Hair loss is common after metabolic and bariatric surgery especially in younger women, and those with low serum levels of zinc, folic acid and ferritin, according to researchers reporting on behalf of Global Bariatric Research Collaborative. The found that approximately 57% of patients experience hair loss after surgery and large, randomised studies are needed to research this issue further. The findings were published in the paper, ‘Hair Loss After Metabolic and Bariatric Surgery: a Systematic Review and Meta-analysis’, featured in Obesity Surgery.
The paper’s authors noted that hair loss is a common complication after surgery and there is a paucity of published systematic review in the scientific literature. Therefore, they undertook this systematic review and meta-analysis (PubMed, CINAHL, EMBASE, Web of Science, SCOPUS, and four Chinese databases were searched) on hair loss after bariatric surgery in accordance with Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines.
Only articles that referenced patients with body mass index (BMI) greater than 30 kg/m2, age 18–65 years and that provided the incidence of hair loss after MBS or its etiological factors. They identified 18 eligible studies (n. of patients=2538) published between 2011–2020, including one randomised controlled trial, three prospective observational studies, eight retrospective observational studies and five cross-sectional studies (duration of follow-up ranges from one to 72 months). Only four studies analysed the influencing factors of hair loss after surgery.
The overall incidence of hair loss ranged from 4.5% to 80%, however due to the significant heterogeneity from the studies – the pooled results revealed an incidence of 57%of hair loss. A subgroup analyses by follow-up duration (≥ 12 months vs. < 12 months). When the investigators examined subgroups based on follow-up duration, they found that the incidence of hair loss decreased with longer follow-up times, which decreased from 58% <12 months to 35% >12 months. An additional subgroup on procedures found that the incidence of hair loss was similar in both sleeve gastrectomy (51% (48 to 54%), p< 0.1) and RYGB (59% (55 to 63%), p<0.1) surgical groups.
In the five studies that examined the factors related to hair loss after surgery, 783 patients were included (419 hair loss patients and 364 controls). Four studies were included in the meta-analysis of zinc (701 patients), which revealed that zinc concentration was lower in patients with hair loss after surgery (p=0.05, follow-up 6.8 months to 15 months).
A total of three studies examined serum iron levels and found that there were no significant differences in serum iron levels between patients with or without hair loss after surgery (p=0.24). Two studies looked at serum ferritin levels, with both showing lower levels in patients reporting hair loss after surgery (p=0.01).
Two studies reported the outcome of folic acid levels, and revealed levels were lower in patients with hair loss (p<0.0001). The overall analysis reported lower vitamin B12 levels in patients reporting hair loss (p=0.51).
“The evidence remains inconclusive to support any association with low iron or vitamin B12 levels,” they noted.
Finally, hair loss after surgery was more common in women (p=0.08) and patients with hair loss were younger than controls (p=0.008).
“To our knowledge, this is the first systematic review and meta-analysis on hair loss after bariatric surgery,” the authors concluded. “Our findings could prove helpful in the diagnosis and treatment of these patients. Larger, randomised studies are needed.”
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