Chronic gynecologic disorders such as adenomyosis and endometriosis are estrogen-dependent conditions that frequently cause pelvic pain, dysmenorrhea, irregular periods, and infertility, and have a huge impact on women's reproductive health and quality of life.[1] The difference between adenomyosis and endometriosis is that the endometrial glands and stroma are located in the myometrium in the case of adenomyosis, and in the pelvic peritoneum, the ovary, and other structures of the pelvis in the case of endometriosis.[2] While they have individual anatomical features, there are also a number of pathogenic mechanisms shared between both conditions, such as chronic inflammation, hormonal dysregulation, immune response changes, and tissue remodeling.[3] In 2025, a systematic review and meta-analysis of 198,925,726 women across 127 studies found the prevalence of adenomyosis in the general population to be around 1% and endometriosis around 5%.[4] In women with gynecological symptoms, adenomyosis and endometriosis were found in 41%-49% and 18%-42%, respectively, of cases, demonstrating their substantial clinical burden.[4]

Although both conditions have similar symptoms, the distinction between adenomyosis and endometriosis can be difficult, especially in patients with chronic pelvic pain and menstrual abnormalities.[5] Transvaginal ultrasonography is an important non-invasive imaging modality that can be used to identify characteristics of both conditions, but may not be as accurate in some disease subtypes and extensions and in less experienced hands.[6] Secondly, delayed diagnosis continues to be a major problem, and women often suffer from prolonged symptoms before being managed properly.[7]

Cancer antigen 125 (CA-125) is a glycoprotein highly studied as a marker in gynecological diseases whose tissues are derived from the coelomic epithelium.[8] Levels in the bloodstream may rise when there is irritation, inflammation, and involvement of the endometrium in the peritoneum.[9] Increased CA-125 levels have been correlated with adenomyosis-associated dysmenorrhea and the amount of disease burden.[10] Tang et al. (2023) showed that the serum level of CA-125 was significantly elevated in women with adenomyosis and dysmenorrhea, and that the volume of the adenomyotic lesions was positively correlated with serum CA-125 levels.[11] Likewise, a prospective, multicenter study of 919 women found CA-125 to be one of the most useful blood markers when compared to controls with endometriosis and an area under the receiver operating characteristic curve (AUC) of 0.645.[12]

Also, biochemical parameters of interest, such as C-reactive protein (CRP) and ferritin, are measured, given that they are associated with inflammatory and systemic responses.[13] CRP is an acute phase protein, produced by the liver in response to inflammatory cytokines (such as interleukin-6) and may be a marker for the systemic inflammatory component of endometriosis and adenomyosis.[14] Ferritin is a protein that is principally known as a marker of body iron stores and is also an acute phase reactant, which may elevate in case of an inflammatory condition.[13] In women with adenomyosis and endometriosis, whose menstrual periods are often heavy, the alteration in iron metabolism is of special significance.[15]

Evidence of the comparative behaviour of CA-125, CRP and ferritin levels in ultrasound-diagnosed adenomyosis versus endometriosis is limited and has not been investigated in either condition. Furthermore, prior biomarker studies have shown that none of the circulating markers is sufficiently sensitive to distinguish these conditions. Thus, the assessment of these three parameters, which are readily available, may give valuable information regarding the differences in their inflammatory and biochemical profile. The present study was designed to compare the serum levels of the inflammatory markers CA-125, C-reactive protein and ferritin between women with ultrasound diagnosis of adenomyosis and endometriosis to assess whether these markers showed significant differences between the two conditions and investigate the possible use of these markers as biochemical adjuncts to help differentiate these frequently overlapping gynecological disorders.

This was a comparative analytical cross-sectional study conducted at the Department of Obstetrics and Gynaecology, Govt. Lady Wallington Hospital, Lahore, Pakistan, with a biochemical analysis laboratory in the institution. The study was carried out for six months, starting on 1st November 2025 and ending on 30th April 2026.

A sample size was determined for comparing two independent groups with OpenEpi, Version 3.01. Previous studies did not consistently report on the mean and/or standard deviation of all three biomarkers in women with ultrasound-confirmed adenomyosis and endometriosis; thus, a standardized effect size of 0.60 was assumed for the primary comparison. Using a two-sided significance level of 5%, 80% statistical power, and an equal allocation ratio of 1:1, the calculated sample size was approximately 90 participants, comprising 45 women in each group. After accounting for a 10% potential non-response or incomplete-data rate, the final sample size was increased to 100 women, with 50 participants in each group.

