C reactive protein (CRP) is used in this study as a method of detecting sub-clinical inflammation. Increased level of CRP increases the probability of endometriosis.
A high sensitivity assay is more accurate than a classical assay for the measurement of plasma CRP levels in endometriosis.
Endometriosis is associated with chronic subclinical inflammation. C-reactive protein (CRP), a marker
of inflammation, could serve as a biomarker of endometriosis. We tested the hypothesis that a high sensitivity CRP
assay (hsCRP) is more accurate than a classical CRP assay in the detection of subclinical inflammation in plasma of
women with endometriosis.
CRP levels were measured by hsCRP and classical CRP assays in plasma of 204 women with
endometriosis and 91 women without endometriosis. Both assays were compared with respect to their value for
the diagnosis of endometriosis.
The number of plasma samples with detectable CRP was significantly higher (100%) using the hsCRP assay
when compared to the classical CRP assay (42.7%) (p < 0.0001). Significantly increased CRP plasma levels were found
in women with endometriosis when compared with controls when the hsCRP assay was used in samples obtained
during the luteal phase (p = 0.008). The highest discriminative ability for the diagnosis of endometriosis was also
obtained using the hsCRP assay during the luteal phase, especially for moderate -severe endometriosis. At a cut-off
level of hsCRP > 0.71 mg/L, moderate-severe stages were diagnosed with 80.7% sensitivity and 63.9% specificity
during the luteal phase. Using a similar cut-off value for CRP analyzed by the classical method, moderate-severe
endometriosis was diagnosed with lower sensitivity (67.7%, p = 0.06) and comparable specificity (63.9%).
The hsCRP assay was superior to the classical CRP assay for the detection of low CRP levels and for
revealing subclinical inflammation in plasma of women with endometriosis.