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Consider Relative Energy Deficiency in Sport (RED-S) as a Differential Diagnosis This High School Sports Season
Autumn is here and schools are back in session. Nationwide, nearly 8 million high school students will participate in organized sports this school year.1 Based on the rate of injury in high school athletes in the 2020–2021 school year we can anticipate that more than 13,000 high school athletes will suffer from an injury this school year.2 Of all these injuries 3.1% will occur in the foot.2
Some sports have rates of foot injury that are higher than average, including boys soccer, girls basketball, girls field hockey, boys lacrosse, girls lacrosse, girls track, boys cross country, girls cross country and girls cheerleading. The rate of injury to the foot in boys soccer and girls cross country is alarmingly high, accounting for 6.6% and 8.8% of all injuries respectively.2 In the majority of the country both boys soccer and girls cross country are fall season sports, so patients participating in these sports may soon be entering foot and ankle physicians’ offices across the country.
Relative Energy Deficiency in Sport (RED-S) is a physiological dysfunction syndrome disrupting many areas of normal physiological function.3 This syndrome is caused by a relative energy deficiency in which there is significant net negative daily caloric intake.3 This is common in high school athletes, who are burning large amounts of energy through sport training. Athletes may see improved performance initially as their body mass index (BMI) decreases due to the net negative calorie intake; however, a prolonged net negative caloric intake will lead to physiologic dysfunctions associated with RED-S.4
RED-S was formerly known as the female athlete triad due to the hallmark symptoms including low energy availability with and without disordered eating, amenorrhea, and osteoporosis.3 In 2014 the International Olympic Committee renamed the disorder to RED-S.3 RED-S still disproportionately affects female athletes; however, male and non-binary athletes may also be affected.3
As high school athletes suffer from foot and ankle injuries in the coming months, foot and ankle physicians should have a suspicion for RED-S when diagnosing and treating these athletes. As the most clinically significant physiological dysfunction of RED-S is osteoporosis, athletes suffering from RED-S typically present to foot and ankle physicians with stress fractures or avulsion fractures. One should thoroughly investigate for RED-S in all high school athletes presenting with symptoms or radiographic findings concerning for stress and avulsion fractures of the foot and ankle.
How RED-S Affects the Athlete
When Relative Energy Deficiency in Sport was initially recognized the thought was that the energy deficiency led to low estrogen production, leading to amenorrhea and decreased bone production.5 The theory was this was a primal survival mechanism, diverting energy away from metabolic processes not necessary for survival of the organism, and using this energy in processes necessary for survival such as muscular output.6 There are far more metabolic processes affected by RED-S than originally thought.7
Researchers now recognize that RED-S negatively impacts sexual function, bone health, endocrine function, metabolic function, hematological function, growth and development, psychological wellbeing, cardiovascular function, gastrointestinal function, and immunological function.3 The skeletal system is at particular risk for long-term effects of RED-S. The most important factor in maintaining bone density is to maximize peak bone density.8 High school athletes are at an age where their bone health is paramount to bone density throughout their lives. Most women reach their peak bone density in their early 20s, with some reaching peak density as early as age 18. Most men reach their peak bone density in their late 20s, but some may reach peak bone density in their early 20s.5 Compromised bone health during high school years will lead to low peak density and increased risk of osteoporosis and related sequelae such as fractures and stress fractures.8 The effects and long-term sequelae of RED-S on other metabolic functions are not fully understood.3
What Are the Symptoms of RED-S?
As discussed, high school athletes are at an age when bone density should not be in question. Any high school athlete presenting with abnormal fractures of foot or ankle bones, or stress fractures of foot or ankle bones, may have compromised bone health.3 Other symptoms that physicians should be wary of when considering a diagnosis of RED-S are as follows: increased injury risk, decreased coordination, decreased concentration, irritability, depression, decreased glycogen stores, decreased endurance, decreased muscle strength, and impaired judgement. There may also be more subtle signs pointing to symptoms of immune dysfunction, anxiety or depression, gastrointestinal issues such as heartburn, or irritable bowel.3
If your patients are showing any of the above signs or symptoms, you should have a low threshold for the diagnosis of RED-S. There is also a clinical assessment tool available through the International Olympic Committee (IOC). This clinical assessment tool assesses physique, eating habits, growth, metabolic and physiological functions, bone density, psychological complications, and length of RED-S.9
If there is any possibility that the patient is suffering from RED-S, a screening should take place. A thorough screening should begin by discussing the sport(s) that the athlete participates in. Sports where athletes may be judged on aesthetic or appearance, categorized by weight, or feats of endurance are particularly at risk for RED-S. Then one should question the patient’s injury history, including any recurrent injuries or illnesses. Discuss the patient’s ability in sport, including any decreased performance or performance variability.