A non-probability consecutive sampling technique was used to recruit eligible participants. The study included women aged 18-45 years, who presented in the outpatient department with ultrasound-proven adenomyosis or endometriosis. Participants who had a confirmed diagnosis based on the characteristic findings of transvaginal or transabdominal ultrasonography and had given informed written consent were eligible to be enrolled. Women who had concurrent adenomyosis and endometriosis, pregnancy, known gynecologic malignancy, acute infectious and inflammatory disorder, chronic inflammatory and autoimmune disorder, chronic liver or renal disorder, and known hematologic disorder were excluded. Women who had received transfusion of blood, iron, or hormone therapy within three months were also excluded, as they might also have affected the biochemical parameters measured.

Eligible women were recruited from the OPD after written informed consent was obtained following approval from the institutional ethical review committee. A structured data collection proforma was used to collect demographic and clinical data such as age, body mass index (BMI), parity, menstrual history, duration of symptoms, dysmenorrhea, pelvic pain, and abnormal uterine bleeding data. Medical and gynecological histories were also recorded, if applicable. Diagnosis was confirmed with ultrasound examinations, and participants were placed in the different study groups. Adenomyosis was identified by characteristic ultrasonographic features, including myometrial cysts, myometrial asymmetry, fan-shaped shadowing, subendometrial lines and buds, and an irregular or interrupted junctional zone. Lesions consistent with endometriosis were seen, including ovarian endometriomas, ground-glass echogenicity, and lesions suggestive of deep endometriosis.

Venous blood (about 5 mL) was drawn in aseptic conditions from each participant. Blood samples were sent to the institutional lab for biochemical analysis, following standard laboratory procedures. CA-125 levels were measured by enzyme-linked immunosorbent assay (ELISA) or an appropriately validated automated immunoassay method, and CRP concentrations were measured by immunoturbidimetric assay. Serum ferritin concentrations were measured using a chemiluminescent immunoassay or another validated immunoassay method. The same laboratory protocols and equipment were used for both groups, in order to reduce measurement variability across the three parameters.

The values obtained were graphed in standardized units (U/mL for CA-125; mg/L for CRP; and ng/mL for ferritin). To minimize measurement bias, wherever possible, the participants were masked for the laboratory personnel in order to prevent knowledge of the diagnostic group from influencing the results. All collected information and laboratory results were entered into a structured database for subsequent statistical analysis.

IBM SPSS Statistics, version 26 was used to analyze the collected data. The Shapiro–Wilk test was used to test whether quantitative variables such as age, BMI, CA-125, CRP, and ferritin levels were normally distributed. All the variables were quantified as mean ± standard deviation for normally distributed variables, and as median and interquartile range for non-normally distributed variables. Data for categorical variables such as parity, dysmenorrhea, and abnormal uterine bleeding were reported as frequencies and percentages. Demographic and clinical variables measured were compared between the two groups with an independent-samples t-test and Mann–Whitney U test for continuous variables, and chi-square test or fisher's exact test for categorical variables.

The independent-samples t-test or the Mann–Whitney U test was used to compare the levels of serum CA-125, CRP, and ferritin between women with adenomyosis and endometriosis according to the distribution of the data. Receiver operating characteristic (ROC) curve analysis was carried out to evaluate the power of each biomarker to differentiate adenomyosis from endometriosis. For each parameter, the area under the curve (AUC) and its 95% confidence interval were computed. Optimal cut-off points were explored, and the sensitivity and specificity were calculated. Multivariable logistic regression analysis was performed to assess the independent association of the biomarkers with the diagnostic group after adjusting for potential confounding variables, including age and BMI. A p-value of less than 0.05 was considered statistically significant.

The study included 100 women, 50 of whom had ultrasound-proven adenomyosis and 50 had endometriosis. Women with adenomyosis were significantly older than women with endometriosis and had a higher BMI. The differences in parity were also quite large between the groups, while the length of symptoms was similar. The endometriosis group also had more women in their younger age groups, while the adenomyosis group had more women in their older age groups (Table 1).

As far as clinical presentation is concerned, dysmenorrhea was common in both groups, and there was no statistical difference. Chronic pelvic pain, however, and infertility and dyspareunia were significantly more common in women with endometriosis. However, women with adenomyosis were significantly more likely to report abnormal uterine bleeding and heavy menstrual bleeding than women without (Table 2).

