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

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.