Unique Features

  • Derived exclusively from bone-resorbing osteoclasts
  • Low diurnal variation
  • No dietary influences
  • No accumulation into the circulation in renal or hepatic failure
  • Only bone resorption marker useful in renal research and for non-fasting samples
  • A complete assay panel supporting bone research

RatTRAP (TRAcP 5b) ELISA assay is a solid-phase enzyme activity assay for the determination of osteoclast-derived-tartrate-resistant acid phosphatase isoform 5b (TRACP 5b) in rat serum samples1, 2, 3. It can be used with rat osteoclast culture media.

High amounts of tartrate-resistant acid phosphatase (TRACP) are expressed by bone-resorbing osteoclasts and
activated macrophages. Two forms of TRACP circulate in blood, known as TRACP 5a and TRACP 5b.

TRACP 5b is derived from osteoclasts and TRACP 5a from inflammatory macrophages. Osteoclasts secrete TRACP 5b into the blood circulation as an active enzyme that is inactivated and degraded to fragments before it is removed from the circulation. Thus, TRACP 5b activity does not accumulate into the circulation in renal or hepatic failure. Diurnal variability of serum TRACP 5b is low and the levels are not affected by feeding, allowing sample collection at any time of day.

Recent studies have shown that secreted TRACP 5b indicates the number of osteoclasts rather than their activity.

Gasser JA et al., Effect of chronic metabolic acidosis on bone density and bone architecture in vivo in rats.

Zhao Y et al., Effects of hindlimb unloading and bisphosphonates on the serum proteome of rats.

Rissanen JP et al., Secreted tartrate-resistant acid phosphatase 5b is a Marker of osteoclast number in human osteoclast cultures and the rat ovariectomy model. Calcif Tissue Int. 2008 Feb;82(2):108-1.