict the findings reported after acute hexarelin administration and cannot be explained by changes in CBG. The lack of change in UFC, however, suggests that these changes are unlikely to be of clinical significance although the underlying mechanism requires further study.

Adverse effects of inhaled budesonide (800 micrograms) on growth and collagen turnover in children with asthma: a double-blind comparison of once-daily versus twice-daily administration

BACKGROUND

Twice-daily administration of inhaled budesonide (400 micrograms) suppresses short-term growth in children with asthma.

OBJECTIVE

To compare short-term growth and markers of collagen turnover during treatment with 800 micrograms of inhaled budesonide administered once daily in the morning and 400 micrograms administered twice daily.

PATIENTS

Twenty-four children with asthma aged 5.6 to 12.5 years.

SETTING

An outpatient secondary referral center.

METHODS

A randomized, double-blind, crossover trial with 2 treatment periods of 4 weeks was conducted, and growth was assessed with a knemometer. The carboxy terminal propeptide of type I procollagen, the amino terminal propeptide of type I procollagen (PINP), the carboxy terminal pyridinoline cross-linked telopeptide of type I collagen, the amino terminal propeptide of type III procollagen (PIIINP), and urinary pyridinoline and deoxypyridinoline were evaluated.

RESULTS

Mean lower leg growth rate (P = .04), PINP (P = .03), and PIIINP (P < .01) were suppressed during twice-daily administration of budesonide, 400 micrograms. Otherwise, no statistically significant differences were detected.

CONCLUSIONS

As compared with 400 micrograms of inhaled budesonide administered twice daily, 800 micrograms administered once daily in the morning has a sparing effect on short-term growth and collagen turnover.

Thyroid hormone treatment aiming at reduced, but not suppressed, serum thyroid-stimulating hormone levels in nontoxic goitre: effects on bone metabolism amongst premenopausal women

OBJECTIVES

To study the effects of six months' treatment with either T4 or T3, aiming at reduced but not totally suppressed serum TSH levels, as measured by a third generation TSH assay, on biochemical bone turnover parameters as well as bone mass in patients with nontoxic goitre.

DESIGN

Prospective randomized study with a matched control group, not blinded.

SETTING

Two University Hospital Clinics in Copenhagen.

SUBJECTS AND INTERVENTION

Twenty-four consecutive premenopausal women with moderate sized nontoxic goitre. Fourteen patients randomized to T4 or T3 treatment for six months with monthly titration of the dose, aiming at TSH values between 0.005 and 0.2 mUL(-1). Ten controls.

MAIN OUTCOME MEASURES

Serum parathyroid hormone (PTH), serum procollagen I C-terminal propeptide (PICP), serum alkaline phosphatase, serum osteocalcin, u-pyridinoline, u-deoxypyridinoline, u-hydroxyproline. Bone mass (BMD) at the lumbar spine and at both femoral necks.

RESULTS

Serum TSH was generally kept within the desired interval. There was no difference in any marker of bone metabolism between the effects of T4 and T3. Consequently, these groups were combined in order to evaluate the effect of thyroid hormones on the bone and mineral metabolism. Thyroid hormone treatment resulted in increased levels of serum ionized calcium (Ca) (P=0.02), serum alkaline phosphatase (P=0.007), serum-PICP (P=0.003), serum osteocalcin (P=0.02) and urinary excretion of deoxypridinoline (P=0.03) compared to untreated controls. Bone mass did not change.

CONCLUSION

Six months treatment with either T4 or T3 of premenopausal women with nontoxic goitre, aiming at reduced but not totally suppressed TSH values, resulted in biochemical signs of increased bone turnover, whereas bone mass remained unaltered. No differences were found between the effects of T4 or T3 treatment.

Sensitive fluorimetric quantitation of pyridinium and pentosidine crosslinks in biological samples in a single high-performance liquid chromatographic run

A high-performance liquid chromatographic assay was developed for pyridinium crosslinks and pentosidine in mature collagen of a wide variety of connective tissue hydrolysates by a simple two-step isocratic assay using a reversed-phase column. The crosslinks (including the internal standard pyridoxine) were optimally detected by their native fluorescence by switching wavelengths of the detector during the assay. The method resulted in highly sensitive and accurate measurements, without need for precleaning of the samples: crosslink levels in 200 microm thin slices of the various zones of articular cartilage were easily quantified. The detection limit was as low as 0.4 pmol for the pyridinolines and 0.05 pmol for pentosidine. The intra-assay and inter-assay coefficients of variation were as low as 2% (pyridinolines) and 5% (pentosidine); calibration curves for all compounds were linear over a concentration range larger than two orders of magnitude. With our chromatographic system, the diglycosylated form of hydroxylysylpyridinoline in unhydrolyzed urine was separated as well.

