The release focuses on a study that found elevated levels of the hormone irisin in healthy teenage girls who have been diagnosed with polycystic ovary syndrome (PCOS). While the release stresses that these findings are preliminary, and need to be confirmed through additional research, it suggests that testing irisin levels may be a way of determining whether teenagers have PCOS. This, in turn, would both allow for early treatment of PCOS symptoms in girls who have the condition, and limit misdiagnoses (and related treatment) of PCOS in girls who do not have the syndrome.
But the detection of an association between elevated irisin level and PCOS is the first of the many steps needed to determine whether testing irisin has greater diagnostic accuracy than current tests for the condition. Even more speculative is the notion that a treatment for PCOS could be targeted to altering irisin levels. The release overstates the significance of this small, preliminary study.
According to the U.S. Office on Women’s Health, as many as 1 in 10 women of childbearing age may have PCOS — and the syndrome can occur in girls as young as age 11. And PCOS is associated with a number of complications, incuding an increased risk of type 2 diabetes, high blood pressure, and infertility. In other words, PCOS is something folks should pay attention to. However, many aspects of PCOS remain a mystery. For example, it’s not clear what causes PCOS, and — according to the Mayo Clinic — “there’s no specific test to definitively diagnose polycystic ovary syndrome.”
The release proposes that a hormone target — irisin — may give medical professionals a new technique for identifying PCOS in girls who are still undergoing puberty. Even though it noted that the study is preliminary, the release goes overboard stating that the test could “improve diagnosis” in the headline.
The measurement of irisin and its usefulness as a treatment target have been the subject of controversy, recounted in a 2015 Science article.
“Since it was first described in 2012, the hormone irisin has generated hope and controversy. In mice, the molecule appeared to be released from muscles after exercise and circulate in the blood, promoting the generation of energy-burning brown fat cells. But as other labs tried to expand on the idea that irisin is a key regulator of metabolism and a potential drug target for metabolic disease in humans, they got contradictory results. A new study throws another hitch in the irisin story by calling into question the reliability of antibody-based test kits often used to detect the molecule. Its authors claim that many of the studies measuring irisin in human blood are invalid.”
The release doesn’t address costs at all. Given how far this is removed from widespread clinical applications, that’s somewhat understandable. Then again, if a clinical application is so far away, it’s hard to understand why one would claim in the headline that this test “may reduce teenagers wrongly diagnosed with PCOS.”
The researchers presumably know the general cost of measuring irisin levels in a blood test. Is it relatively inexpensive? Even a modest indication of general cost would have been welcome. The release could have acknowledged that the cost of the test in a research setting might be quite different from the cost of a clinical test.
The benefit here would be identifying levels of irisin found in patients with PCOS that are distinct from irisin levels in the control group of study participants who do not have PCOS. So, what we were looking for here is quantification — what were the irisin levels in the PCOS patients? And what were the irisin levels in the control group? The release doesn’t tell us. Instead, it says only that “teenagers with PCOS had significantly higher irisin levels compared to the control group.”
Establishing the superiority of a diagnostic test requires comparisons in much larger populations than were enrolled in this study.
Potential harms are not discussed. While a blood test is a relatively low-risk procedure, this release could have mentioned the risk of under- or over-diagnosis leading to incorrect or no treatment based on reliance of this diagnostic test, if it makes it to the commercial stage.
The release explains the study in concise terms, so it gets a borderline satisfactory rating. However, we do have one question that’s not addressed here. Some readers may have heard of irisin because it was referred to as the “exercise hormone” in some news coverage after its discovery in 2012. This is because research has found that irisin levels increase after physical exercise. Testosterone levels can also increase after physical exercise. The news release says that teens with PCOS had higher levels of irisin and testosterone, but doesn’t discuss exercise at all. The release does tell us that control and experimental groups were matched by age and BMI, but where they also matched by physical activity level? Is it possible that exercise may have skewed results, particularly given that this was a small study with only 40 participants? We don’t know, and the release doesn’t shed any light on the issue.
In addition, with such a small sample of study volunteers, there is limited ability to draw any conclusions about possible associations with exercise.
No disease mongering here. The release says that PCOS “is a common endocrine disorder affecting up to 12% of women” — and it’s not clear where they got the 12 percent number from. However, that’s not too far off from numbers we’ve seen elsewhere (as high as 10 percent, via NIH), and the language throughout the remainder of the release is responsible.
Funding sources and conflicts of interest are not mentioned at all. Even when it’s difficult to determine what any conflict of interest might be, it’s important to note where funding for health studies came from.
So, what are alternative means of diagnosing PCOS? The release doesn’t tell us. This is a particularly baffling oversight, since it would serve to place the research findings in context.
A common method of diagnosing PCOS is measurement of total or free testosterone levels over time in teenagers with abnormal menstrual patterns. Measurement of testosterone levels can be challenging because of the low levels found in women and a lack of widespread access to reliable testing.
The release notes that “Doctors are cautious when diagnosing PCOS in teenagers because the symptoms can be confused with normal pubertal changes” and that “the findings suggest that irisin could be a marker for PCOS allowing the condition to be diagnosed more easily.” But the release never tells readers how PCOS is diagnosed. As noted above, according to the Mayo Clinic, there is no definitive means of diagnosing PCOS. Instead, diagnosis is made based on the results of a variety of tests and symptoms. By noting this, the release could have highlighted how useful an irisin-based diagnostic procedure might be — if it ever comes to pass.
The release makes clear that it is too early to say whether irisin will serve as a good indicator for PCOS diagnosis.
The release refers to previous work regarding irisin and PCOS in adults, and that this is the first such study to look at irisin levels in teens.
The release uses language responsibly. It doesn’t say that this will be a valuable diagnostic tool, but that it is a promising first step. As a result, we give it a satisfactory rating. However, the release ends by referring to irisin’s potential as a drug target for future PCOS treatments. This is in a quote from a researcher, and is given in the context of “future directions” for the work, but it walks very close to the edge of “unjustifiable language” — primarily because, to the best of our knowledge, there is no research to support such a statement.