Tampons could track MS nerve damage, study suggests

Menstrual fluid collected from tampons could one day provide a simple, non-invasive way to measure a biomarker of nerve damage and potentially track disease activity in neurological conditions such as multiple sclerosis (MS), new research suggests.

Because neurofilament light chain, or NfL, has emerged as a promising biomarker of MS, detecting it in menstrual fluid raises the possibility of monitoring disease activity through the natural monthly cycle of menstruation.

Researchers at Nextgen Jane, in collaboration with Siemens Healthineers, found that NfL, a protein released when nerve cells are damaged, can be reliably detected in tampon-collected menstrual samples.

“Finding that NfL tracks with estrogen levels in menstrual fluid, independent of how much blood is in the sample, tells us there is real biology here, not just contamination,” said Ridhi Tariyal, chief executive and co-founder of Nextgen Jane.

“That changes what this specimen means for neurology.”

In MS, the immune system mistakenly attacks healthy parts of the brain and spinal cord, causing inflammation and damage that can lead to symptoms such as fatigue, numbness, muscle weakness, and problems with balance or vision.

Confirming a diagnosis of MS usually requires a combination of physical and neurological examinations, MRI scans to check for brain and spinal cord damage, and lab tests.

These can include detecting certain proteins in cerebrospinal fluid, the fluid that surrounds the brain and spinal cord, which may indicate inflammation in the brain or spinal cord.

After diagnosis, patients are usually monitored through clinical assessments and routine MRI scans, which help doctors detect changes in disease activity and determine whether treatments are working.

However, MRI assessments can be costly and are usually done once or twice a year, which can prevent doctors from spotting early changes and making timely treatment adjustments.

Because of these challenges, researchers have long sought cost-effective, more accessible biomarkers that could help detect MS earlier, monitor disease activity over time, and evaluate treatment response.

One of the most promising candidates is NfL, a protein found in nerve cell fibres that is released into the bloodstream and cerebrospinal fluid when nerve cells are injured.

To explore whether menstrual fluid could serve as a source for detecting this biomarker and, more broadly, as a non-invasive specimen for monitoring neurological, hormonal and inflammatory signals, researchers analysed 99 tampon-collected menstrual fluid samples from 91 participants.

They used Siemens Healthineers’ highly sensitive NfL assay on its automated testing platform. The team also measured hormonal and inflammatory molecules.

NfL was detected in 98 of the 99 menstrual fluid samples analysed, suggesting the biomarker can be reliably measured in tampon-collected samples.

The researchers also found that NfL levels were associated with estradiol levels, a form of the hormone oestrogen, and that this relationship remained significant even after adjusting for differences in blood content between samples.

By comparison, levels of inflammatory markers were more strongly linked to blood content itself.

According to the researchers, this suggests NfL detection was not merely the result of blood contamination, but may reflect biologically meaningful changes that could potentially be tracked over time through routine menstrual sampling.

Building on these findings, Nextgen Jane is now planning prospective studies to investigate whether menstrual NfL and other neurological proteins can be used to track disease activity over time in conditions such as MS.

“The menstrual cycle provides a built-in longitudinal framework: the same individual, the same biological process, month after month,” said Stephen Gire, chief scientific officer at Nextgen Jane.

“Coupling the NextGen Jane platform with Siemens Healthineers’ highly sensitive NfL assay gives us a path to study neurological biomarker trajectories in a way that has not been possibe before.”