Short-term growth and collagen turnover in asthmatic adolescents treated with the inhaled glucocorticoid budesonide

Short-term lower leg growth, the insulin-like growth factor axis, and collagen turnover were assessed in 16 adolescents with asthma during treatment with inhaled budesonide, 800 micrograms/d, from a pressurized metered dose inhaler with a volume spacer. The design was a randomized double blind, placebo-controlled two-period crossover trial with treatment periods of 4 weeks and a 1-week wash-out. Lower leg growth was assessed by knemometry. Serum levels of insulin-like growth factor-I, insulin-like growth factor-binding protein-3, and the following markers of collagen turnover were evaluated: Serum markers of type I collagen formation and degradation; the carboxy-terminal propeptide of type I procollagen and the carboxy terminal pyridinoline cross-linked telopeptide of type I procollagen (ICTP), the serum marker of type III collagen formation; the amino-terminal propeptide of type III procollagen (PIIINP) and the urinary concentrations of the type I collagen degradation products pyridinoline (PYD) and deoxypyridinoline (DPD) cross-links. Mean lower leg growth velocity was suppressed from 0.51 mm/week during placebo to 0.18 mm/week during budesonide treatment (p < 0.001). No statistically significant effects on insulin-like growth factor-1, insulin-like growth faster-binding protein-3, or carboxy-terminal propeptide of type I procollagen were observed. ICTP and PIIINP were reduced with 2.3 and 2.5 micrograms/liter (p < 0.001 and p < 0.001, respectively) during budesonide treatment, urinary concentrations of PYD and DPD with 32.9 nmol/mmol creatinine (p < 0.005) and 6.8 nmol/mmol creatinine (p < 0.005), respectively. Significant correlations between lower leg growth velocity and ICTP, PIIINP, PYD, and DPD during placebo (p < 0.01, p < 0.05, p < 0.01, and p < 0.01) and budesonide (p < 0.05, p < 0.05, p < 0.05, and p < 0.05) periods were found. Short term lower leg growth suppression in adolescents treated with inhaled budesonide, 800 micrograms/d, reflects suppression of type I and III collagen turnover.

Assessment of different markers of bone resorption in postmenopausal osteoporotic women treated with pamidronate

The aim of this study was to evaluate the different bone resorption markers, total pyridinoline (Pyr) and total deoxypyridinoline (Dpyr), assessed by a HPLC method, free Dpyr, assessed by a new immunoassay, and urinary excretion of hydroxyproline (OH-proline), in postmenopausal osteoporotic women during long-term treatment with pamidronate. A total of 60 postmenopausal women with previous distal forearm fracture were included in this 12-month placebo-controlled and double-blind study, where intermittent oral pamidronate, 75 or 150 mg, or placebo were given daily for 4 weeks, every 16 weeks. After 1 week a significant reduction in urinary excretion of total Dpyr was observed in the group treated with 150 mg pamidronate compared to the placebo (p < 0.01) and to the 75-mg group (p < 0.001). A maximal 50.4% decrease in total Dpyr, (p < 0.0001 compared to the placebo group, p < 0.01 compared to the 75-mg group), was observed after 3 weeks of treatment with 150 mg pamidronate, and this decrease persisted to week 52. After 4 weeks of treatment with 150 mg pamidronate the maximal decrease in free Dpyr was only 26.5%, which persisted during 12 months of treatment. Decreases in urinary excretion of total Pyr and OH-proline were less than the decreases in total Dpyr. The correlation between total Dpyr (HPLC method) and free Dpyr (Pyrilinks-D assay) at baseline was r = 0.91. Total Dpyr assessed by the HPLC method reflects the pamidronate-induced decrease in bone resorption, and the changes in this resorption marker were more pronounced than changes in free Dpyr, total Pyr and OH-proline. In this study free Dpyr analysis was less suitable for reflecting bone resorption during bisphosphonate therapy.

