Serum osteocalcin, total and bone-specific alkaline phosphatase following isolated tibial shaft fracture

We report the changes in osteocalcin concentrations and in total and bone specific alkaline phosphatase activity occurring in the twenty week period following tibial shaft fracture in 20 subjects. Bone formation during the healing process is reflected by progressive increases in the concentration of osteocalcin and bone specific alkaline phosphatase after week 5 and the latter correlated with the height and weight of the subject. In the early post injury period, total alkaline phosphatase activity increased whereas that of the bone isoenzyme initially fell, starting to rise again during the second week. After an immediate post injury rise, osteocalcin concentration also decreased, reaching a nadir by week 5. As only three of our subjects demonstrated delayed union, we have not been able to demonstrate that biochemical monitoring of the healing process can provide an indication of prognosis in tibial shaft fracture.

New and traditional serum markers of bone metabolism in the detection of skeletal metastases

OBJECTIVES

The evaluation of "new" and "traditional" markers of osteoblastic and osteoclastic activity, in patients with bone metastases.

DESIGN AND METHODS

Our series consist of 40 patients with clinical, radiological, and scintigraphic evidence of bone metastases, and 40 age-matched healthy subjects. In all samples, traditional markers were evaluated by measuring total alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TrACP) activity, and osteocalcin (BGP) concentration. To assess new biochemical bone markers, bone isoenzyme of alkaline phosphatase (ALP-B) activity, carboxyterminal propeptide of type I procollagen (PICP), and carboxyterminal telopeptide of type I collagen (ICTP) concentrations were measured.

RESULTS

Our findings showed that the best diagnostic efficiency is provided by ICTP (0.94) followed by total ALP (0.90), ALP-B (0.80), and TrACP (0.76). The efficiency of BGP and PICP was, instead, very low (0.64 and 0.60, respectively).

CONCLUSION

Our results confirm the utility of the new serum markers such as ALP-B and ICTP assays in detecting bone metastases.

Bone and collagen turnover during treatment with inhaled dry powder budesonide and beclomethasone dipropionate

OBJECTIVES

To assess bone and collagen turnover in asthmatic children treated with dry powder budesonide from the Turbuhaler and dry powder beclomethasone dipropionate from the Diskhaler in a dose of 800 micrograms/day.

SUBJECTS

Thirteen prepubertal children with asthma.

DESIGN

Open crossover study with two treatment periods and treatment free run-in and wash-out periods. All periods were of two weeks' duration. At day 14 in each period blood samples were taken for assessment of serum osteocalcin, the carboxyterminal propeptide of type I collagen (PICP), and the aminoterminal propeptide of type III collagen (PIIINP). At the same time urine was collected for assessment of creatinine corrected pyridinoline (uPYR/cr) and deoxypyridinoline (udPYR/cr) crosslinks.

RESULTS

Osteocalcin concentrations were not influenced by any of the treatments. During budesonide treatment mean (SEM) PICP was reduced by 18% (8%) (p = 0.03), PIIINP by 24% (3%) (p = 0.0002), uPYR/cr by 16% (6%) (p = 0.03), and udPYR/cr by 21% (13%) (p = 0.12). During treatment with beclomethasone dipropionate mean (SEM) PICP was reduced by 20% (6%) (p = 0.01), PIIINP by 36% (3%) (p = 0.0002), uPYR/cr by 18% (4%) (p = 0.004), and udPYR by 13% (5%) (p = 0.02). The suppressive effect of beclomethasone dipropionate on PIIINP was more marked than that of budesonide (p = 0.001).

CONCLUSION

Treatment with dry powder budesonide and beclomethasone dipropionate 800 micrograms/day is associated with suppression of bone and collagen turnover. The suppression seems to be more marked during treatment with beclomethasone dipropionate. Long term effects and effects of lower doses of budesonide and beclomethasone dipropionate on bone and collagen markers needs further study.

Biological variation in bone-derived biochemical markers in serum

Analytical, within-subject and between-subject components of variation have been determined for total alkaline phosphatase (ALP) and its bone isoform, osteocalcin, and tartrate-resistant acid phosphatase (TR-ACP) in serum specimens from a cohort of 10 healthy subjects over a 1-month period. From these data, we have calculated the desirable analytical imprecisions, the indices of individuality, the critical differences for significant change detection, and the number of specimens required to estimate the homeostatic setpoint of an individual. For total ALP and its bone isoform, most of the observed variability was biologic, whereas osteocalcin and TR-ACP also had relatively high analytical variability. Total and bone ALP were also the parameters showing the lowest within-subject variability, whereas TR-ACP showed the lowest interindividual fluctuation. Osteocalcin and bone ALP had marked individuality, showing that the use of population-based reference limits is inadequate for their interpretation. The applicable differences required for two results to be significantly different (p < or = 0.05) are bone ALP: 20%; osteocalcin: 29%; and TR-ACP: 35%. The results demonstrate that the biochemical markers of bone turnover studied are of limited use to screen for metabolic bone disorders, but can be useful adjuncts for monitoring groups of patients in longitudinal studies.