The serum CA-125, CRP, and ferritin levels were significantly higher in women with endometriosis when compared to women with adenomyosis. The results showed that the biochemical profiles of the two diagnostic groups were different (Table 3).

The characteristic disease-specific findings of the disease are demonstrated by ultrasonographic evaluation in both groups. Among the women with adenomyosis, myometrial symmetry, myometrial cysts, fan-shaped shadowing, and regular or uninterrupted junctional zones were often observed. Ovarian endometriomas and ground-glass echogenicity were most common in women with endometriosis, but features suggestive of deep endometriosis were also present (Table 4).

ROC curve analysis demonstrated that CA-125 had the highest discriminatory performance among the three evaluated biomarkers, followed by ferritin and CRP. However, none of the three biomarkers was able to provide good diagnostic discrimination, indicating that they were not able to make a firm diagnosis between adenomyosis and endometriosis alone (Table 5).

Multivariable logistic regression analysis demonstrated that age, CA-125, and ferritin were independently associated with endometriosis compared with adenomyosis. BMI and CRP did not demonstrate statistically significant independent associations after adjustment for the other variables included in the model (Table 6).

Table 1. Comparison of demographic and baseline characteristics between women with adenomyosis and endometriosis (n=100)

Table 2. Comparison of clinical characteristics and presenting symptoms between the study groups (n=100)

 Table 3. Comparison of serum CA-125, CRP, and ferritin concentrations between women with adenomyosis

and endometriosis (n=100)

Table 4. Distribution of ultrasound findings among women with adenomyosis and endometriosis

Table 5. Diagnostic performance of serum CA-125, CRP, and ferritin for differentiating endometriosis from adenomyosis

Table 6. Multivariable logistic regression analysis of factors associated with endometriosis (versus adenomyosis)

The present study comparatively evaluated serum CA-125, C-reactive protein (CRP), and ferritin concentrations among women with ultrasound-confirmed adenomyosis and endometriosis. The results showed much greater levels of each of the three biomarkers in the women with endometriosis than in the women with adenomyosis. CA-125 showed the highest discriminatory value, followed by ferritin and CRP, but none of these three parameters was highly accurate. The results indicate that the circulating biochemical profiles are different between the two conditions, but with the relatively small number of patients and overlapping inflammatory mechanisms of both disorders, the differences observed must be viewed with caution.

Women with adenomyosis in the present study had significantly higher BMI, parity, and age than women with endometriosis. These results were similar to the clinical and reproductive features that have been observed in both conditions. This is also consistent with the predominance of younger women in the endometriosis group, which is commonly studied in endometriosis research.

In a multicentre prospective cohort study of 919 women, Burghaus et al. (2024) assessed the performance of blood-based biomarkers in suspected endometriosis and adenomyosis and showed that the performance of the biomarkers depends on the underlying disease category and clinical characteristics. Similarly, Tang et al. (2023) reported an inverse association between age and serum CA-125 concentrations among women with adenomyosis. A different age distribution has been found between the two groups in the present study and thus might have affected the concentration of the biomarkers measured and should be taken into account when comparing between groups.[12, 16]

Regarding clinical presentation, dysmenorrhea was frequent in both groups, without a statistically significant difference. Women with endometriosis, however, were much more likely to report chronic pelvic pain, infertility or dyspareunia, while women with adenomyosis were more likely to report abnormal uterine bleeding or heavy menstrual bleeding. The results of these studies were due to the different clinical presentations of the two disorders.

A case-control study, published in 2025 by Sarikaya Kurt et al., investigated clinical and laboratory parameters of women with endometriosis and found differences between the affected women and controls in reproductive and clinical parameters.[17] Peker et al. (2026), in a retrospective cohort of 162 women with adenomyosis, also investigated haemoglobin parameters and showed that levonorgestrel-releasing intrauterine systems are associated with improvement in haemoglobin levels. They pointed out the clinical significance of the menstrual blood loss and hematological changes in adenomyosis.[18] The higher frequency of abnormal and heavy menstrual bleeding in our adenomyosis group was consistent with this clinical association.

