Alopecia areata (AA) is a relatively common cause of hair loss, affecting 1%-2% of the US population. Although it is understood that autoimmunity plays a key role in its pathogenesis, it is unclear whether the condition is associated with other autoimmune conditions, including thyroid disorders. As a result, screening practices vary widely. Medscape spoke with Dr Andrew Bauer, director of The Thyroid Center at The Children's Hospital of Philadelphia (CHOP), and Dr Leslie Castelo-Soccio, research director of the section of dermatology at CHOP, coauthors of a new paper that addressed this question, about their study and their key findings.
Medscape: Can you briefly review the epidemiology and incidence of AA? Are there particular populations of kids that are most affected?
Leslie A. Castelo-Soccio, MD, PhD: AA is a common autoimmune disease. The lifetime incidence is about 2% worldwide, with a prevalence of about 0.1%-0.2%. Girls and boys, men and women, are equally affected. There is a slightly higher incidence in individuals with Down syndrome. If you have another autoimmune disease, you're more likely than the general population to develop AA.
Medscape: Historically, what has been the approach to the evaluation of kids with AA?
Dr Castelo-Soccio: The evaluation is a clinical one that includes a thorough skin exam, a personal and family medical history, and a good review of systems. This review of systems targets the most common secondary autoimmune diseases that we see with alopecia areata, which include thyroid disease, type 1 diabetes, and pernicious anemia. On the basis of these, I make a decision about whether or not to conduct thyroid function testing. However, because there is no guideline, many children will get screens for all possible autoimmune diseases.
Medscape: Can you describe the methodology used for your study? You note that hair loss in the children was classified as mild, moderate, or extensive. Was that determination made by the treating clinicians, or by you as the study authors after a retrospective review of the charts?
Dr Castelo-Soccio: A Severity of Alopecia Tool score is calculated for every patient who is seen for AA at our center, and that is performed at the time of a child's visit. This tool was created as a clinical and research tool by Dr Elise Olsen and colleagues in the 1990s and is the gold standard for AA. The tool was updated last year. In our paper, we classified hair loss involving less than 25% of the scalp as mild, 26%-50% involvement as moderate, and greater than 50% scalp involvement as severe.
Medscape: You noted that the approach to assessment of children with AA varies widely. Does the use of this tool also vary?
Dr Castelo-Soccio: It is consistently used in specialty hair clinics and for clinical trials. However, it is a pretty cumbersome tool that takes time to perform consistently. General dermatology clinics, as a rule, will not use this scoring system but will categorize alopecia severity as mild, moderate, or severe and type as patchy, ophiasis pattern, totalis, or universalis.
Medscape: In your study, you found that less than one half (298 of 751) of children seen for AA had received thyroid function screening. Do these two populations—screened and unscreened—differ in any meaningful way?
Dr Castelo-Soccio: We did not identify any differences between the populations. The only exception was that patients with Down syndrome were more likely to be screened before being seen in our clinic. Other factors that can influence screening include a finding on the review of systems, parental requests for screening, or screening ordered by the child's primary care physician before their presentation to our clinic.
Medscape: How representative of the general population was your study population? Do you believe that you see children with more extensive disease because you are such a large referral center?
Dr Castelo-Soccio: I think our population is actually pretty representative and diverse. Most of the children we see have just patch-stage alopecia, the mildest form of AA. Only about 7%-8% of patients with AA will have the most severe forms—alopecia totalis, which is loss of all scalp hair, or alopecia universalis, which is loss of all scalp plus other body hair. In our study, about 19% of patients had the more severe forms. Although that is a somewhat higher percentage than the overall alopecia areata population, our study did not comprise exclusively children with severe alopecia. One other thing to note is that our study population was very ethnically diverse, which is reflective of the patients seen at CHOP.
Medscape: AA can be a pretty distressing condition for both children and families. Do most of these kids end up being referred to a dermatology practice?
Dr Castelo-Soccio: Yes. Sudden loss of hair is distressing for children and their family. Many children with patches of hair loss as small as a few millimeters often are referred because of the concern that there is an underlying systemic problem, with hair loss as an external manifestation.
Medscape: What were your key findings regarding the utility of screening AA patients for thyroid disorders?
