How Ankylosing Spondylitis Affects Women Differently

While back pain is the characteristic symptom of ankylosing spondylitis that presents in people of any sex, other associated symptoms present differently in women, often leading to delayed and inaccurate diagnoses.

This article will discuss why women are less likely to be diagnosed with ankylosing spondylitis, differences in symptoms in women, and differences in diagnostic markers of the condition in women.

Why Women Are Less Likely to be Diagnosed with Ankylosing Spondylitis

Ankylosing spondylitis is an inflammatory, autoimmune disorder that causes pain and stiffness of the spine. Back pain and stiffness are the most common symptoms associated with ankylosing spondylitis that may be chronic and progressive in nature or may occur in episodes that come and go. There is also often involvement of the sacroiliac joints, between the hip bones and the sacrum; the sacrum sits between the lumbar spine and the coccyx (tailbone).

Because ankylosing spondylitis is three times more likely to be diagnosed in men than in women, a correct diagnosis is often overlooked due to outdated beliefs that ankylosing spondylitis does not commonly occur in women and that symptoms are more mild despite evidence showing that there is no significant difference in symptom severity between men and women.

Women with ankylosing spondylitis are also more likely to be misdiagnosed with another condition, such as rheumatoid arthritis or fibromyalgia, and wait a longer period of time to be correctly diagnosed due to differences in how symptoms of ankylosing spondylitis manifest in women compared with men.

Disease progression may also be slower in women, and research reveals that it takes an average of 6.2 years for women to be accurately diagnosed with ankylosing spondylitis compared to 5.5 years for men.

Ankylosing Spondylitis Symptoms in Women 

While back pain and sacroiliac joint involvement are common in both men and women with ankylosing spondylitis, women present with other symptoms that are less common in men, such as:

• More pain at night
• Increased fatigue 
• Increased stiffness 
• Enthesitis (inflammation of the sites on tendons and ligaments that attach to bones)

While ankylosing spondylitis can affect many other areas of the body in both men and women, women often complain of more symptoms affecting the neck, knees, and hips.

Women also more commonly present with inflammatory, systemic symptoms associated with ankylosing spondylitis, including:

• Psoriasis: A chronic inflammatory skin condition causing scaly, itchy patches
• Uveitis: An inflammatory condition that affects the colored portion of the eye
• Inflammatory bowel disease: An inflammatory condition that affects the gastrointestinal tract, such as Crohn’s disease and ulcerative colitis

Sex Differences in Diagnostic Markers

In addition to different symptoms between men and women with ankylosing spondylitis, there are also diagnostic markers that differ between the two, making it more difficult to diagnose ankylosing spondylitis in women.

Cytokines

Helper T-cells, which are specialized types of lymphocytes, or white blood cells, develop in the thymus gland and play an important role in immunity. Helper T cells release cytokines, specific proteins that activate immune system responses, in the presence of invading pathogens like viruses and bacteria that cause diseases.

Abnormal activation of these cytokines, especially one in particular called Interleukin 17 (IL-17), often underlies many autoimmune disorders where the body initiates an immune response to attack its own healthy cells.

Blood serum levels of IL-17 have been found to be significantly elevated in men with ankylosing spondylitis but not in women, indicating significant differences in disease presentation between the two sexes.

C-Reactive Protein

Compared with men, women with ankylosing spondylitis have lower blood plasma levels of C-reactive protein, a protein that circulates in the blood and increases in response to inflammation in the body.

Genetic Differences

Patients with ankylosing spondylitis present with alterations in over 3,500 genes not seen in those without the condition, but 650 of these genes are expressed differently in men and women. These genetic differences affect the breakdown of cellular components, breakdown of bone, wound healing, blood clotting, and other cellular processes.

Because of these differences, women with ankylosing spondylitis are less responsive to medications used to treat ankylosing spondylitis and more likely to have progressively worsening symptoms. These changes also make it more difficult to accurately use blood work to diagnose ankylosing spondylitis in women.

Summary

If you think you may have ankylosing spondylitis, it is important that you advocate for yourself in order to receive the correct diagnosis. Due to the misconception that women are less likely to have ankylosing spondylitis, medical professionals may overlook your symptoms when considering possible causes of pain and stiffness that women experience.

Make sure to tell your healthcare provider about any unusual symptoms you are experiencing since women often present with different systemic symptoms and pain patterns than men.