Biochemical bone markers compared with bone density measurement by dual energy X-ray absorptiometry

In contrast to medical imaging, the biochemical markers allow a more frequent determination and are not as invasive as histomorphometric methods. We investigated biochemical markers of type I collagen compared with bone density measurements in 85 females between 41 and 89 years of age (median: 57 years). The bone density measurements were performed by dual energy X-ray absorptiometry (DXA) on the lumbar spine (L1-4). The bone density measurements were stated as a percentage of the norm. All patients were divided into three groups: I = <80%; II = 80-130%; III = >120%. Based on this classification the median concentration of the I-carboxyterminal propeptide of type I collagen in serum (S-PICP) as an anabolic marker of type-I collagen increased significantly with rising bone density: I 65.0 micrograms/liter (interquartile range: 52.1-78.0 micrograms/liter); II 85.9 micrograms/liter (52.1-115.5 micrograms/liter); III 81.4 micrograms/liter (62.0-101.0 micrograms/liter);P < 0.05. The concentration of urinary pyridinolines (U-PYR) as a marker for degradation of type I collagen decreased. The I-carboxyterminal telopeptide (S-ICTP) and osteocalcin (S-BGP) did not change. The multivariate regression analysis showed no relationship between between bone density and biochemical bone markers. Only the age significantly correlated negatively with bone density measurement. For a better assessment of type I collagen metabolism we created a "b-quotient" by dividing the sum of S-PICP and S-BGP by U-PYR. The median b-quotient increased significantly: I 1.55 (0.97-2.04); II 2.09 (1.57-2.86): III 2.46 (1.58-3.22); P < 0.05. Changes in bone metabolism cannot be identified by the determination of a single marker. However, the improved biochemical diagnostic measurement using the b-quotient may provide early information about the progression of a metabolic disorder within the interval of imaging.

Vitamin K nutrition and osteoporosis

Although the abundance of vitamin K-dependent proteins in bone suggests an important function, the precise role of vitamin K in skeletal health remains to be determined. Serum concentrations of vitamin K are reportedly reduced in older individuals and persons with osteoporotic fracture. Whether this is causally related to vitamin K insufficiency or simply reflects inadequate nutritional status is unclear. Circulating levels of undercarboxylated osteocalcin may be a sensitive marker of vitamin K inadequacy and have been reported to be increased in both postmenopausal women and individuals who sustained hip fracture. It is also possible that vitamin K indirectly affects the skeleton via control of renal calcium excretion. The effect of vitamin K antagonists (oral anticoagulants) on both renal calcium excretion and bone density is controversial. Thus, many of the reports implicating a role for vitamin K insufficiency in the development of osteoporosis are conflicting. This review summarizes current knowledge regarding a possible role of vitamin K insufficiency in the pathogenesis of osteoporosis.

Urinary concentration of a specific peptide of type I collagen of bone (CrossLaps): correlation to hydroxyproline

Urinary bone resorption markers, CrossLaps and hydroxyproline are compared in a non-selected group of 93 women. The correlation between CrossLaps and hydroxyproline is satisfactory. The r value is 0.79. Furthermore, it is investigated whether CrossLaps can substitute for hydroxyproline in the estimation of bone loss, using a model based on the combination of several biochemical markers. The results indicate that the two systems reflect related or parallel events, and show that CrossLaps is suitable for use in a normal clinical chemistry laboratory.

Bone alkaline phosphatase and prostate-specific antigen in the monitoring of prostate cancer

A retrospective study has been made on the interrelationship of serum bone alkaline phosphatase (BAP), measured by the Ostase-RIA, and prostate-specific antigen (PSA) in 156 patients with M0 and M1 prostate cancer. BAP is a more sensitive and more specific method of determining osteoblast activity than total alkaline phosphatase (TAP). The main difference between these two assays is seen when the TAP is in the range of normal to twice-normal. BAP shows a low intraindividual variation in M0 disease, and was within normal limits in 18 patients following radical prostatectomy with a PSA < 0.1 ng/ml. A raised BAP was observed in 86.4% of M1 disease at diagnosis before treatment. The change of BAP was concordant with PSA in 69% of 49 cases of M1 disease, although there are marked differences in the rates of change of the two markers. A nadir of PSA < or = 10 ng/ml after androgen blockade in M1 disease was associated with a high probability of a normal BAP.