Andrew J. Bauer, MD: Patients with one autoimmune disease are at risk of having additional forms of autoimmune disease. So, patients with AA are at increased risk of having autoimmune thyroid disease. The most important finding in our study is that we identified a subpopulation of patients with AA for whom thyroid screening would be most appropriate.
Screening should be done in patients with Down syndrome, a personal history of atopy, a family history of thyroid disease, or findings on exam that suggest that the thyroid also may be part of the clinical picture. Screening should consist of thyroid-stimulating hormone (TSH) and free thyroxine (T4) levels. If the TSH level is elevated, additional testing, to include thyroid autoantibody levels, may be ordered to confirm the diagnosis of autoimmune hypothyroidism.
As you reviewed, developing AA is stressful, and both the patient and the providers are looking for an answer and a cure. Clinicians are empathetic, and because there isn't an effective treatment for AA, additional lab tests are often ordered to look for other disorders that may have similar signs and symptoms. Screening for hypothyroidism is one of the most frequent avenues to pursue, because hypothyroidism may be associated with altered hair growth and/or strength. Unfortunately, although thyroid hormone replacement may improve hair strength in patients with primary hypothyroidism, there is no evidence to support that treatment with thyroid hormone improves AA.
Dr Castelo-Soccio: We see thousands of patients with alopecia areata, and the majority do not have any thyroid disease and will not develop thyroid disease over their lifetime. One goal of this study was to provide evidence to direct that decision-making regarding initial screening of patients.
Medscape: Is the age of the child a factor in making a decision to screen?
Dr Castelo-Soccio: Age can be factor in the lifetime severity of disease. It is thought that children who present under the age of 3 years are more likely to progress to the more severe forms. However, our study did not find that children with the most severe variant of AA were at higher risk for parallel thyroid disease.
Medscape: Where should screening occur: the primary care setting, or a dermatology practice?
Dr Castelo-Soccio: The message for both primary care providers and dermatologists is the same. We tend to see a lot of extra tests being performed that are not needed. Selecting whom to screen even before a referral is important.
As Dr Bauer noted, some of the testing is done owing to the provider and family's desire to find a "fixable" underlying etiology. We know the cause has a genetic basis within the immune system. But we do not know what triggers the onset or how to permanently turn off this overactive immune process. Whereas scientists continue to add to this knowledge and identify potential new therapies, families often are looking for a fix. Many times, there are questions about diet and thyroid hormone replacement. The search for an answer and a treatment is why some testing gets performed.
Medscape: Are there any other key messages from your study?
Dr Bauer: I would like to reemphasize that appropriate screening involves selecting the right patient and performing the right tests. TSH and free T4 measurement is an adequate initial thyroid screen. Thyroid antibody titers are not indicated. We do not initiate thyroid hormone replacement in children with a normal TSH level and positive antibodies. The TSH is the actionable level. The decision to initiate treatment is based on whether or not that child may benefit from thyroid hormone for their thyroid condition; it is not to improve their alopecia. Although AA is an associated disorder, thyroid disease is not the cause of the AA, and there is no evidence to suggest that thyroid replacement therapy will improve AA.
One other point I'd like to make is in regard to use of biotin, an over-the-counter (OTC) supplement that is marketed to improve nail and hair growth. Families often initiate OTC supplements on their own, and clinicians may forget to ask about their use. Whether biotin works is not known, but what parents and patients on biotin need to know is that they should stop taking biotin 48-72 hours before testing thyroid function, owing to cross-reactivity between high biotin levels and the detection reagents used to measure TSH, triiodothyronine (T3), and T4. Biotin can lead to falsely elevated T3/T4 levels and a low TSH, labs that resemble hyperthyroidism. Biotin can also cross-react with several other endocrine lab tests. The US Food and Drug Administration recently issued a warning to clinicians to be aware of biotin's interference with a range of lab tests.
Dr Castelo-Soccio: I recently completed a review on use of biotin for hair loss. There is no evidence that, in the absence of a biotin enzyme deficiency, biotin helps with hair regrowth. I do not routinely recommend biotin supplementation, but if a family wants to use it, I usually do not oppose its use because it is a low-risk supplement.
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Cite this: Alopecia Areata: Which Kids Should You Screen for Thyroid Disease? - Medscape - Jan 02, 2018.