Biochemical markers osteocalcin

Kanbur, N. O., Derman, O., and Kinik, E. (2002). Osteocalcin. A biochemical marker of bone turnover during puberty. Int.. Adolesc. Med. Health 14,235-244. 

Glucocorticoids can even cause osteoporosis when they are used for long-term replacement therapy in the Addison s disease, as has been shown by a study of 91 patients who had taken glucocorticoids for a mean of 10.6 years, in whom bone mineral density was reduced by 32% compared with age-matched controls (SEDA-19, 377 198). However, these results contrasted with the results of a Spanish study in patients with Addison s disease, in which no direct relation was found between replacement therapy and either bone density or biochemical markers of bone turnover of calcium metabolism (alkaline phosphatase, osteocalcin, procollagen I type, parathormone, and 1,25-dihydroxycolecalciferol) (SEDA-19, 377 199). 

Treatment with beclomethasone dipropionate 1500 micrograms/day for 6 weeks significantly reduced markers of bone formation (osteocalcin and PICP), whereas fluticasone propionate 750 micrograms/day had no effect. Neither drug affected biochemical markers of bone resorption. There was no significant change in bone density (SEDA-22,183). 

The use of glucocorticoids is associated with reduced bone mineral density, bone loss, osteoporosis, and fractures. This has been described during the long-term use of glucocorticoid by any route of administration (SEDA-19, 377) (SEDA-20, 374). The effects of glucocorticoids on bone have been reviewed (SEDA-21, 417) (165). Biochemical markers of bone mineral density are listed in Table 4. In patients with secondary hypoadrenaUsm, hydrocortisone 30 mg/day for replacement produced a significant fall in osteocalcin, indicating bone loss. Lower doses of hydrocortisone (10 mg and 20 mg) produced similar efficacy in terms of quality of life but smaller effects on osteocalcin concentrations and therefore a reduction in bone loss (166). 

Of current biochemical markers, total ALP or BAP provides the highest clinical sensitivity and specificity in the diagnosis and monitoring of Paget s disease. Although total ALP is most often used, BAP is more sensitive than total ALP in mild Paget s disease. Osteocalcin is relatively insensitive and less useful than BAP in Paget s disease. Total ALP is not useful in metabolic bone diseases with mild elevations of BAP. 

An estimated 75 million people are affected by osteoporosis to some degree in the United States, Europe, and Japan. Osteoporosis is a systematic skeletal disease characterized by bone mass and microarchitectural deterioration with a consequent increase in bone fragility and susceptibility to fracture. Operationally, osteoporosis can be defined as a certain level of bone mineral density. The definition of osteoporosis is somewhat arbitrary and is based on epidemiological data relating fracture incidence to bone mass. Uncertainty also is introduced due to variability in bone densitometry measurements. Other clinical measures to assess the skeleton include collagen cross-links (measure of bone resorption) and levels of bone-specific alkaline phosphatase and osteocalcin (bone formation). A list of biochemical markers of bone remodeling is provided in Table 37-3. Measurement of total serum alkaline phosphatase level and urinary hydroxyproline or calcium levels is of limited value. 

Gundberg CM. Osteocalcin. In Eastell R, Baumann M, Hoyle NR, Wieczorek L., eds. Bone markers biochemical and clinical perspectives. London Martin Dunitz, 2001 65-72. 

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