Tartrate-resistant acid phosphate as biomarker of bone turnover over the lifespan and different physiologic stages in sheep

Abstract

Background: Currently, the best resources for assessment of bone tissue using imaging techniques are expensive and available in few medical facilities, thus serum or urinary bone turnover biomarkers could be useful as early indicators of prognosis. However, there is a wide range of variability in bone turnover markers due to several factors, such as different ages and metabolic stages, thus it is important to have as much data published on the subject as possible. The aim of this study was therefore to generate a reference range for alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) and validate the already published data.

Results: Serum alkaline phosphatase decreased with age, with statistical difference between the 1 month old and the other groups and between the over 8 years and the 6 months old groups. There was also a statistical difference in the ALP levels between the 3 to 5 years old gestation and lactation groups. For serum tartrate-resistant acid phosphatase, there was a statistical difference mainly between the 1 month old and the 6 months old, 6-8 years old, and above 8 years old groups.

Conclusions: The results obtained could represent a useful tool for future studies using sheep as an animal model for orthopedic research. The different groups presented a wide variation of serum ALP and TRAP levels, however, these variations are entirely explained by known physiology. Therefore, this detailed study confirms the prediction that unexplained changes in these bone turnover markers do not occur during the lifespan of sheep.

Keywords: ALP; Bone tissue; Serum minerals; Sheep; Tartrate-resistant acid phosphatase.

Fig. 1

Box plot presentations of serum concentrations of biomarkers of bone metabolism by age. a Serum ALP activity presented significant difference between 1 month vs. 6 months (P < 0.01), between 1 month vs. 1 year, 2 years, 3–5 years, 6–8 years and >8 years (P < 0.001), between 6 months vs. >8 years (P < 0.05). b Serum TRAP activity presented significant difference between 1 month vs. 6 months, >8 years (P < 0.01), between 1 month vs. 6–8 years (P < 0.001), between 1 year vs. 6 months, >8 years (P < 0.05), between 1 year vs. 6–8 years (P < 0.01), between 2 years vs. 6–8 years (P < 0.05). c Serum calcium activity presented significant difference between 1 month vs. 6 months, 6–8 years (P < 0.05), between 1 month vs. 2 years and 3–5 years (P < 0.01), between 1 month vs. >8 years (P < 0.001), between >8 years vs. 2 years and 3–5 years (P < 0.05), between >8 years vs. 6 month and 6–8 years (P < 0.01) and between >8 years vs. 1 year (P < 0.001). d Serum ALP activity presented significant difference between 1 month vs. 6 months (P < 0.05), between 1 month vs. 1 year (P < 0.01), between 1 month vs. 2 years, 3–5 years, 6–8 years and >8 years (P < 0.001), between 6 months vs. 2 years, 3–5 years, 6–8 years and >8 years (P < 0.05) and between 1 year vs. 3–5 year (P < 0.05). e Serum Magnesium activity presented significant difference between 1 month vs. 3–5 years (P < 0.05) and between 1 month vs. 1 year, 2 years, 6–8 years and >8 years (P < 0.01). Outliers are identified with small circle for out values and star for extreme values

Fig. 2

Box plot presentations of serum concentrations of biomarkers of bone metabolism by physiologic stages. a Serum ALP activity presented significant difference between gestation vs. lactation (P < 0.05). b Serum TRAP activity, there was no significant difference between the groups. c Serum Calcium activity, there was no significant difference between the groups. d Serum Phosphorus activity, there was no significant difference between the groups. e Serum Magnesium activity, there was no significant difference between the groups. Outliers are identified with small circle for out values and star for extreme values