Endometriosis is an inflammatory disease, so a lot of people have questions about blood tests that look at inflammation. Remember, all these tests might be an indication of endometriosis, but they are very nonspecific. The only way to definitively diagnose endometriosis is through surgery.
What is C-Reactive Protein (CRP)?
- Sproston, N. R., & Ashworth, J. J. (2018). Role of C-reactive protein at sites of inflammation and infection. Frontiers in immunology, 9, 754. Retrieved from https://www.frontiersin.org/articles/10.3389/fimmu.2018.00754/full
“C-reactive protein (CRP) is an acute inflammatory protein that increases up to 1,000-fold at sites of infection or inflammation….Having been traditionally utilized as a marker of infection and cardiovascular events, there is now growing evidence that CRP plays important roles in inflammatory processes and host responses to infection including the complement pathway, apoptosis, phagocytosis, nitric oxide (NO) release, and the production of cytokines, particularly interleukin-6 and tumor necrosis factor-α….There are many factors that can alter baseline CRP levels including age, gender, smoking status, weight, lipid levels, and blood pressure (13). The average levels of CRP in serum in a healthy Caucasian is around 0.8 mg/L, but this baseline can vary greatly in individuals due to other factors, including polymorphisms in the CRP gene (14)…. C-reactive protein levels are known to increase dramatically in response to injury, infection, and inflammation (Figure 1). CRP is mainly classed as an acute marker of inflammation, but research is starting to indicate important roles that CRP plays in inflammation.”
So what does this have to do with endometriosis?
Endometriosis is an inflammatory disease, so one might expect the markers to be high. But this does not necessarily show in blood tests:
- Kianpour, M., Nematbakhsh, M., & Ahmadi, S. M. (2012). C-reactive protein of serum and peritoneal fluid in endometriosis. Iranian journal of nursing and midwifery research, 17(2 Suppl1), S115. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3696960/
“Findings: There was no significant difference between the CRP serum level in patients with endometriosis and infertile women without endometriosis. There was a significant difference in peritoneal level of CRP between case and control groups (p < 0.05). Conclusions: The findings suggested that measurement of this marker in patients’ serum or plasma cannot be used to diagnose endometriosis. It is further recommended that a combination of different markers might be helpful in this regard that could be studied in future.”
So we may not see an increase in the blood test, but there is a difference in the peritoneal (from the abdomen/pelvis) samples:
- Kianpour, M., Nematbakhsh, M., & Ahmadi, S. M. (2012). C-reactive protein of serum and peritoneal fluid in endometriosis. Iranian journal of nursing and midwifery research, 17(2 Suppl1), S115. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3696960/
“Compared to the control group, the CRP level of the peritoneal fluid were higher in patients with endometriosis (p<0.05). Pelvic endometriosis is a chronic inflammatory disease that is in association with a general inflammatory response in the peritoneal cavity.[34,35] This disease is known to have an immunological background.[36] Macrophage constitutes 82- 99% of the all the cell population of peritoneal fluid.[37–39] Literature has repeatedly reported an increase of total peritoneal fluid cell numbers, cell concentration and macrophages in endometriosis patients in compare to the control.[40–43] The study of Dunselman et al. also confirmed that there is an increase in the number and concentration of peritoneal cells in patients with endometriosis as compared to the control group.[38]”
What is CA-125?
It’s a test that looks at markers for certain cancers, but if your doctor orders it and it’s high, don’t let it scare you. “…many noncancerous conditions can increase the CA 125 level. Many different conditions can cause an increase in CA 125, including normal conditions, such as menstruation, and noncancerous conditions, such as uterine fibroids” (Mayo Clinic, n.d.).
Reference
Mayo Clinic. (n.d.). CA-125 test. Retrieved from http://www.mayoclinic.org/tests-procedures/ca-125-test/basics/definition/prc-20009524
It can also be high in people with endometriosis:
- May, K. E., Conduit-Hulbert, S. A., Villar, J., Kirtley, S., Kennedy, S. H., & Becker, C. M. (2010). Peripheral biomarkers of endometriosis: a systematic review. Human reproduction update, 16(6), 651-674. Retrieved from http://humupd.oxfordjournals.org/content/16/6/651.full
“Studies published since continue to demonstrate a correlation between raised CA125 levels and endometriosis (Abrao et al., 1999; Somigliana et al., 2004; Agic et al., 2008; Seeber et al., 2008), and some imply a correlation with stage of disease (Chen et al., 1998; Amaral et al., 2006; Martinez et al., 2007; Rosa e Silva et al., 2007). One study has indicated that CA125 may be more accurate at diagnosing women with later stages of disease (Maiorana et al., 2007).”
For more on peripheral biomarkers of endometriosis see:
May, K. E., Conduit-Hulbert, S. A., Villar, J., Kirtley, S., Kennedy, S. H., & Becker, C. M. (2010). Peripheral biomarkers of endometriosis: a systematic review. Human reproduction update, 16(6), 651-674. Retrieved from http://humupd.oxfordjournals.org/content/16/6/651.full