The high serum CA-125 levels among women with endometriosis than in women with adenomyosis was one of the important findings in the present study. High levels of CA-125 have been studied in detail as a circulating marker in endometriosis and is linked to irritation and activity of the peritoneum. In a multi-center study, the investigators Burghaus et al. (2024) found that CA-125 had the highest AUC (0.645; 95% CI 0.600-0.690) when compared to all other individual biomarkers and the endometriosis group versus the controls. They also recorded a correlation between higher CA-125 levels and a higher stage of endometriosis.[12]

 In another study, Tang et al. (2023) reported that women with adenomyosis who developed dysmenorrhea had significantly higher CA-125 levels, and that serum CA-125 levels were positively correlated with the volume of adenomyotic lesions.[16] The results confirm the clinical importance of CA-125 in both conditions, but its levels may change depending on the type and severity of disease and presentation. The increased levels of our endometriosis group therefore suggest that there may be a difference between the two diagnostic groups, but are not sufficient to define CA-125 as a marker for endometriosis.

Another finding of the present study was that women with endometriosis had significantly higher CRP levels. The significance of this discovery could be associated with the inflammatory mechanisms of cells expressing ectopic endometrium and the local and general immune response reactions that occur with the disease. Similarly, in a cross-sectional study of 120 women (80 with endometriosis and 40 healthy), Hameed et al. (2023) found significantly elevated hs-CRP levels in the endometriosis group.[19]

In the present study, ferritin levels were also significantly elevated in women with endometriosis. Ferritin is mainly used to measure iron stores but it is also an acute phase reactant, and can be affected by the activity of inflammation. In a cross-sectional analysis of 6,551 participants from the NHANES, Xu et al., (2023) found a positive relationship between increasing serum ferritin levels and endometriosis. Women in the highest quartile of ferritin were more likely to have endometriosis than women in the lowest quartile (OR: 2.11; 95% CI: 1.31-3.40; p=0.004).[20] However, Kasoha et al. (2025) did not find a significant difference in serum ferritin levels between women with endometriosis and controls.[21]

 In the study by Izumi et al. (2023), higher levels of hepcidin were observed in menstrual blood of women with endometriosis, and the researchers provided experimental data supporting a correlation between iron accumulation in the menstrual blood and production of inflammatory cytokines and oxidative stress.[22] These findings support the hypothesis for a possible biological mechanism linking iron metabolism and endometriosis; however, the variables mentioned, such as menstrual blood iron, hepcidin, and circulating serum ferritin, are different biological parameters. Therefore, the higher levels of ferritin in our endometriosis group must be taken with a pinch of salt, especially as iron supplementation, menstrual blood loss, and systemic inflammation can also affect ferritin levels.

The present study also has several limitations. First, the sample size is relatively small, and the study was conducted in a single center, which may restrict the generalizability of the results. Second, the diagnosis using ultrasound may depend on the operator's skills and on different interpretations of the images.

Thirdly, the cross-sectional design did not enable the evaluation of the changes in biomarker levels over time, nor did it enable causal conclusions to be drawn. In addition, the levels of ferritin can be influenced by iron status, menstrual blood loss, and inflammatory conditions, and CA-125 can be influenced by the extent of the disease and menstrual characteristics. Lastly, excluding women who had concurrent adenomyosis and endometriosis decreased diagnostic overlap, but made the results less generalizable to women with multiple disease states. More multicentre studies with larger sample sizes, more consistent ultrasound criteria, and the inclusion of iron parameters and inflammatory parameters are warranted.

The overall results indicated that serum levels of CA-125, CRP, and ferritin were significantly distinct between women with ultrasound diagnosis of adenomyosis and endometriosis, with the concentration of CA-125 showing the best, though limited, discriminatory ability. The use of these markers for the two disorders as separate diagnostic markers cannot be recommended based on these findings only. They may be helpful in understanding the differential biochemical profile of the two disorders. They could serve as additional parameters in larger prospective studies to be validated.

Patients treated with rifaximin-based therapy had a lower prevalence of sarcopenia and cognitive dysfunction compared to those treated with lactulose-based therapy. However, after adjustment for potential confounding factors, only the association with cognitive dysfunction remained statistically significant. These results indicate that treatment with rifaximin may be associated with improved cognitive function in RE patients Serum CA-125, CRP, and ferritin concentrations were significantly higher in women with ultrasound-confirmed endometriosis compared with those with adenomyosis. The best discriminatory biomarker was CA-125, followed by ferritin and CRP, but all were only modestly accurate in terms of diagnostic performance. The results indicate that the three markers may be complementary in their biochemical characteristics of both diseases, but are not independent diagnostic markers. A larger number of patients should be studied to confirm their usefulness as additional biochemical markers for distinguishing adenomyosis from endometriosis.

Matalliotakis, M., et al., Coexistence of gynecological pathology with endometriosis and adenomyosis. Molecular and clinical oncology, 2025. 24(2): p. 12.

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