A single measurement of biochemical markers of bone turnover has limited utility in the individual person

Biochemical markers of bone turnover are used to estimate the rate of bone loss in the individual osteoporotic patient. During recent years it has become increasingly clear that the biological variability of biochemical bone markers has to be taken into consideration in the evaluation of their usefulness in the clinical setting. Eleven premenopausal, 8 perimenopausal and 11 postmenopausal healthy women were included. We assessed the analytical and the biological components of variation for a number of resorptive and formative bone markers: u-hydroxyproline, u-pyridinoline, and u-deoxypyridinoline together with u-calcium and u-creatinine, s-total alkaline phosphatases and s-osteocalcin. Blood and urine samples were collected five times with 7-day intervals. Urinary parameters were expressed as outputs and corrected for creatinine in fasting night urines and second void fasting morning urines. The absolute values differed with a tendency towards increasing values in the postmenopausal women, but the biological variations in relation to menopausal status were not different. The biological variability was much higher for the urinary resorptive markers than for the formative markers in the blood. The critical difference expressing the difference needed between two serial results from the same person to be significant at a 5% level was 15% for s-alkaline phosphatases, 18% for s-osteocalcin, and lowest in the second void fasting morning urines with values of 28% and 34% for u-pyridinoline/creatinine and u-deoxypyridinoline/creatinine, and 50% and 112% for u-hydroxyproline/creatinine and u-calcium/creatinine, respectively. The index of individuality, denoting the individual variation divided by the variation between subjects, was in the range from 0.19 for s-alkaline phosphatases to 1.23 for u-hydroxyproline/minute in second void fasting morning urine making the use of conventional reference intervals difficult. Low indices, however, indicate high test performance and offer the possibility of stratification of persons within a range. The number of samples required to determine the true individual mean value +/- 5% for the single person, ranged from 5 for s-total alkaline phosphatases, 6 for s-osteocalcin, 23 for u-deoxypyridinoline/creatinine in the fasting morning urine to over two hundred for u-calcium analytes. It is concluded that, due to high biological variation, a single measurement of biochemical markers of bone turnover is of limited utility in the individual person. We recommend that routine clinical use of biochemical markers should be restricted until further evidence justifies it.

Serum and urinary markers of types I and III collagen turnover during short-term prednisolone treatment in healthy adults

During recent years new sensitive serum and urinary makers have been introduced for assessment of collagen turnover. The aim of the present study was to assess whether short-term prednisolone treatment is associated with any adverse effects on serum levels of the type I collagen synthesis marker, the carboxy terminal propeptide of type I procollagen (PICP); on the type I collagen degradation marker in serum, the carboxy terminal pyridinoline cross-linked telopeptide of type I collagen (ICTP); on a serum marker of type III collagen synthesis, the aminoterminal propeptide of type III procollagen (PIIINP), or on the type I collagen degradation markers urinary pyridinoline (PYD) and deoxypyridinoline (DPD) concentrations. We studied 12 men and 8 premenopausal women aged 19-45 years (mean 31). All subjects were healthy. The design was a randomized double-blind, placebo-controlled parallel group study with a 2-day run-in, a 3-day treatment period and a 4-day run-out. During run-in and run-out no medication was given. During the treatment period the subjects took either prednisolone, 40 mg per day, or placebo. Blood and urine were collected at the last day of each period. The intergroup comparisons of run-in treatment values showed that prednisolone suppressed PICP (p < 0.001) and PIIINP (p < 0.001). PICP levels remained suppressed during run-out, whereas PIIINP returned to pretreatment levels. NO prednisolone-induced effects on ICTP or on urinary PYD or DPD were detected by the intergroup comparisons. Short-term prednisolone treatment is associated with suppressive effects on type I and III collagen turnover. Whether serum PICP is more sensitive than urinary PYD and DPD for detection of short-term suppressive effects on type I collagen turnover remains to be further evaluated.

Effect of nasal salmon calcitonin on bone remodeling and bone mass in postmenopausal osteoporosis

