The CatSper-Test




Innovative sperm-function diagnostics for infertile couples

CatSper - the sperm's key to the egg

 To fertilize the egg, sperm must break through its protective coat. This requires CatSper, a large protein complex in the sperm flagellum.

It is well known that loss of CatSper function is associated with male infertility (see scientific background). When CatSper is defective, sperm fail to penetrate the egg coat and fertilization fails.

In the case of CatSper-related infertility, medically-assisted reproduction via IUI (insemination) and IVF is doomed to fail. Affected couples require ICSI to conceive a child.

However, CatSper-related infertility is undetectable by standard semen analysis. As the video shows, affected men are normozoospermic - semen analysis is completely unremarkable.


Current studies suggest that about one in one hundred infertile men with unremarkable semen analysis suffer from a loss of CatSper function. The causes are genetic defects in one of the fifteen CatSper subunits. The CATSPER2 gene is most commonly affected; cases with CATSPER1-, CATSPER3-, or CATSPERE-gene defects have also been described.

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The failure of semen analysis to detect a CatSper-related infertility leads to severe consequences: the couple is often not recognized as infertile. Alternatively, the diagnosis of "unexplained infertility" is given and attempts of medically-assisted reproduction by IUI or IVF are made, which, however, are doomed to fail.


At the Centre for Reproductive Medicine and Andrology of the University Hospital Münster in Germany, the diagnostic gap with regard to CatSper-related infertility has finally been bridged. Here, the CatSper-Test for the early detection of CatSper-related infertility was developed and clinically validated.

The CatSper test makes visible what was once invisible.

With "CatFlux", Truion GmbH offers andrological laboratories CE-certified buffer solutions to perform the innovative CatSper-Test in parallel with a standard semen analysis.

To perform the test, a tiny portion of the raw ejaculate (40 µl) is diluted with the CatFlux Buffers developed by us. After sixty minutes of incubation, the percentage of motile sperm is analyzed under the microscope. Sperm with intact CatSper function are immotile in the CatFlux Test Buffer. On the other hand, sperm continuing to swim in the CatFlux Test Buffer is a strong indication of a loss of CatSper function.

Performing the CatSper-Test using CatFlux enables early detection of CatSper-related infertility and evidence-based selection of fertility treatment.

The CatSper-Test using
CatFlux Buffers *

A patient's semen sample (required volume: approx. 40 microliters) is added to the two CatFlux Buffer solutions.

During incubation (60 minutes, 37 °C), CatSper function is translated 
into a sperm motility response. 

This motility response is quantified with the help of a 
standard light microscope.

The evaluation is very simple: If CatSper function is intact, sperm become immotile in the CatFlux Test Buffer. In contrast, motile sperm in the Test Buffer is indicative of CatSper-related infertility.

Learn more about CatSper, the CatSper-test, and our product, the CatFlux buffers

Request a quote to implement the CatSper-test with CatFlux into your institution's fertility workup **

Learn more about Truion GmbH and
the team behind CatFlux

Winners of the 
Science4Life Venture Cup 2022

Research award of the Bundesverband
reproduktionsmedizinischer Zentren e.V.

Our research in 
DER SPIEGEL

Winner of the Innovation Prize Münsterland in the category "Start-up"

Legal notes
* This is only an overview of the workflow. Please refer to the Instructions for Use provided with the product.
** CatFlux buffers are intended to be used exclusively by trained medical professionals. Delivery to private individuals is not possible.