# Strengthening of CYFRA 21-1 using urine creatinine correction as potential endometriosis biomarker 

## TL;DR

This study shows that adjusting CYFRA 21-1 levels with urine creatinine improves its accuracy as a potential biomarker for endometriosis.

## Contribution

The novel contribution is the use of urine creatinine correction to enhance CYFRA 21-1's performance as an endometriosis biomarker.

## Key findings

- CYFRA/Cr levels were significantly higher in endometriosis patients compared to non-endometriosis patients.
- CYFRA/Cr in the proliferative phase achieved 94.7% sensitivity and 94.4% specificity for endometriosis detection.
- Urine creatinine correction outperformed uncorrected CYFRA 21-1 in diagnostic accuracy.

## Abstract

This study aimed to determine the accuracy of CYFRA 21-1 using urine creatinine correction (CYFRA/Cr) as a biomarker of endometriosis.

This study includes 73 patients from the Indonesian population, with 38 endometriosis and 35 non-endometriosis patients based on laparoscopy. Urine detection of CYFRA 21-1 was done by ELISA method and corrected by urine creatinine constant factor (CYFRA/Cr). Urine creatinine us detected using the ECLIA method.

The CYFRA/Cr ratio was identified in the proliferative and secretory phases. CYFRA 21-1 and CYFRA/Cr levels were significantly higher in endometriosis and were higher in the proliferative phase compared to the secretory phase. The best accuracy was obtained in CYFRA which was corrected with urine creatinine in the proliferative phase with a sensitivity value, specificity, and cutoff value of 94.7%, 94.4%, and of 3,547.99 ng/gr, respectively, compared to CYFRA 21-1 urine levels without correction of creatinine.

The CYFRA to creatinine urine ratio detected in the proliferative phase showed the optimum sensitivity and specificity compared to CYFRA 21-1 spot urine. It has the potential to be a biomarker of endometriosis.