The effect of nasal salmon calcitonin (SCT) on bone has been investigated by densitometry, biochemical markers of bone turnover, and histomorphometry. 62 women (mean age 65 years) who had experienced Colles' fracture after menopause were randomized to receive either nasal salmon calcitonin (SCT) 200 IU or nasal placebo daily for 24 months. All received a daily supplement of 0.5 g calcium. There was a significant increase above baseline in the bone mineral density of the lumbar spine in the SCT group (2.5%; 95% confidence interval 0.9--4.2%) and in the placebo group (1.7%; 95% confidence interval 0.3--3.1%) after 24 months, but the difference between the groups was not significant (0.8%; 95% confidence interval -1.2-3.0%). Serum levels of osteocalcin decreased significantly below baseline in the SCT group, whereas they were unchanged in the placebo group. At months 12 and 24, serum levels of osteocalcin were significantly lower in the SCT group than in the placebo group (p < 0.03). Urinary levels of deoxypyridinoline/creatinine decreased significantly below baseline in the SCT group, whereas only a transient decrease was observed in the placebo group. The differences between the groups were, however, not significant. The erosion depth was significantly lower in the SCT group than in the placebo group after 12 months (median [interquartile range]; 46.9 mu m [10.4] vs. 50.5 mu m [10.7]; p = 0.03), whereas bone volume and activation frequency did not differ between the groups. This study indicates that nasal SCT in a dose of 200 IU daily induces only a minor inhibition of bone resorption and therefore produces only a minor increase in bone mass. Furthermore, it seems that nasal SCT in a dose of 200 IU does not interfere with the recruitment of new bone multicellular units, but preferably decreases ongoing osteoclastic bone resorption.

Biological variation in urinary excretion of pyridinium crosslinks: recommendations for the optimum specimen

We assessed the analytical and biological variation of pyridinium crosslinks in early morning, 2 h fasting, and 24 h urine specimens from 14 healthy adults over a 1 month period. The results were expressed both in terms of pyridinoline concentration and pyridinoline/creatinine ratio. The data obtained were used to select the optimum specimen for clinical purposes. We found that: (a) early morning specimens are preferred; (b) results should be expressed as pyridinoline/creatinine ratio; (c) reference intervals should be stratified according to gender; (d) the necessary analytical imprecision (CV < or = 9%), derived from biological variation, is not easily achieved by current methods; (e) the difference between serial results from an individual must be > 50% to be statistically significant; and (f) assessment of risk for osteoporotic fracture by means of the pyridinium crosslink assay would, in a significant number of patients, require analysis of multiple urine specimens.

Effects of salmon calcitonin suppositories on bone mass and turnover in established osteoporosis

The objective of this study was to test the efficacy and safety of salmon calcitonin (sCT) suppository in post-menopausal women with previous hip fractures as an inhibitory agent of bone loss. The study was a single blind, randomized, and placebo-controlled trial comparing three parallel groups of patients. Fifty-four healthy women were randomly allocated to 1 year's treatment with either sCT 100 IU/6 times a week, 200 IU/3 times a week, or placebo/6 times a week. All groups received a calcium supplement of 500 mg daily. Fifteen patients left the study before its end, six of those due to adverse events, such as abdominal and rectal pain, nausea, headache, and diarrhea. Bone mineral density of the spine and the femoral neck was measured every 26 weeks, and biochemical markers of bone turnover were measured at baseline and week 12, 26, and 52. There were no significant changes in bone mineral density in the spine and in the hip in any of the treatment groups. No significant changes were observed in serum alkaline phosphatase, serum osteocalcin, urine hydroxyproline, and urine pyridinoline or deoxypyridinoline. Conclusively, we did not observe any significant effect on bone metabolism in women with postmenopausal osteoporosis after 1 year of treatment with sCT suppositories at the doses used.

Acute effects of nasal salmon calcitonin on calcium and bone metabolism

Effects of a single dose of 200 IU of nasal salmon calcitonin (SCT) on calcium metabolism and biochemical markers of bone turnover were investigated in 12 healthy male volunteers in a randomized, placebo-controlled, cross-over design. The nasal spray was given in the morning, and subsequently blood and urine samples were collected for 26 hours. There was a significant decrease in serum ionized calcium with a nadir 4 hours after administration of nasal SCT accompanied by a significant increase in serum parathyroid hormone (P = 0.01) and serum calcitriol (P = 0.04). Nasal SCT did not reduce urinary hydroxyproline/creatinine. Urinary deoxypyridinoline/creatinine was lowered significantly 2 hours after administration of nasal SCT and throughout the first 24 hours, but remained unchanged for the last 2 hours. On a 24-hour basis, urinary deoxypyridinoline/creatinine decreased from 14.1 (3.5) nmol/mmol to 11.7 (3.2) nmol/mmol after nasal SCT (P = 0.04). Nasal SCT did not change the serum levels of alkaline phosphatase, osteocalcin, and the carboxyterminal propeptide of type 1 procollagen. The results indicate that nasal SCT given as a single dose provokes a modest decrease in bone resorption lasting several hours, but leaves bone formation unaffected.