Bone metabolism

Product name

TRAP5b, Human (Quidel®)

Tartrate-resistant acid phosphatase

Enzyme activity is measured

Range2.5 – 15.5 U/L
Sensitivity0.2 U/L
Incubation time2 hours
Sample volume50 µl
Sample type

Serum, Heparin-plasma, cell culture

Sample preparation

Whole blood and Serum can be stored 8 hours at room temperature, Serum and Plasma for 2 days at 2-8 °C, 1 month at -20 °C or for longer storage at -80 °C. Maximum 3 freeze- and thaw cycles.

Reference values
  • Premenopausal women  30-44 years (N=31)  4.0 +/- 1.4 U/l
  • Postmenopausal women > 50 Jahre (N=36)  4.3 +/- 1.5 U/l
  • Men                                      > 20 Jahre   (N=91)   4.0 +/- 1.4 U/l

Reference values from children are available.


Human, (Rhesus macaque)

Tests96 Tests
Intended use

TRAP5b is highly specific for osteoclasts in-vivo, although it has been shown to be secreted by alveolar macrophages under certain conditions. As a bone marker, TRAP5b is unique in that it reflects the number of osteoclasts and, as changes in bone resorption are usually associated with changes in osteoclast number, TRAP5b is a useful indicator of bone resorption.

TRAP5b is not linked specifically to osteoclast mediated collagen degradation, rather it is secreted by active osteoclasts whether or not they are metabolizing bone substrate. In certain disease states where bone resorption and the number of active osteoclasts is uncoupled, this may be very significant. TRAP5b data may also be seen as supportive of other resorption data indicating an increase in the number of active osteoclasts.

In general, in-vivo TRAP5b data correlate highly with other markers of bone resorption including DPD, NTX and CTX. As a serological bone resorption marker there is substantial synergy with bone formation markers, particularly BAP. It may therefore be beneficial to look at both BAP and TRAP5b using the same sample type, Serum.

TRAP 5b is considered as the most important marker of bone resorption rate in renal failure patients. Bone metabolism markers like CTX, NTX, BAP and osteocalcin accumulate in blood because the markers are not cleared by the dysfunctional kidney. This can lead to elevated marker levels in renal osteodystrophy, a bone disease affecting the majority of renal failure patients, causing misinterpretation of bone marker results.

TRAP5b is inactivated rapidly during circulation and degraded into fragments, before clearance from blood circulation through the liver. Therefore renal dysfunction does not affect enzymatically active intact TRAP5b levels. Even in liver failure, inactive fragments accumulate in blood, while enzymatically active intact TRAP5b molecules do not accumulate.

Serum TRAP5b demonstrates little variation over the day. This represents a great advantage over serum and urinary markers which demonstrate variations of up to 137 % over the day. TRAP5b also demonstrates minimal response to fasting, whereas other markers decrease up to 18 % during fasting. Due to its low biological noise, the signal-to-noise ratio of TRAP5b in disease and therapy situations may in fact be larger than for other serum and urinary telopeptides markers.

Changes of the TRAP activity during a therapy monitoring allow the judgment of the efficiency of anti-resorptive therapies.
Furthermore, increased TRAP5b values in serum and plasma were found in diseases with enhanced bone resorption:

  • Paget’s disease
  • Hemodialysis
  • Follow up after kidney transplantation
  • Hyperthyreosis

Method Description:

The Quidel® TRAP5b Assay is a 2-step direct capture Enzym-Imunoassay.
Naturally occurring, inactive TRAP5b fragments in the serum may interfere with the detection of TRAP5b in physiological samples. The Quidel® TRAP5b Assay avoids the influence of the inactive fragments by using two different monoclonal antibodies. The assay employs two unique monoclonal antibodies, Trk49 and Trk62, generated with immunization of purified TRAP5b from human bone cells. The first antibody, Trk49, is highly specific to inactive TRAP5b fragments; the second antibody, Trk62, is highly specific for intact, active TRAP5b. Trk49 binds inactive TRAP5b fragments, thereby making Trk62 more available to bind active TRAP5b in the microwell. The resulting TRAP5b assay is very specific with high precision and a wide range of linearity.


Product informations

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