Next, one should carefully and critically question the patient regarding disordered eating and weight loss. Assess the patient for normal growth and development, or cessation of growth and development and endocrine or sexual dysfunction. Finally, question the patient regarding any psychological disturbances or recent mood changes.9 The answers to this thorough screening can easily be applied to the IOC Clinical Assessment tool and used to dictate proper treatment, all while building trust and rapport with the patient.9
Treatment of RED-S
Keep in mind that the patient likely presented to your office because he or she is injured. The patient will feel a high pressure from coaches, teammates and possibly parents to continue participation in sport. Set the stage for treating RED-S by treating the presenting injury as you normally would. Address the treatment of RED-S in addition to your primary treatment plan.
The first and most important step in the treatment of RED-S is accurate diagnosis. Following diagnosis it is recommended that a multi-specialty team begins treating the patient immediately.9 The first step in treatment is explaining the diagnosis and potential long term effects of RED-S. Then, using the aforementioned clinical assessment tool, categorize the patient appropriately. The IOC RED-S clinical assessment tool categorizes patients into risk levels as low risk, moderate risk and high risk.9 Remove high-risk patients from all sport participation.9 Clear moderate-risk patients for sport participation only if they are able to be closely supervised and receive a medical treatment plan.9 Low-risk patients may fully participate in sports.9 Patients of any risk level should have a full exam by a multidisciplinary team including the primary care physician, psychiatrist or psychotherapist, exercise physiologist, dietician and foot and ankle physician.9 Providing the patient with appropriate resources and referrals to other specialists is critical in ensuring that the patient does not continue to suffer from RED-S and returns to sport at the appropriate time.9
Conclusion
All foot and ankle physicians should be aware of the signs, symptoms, and potential long term sequelae of Relative Energy Deficiency in Sport. Any high school athlete presenting for treatment of suspected fracture or abnormal stress fracture should raise concerns of possible RED-S physiological derangement taking place. One should accurately screen the patient for RED-S, and if the screening is positive or questionable, utilize the IOC clinical assessment tool to categorize the patient’s risk level. Following risk level categorization, give the patient referrals to all appropriate medical staff for proper treatment. The patient should also not participate in sport following the IOC clinical assessment tool recommendations, in addition to the presenting injury.
As physicians it is our responsibility to treat all patients to the best of our abilities, which includes advocating for proper removal from sport to address all diagnoses.
For related reading on RED-S, see this April 2022 feature from Podiatry Today.
Dr. Miller is a Fellow of the American College of Foot and Ankle Surgeons. He is the Director of the Pennsylvania Intensive Lower Extremity Fellowship in Malvern, PA, and the Podiatric Residency Program at Phoenixville Hospital in Phoenixville, PA.
Dr. Biscorner is a second-year resident with the Phoenixville Hospital/Tower Health residency program in Phoenixville, Pa.
Dr. Kotzeva is a current Fellow of the Pennsylvania Intensive Lower Extremity Fellowship in Malvern, PA.
References
1. Participation in high school sports registers first decline in 30 years. NFHS. (n.d.). Retrieved September 18, 2022, from https://www.nfhs.org/articles/participation-in-high-school-sports-registers-first-decline-in-30-years/
2. Collins C, Robinson H, Burus T. (2021, February 24). Convenience Sample Summary Report NATIONAL HIGH SCHOOL SPORTS-RELATED INJURY SURVEILLANCE STUDY 2020-21 School Year. Retrieved from https://www.datalyscenter.org/sites/datalyscenter.org/files/2020-21_High_School_RIO_CONVENIENCE_Summary_Report.pdf.
3. Mountjoy M, Sundgot-Borgen JK, Burke LM, et al. IOC consensus statement on Relative Energy Deficiency in Sport (RED-S): 2018 update. Br J Sports Med. 2018; 52(11):687–697. https://doi.org/10.1136/bjsports-2018-099193
4. Lodge MT, Ackerman KE, Garay J. Knowledge of triad and RED-S in female cross-country athletes and support staff. J Athl Train. 2021. Online ahead of print. doi: 10.4085/1062-6050-0175.21.
5. Boutari C, Pappas P, Mintziori G, et al. The effect of underweight on female and male reproduction. Metabolism. 2020;107:154229. doi: 10.1016/j.metabol.2020.154229.
6. Dave SC, Fisher M. Relative energy deficiency in sport (RED-S). Curr Probl Pediatr Adolesc Health Care. 2022; 52(8):101242. https://doi.org/10.1016/j.cppeds.2022.101242
7. Sangenis P, Drinkwater B, Loucks A, Sherman R, Sundgot-Borgen J, Thomspon R. Position stand on the female athlete triad. Lausanne, Switzerland: IOC Medical Commission Working Group of Women in Sport, 2005.
8. Williams NI, Koltun KJ, Strock NCA, De Souza MJ. Female athlete triad and relative energy deficiency in sport: a focus on scientific rigor. Exerc Sport Sci Rev. October 2019; 47(4):197–205.
9. Mountjoy M, Sundgot-Borgen J, Burke L, et al. RED-S CAT. Relative energy deficiency in sport (RED-S) Clinical Assessment Tool (CAT). Br J Sports Med. 2015; 49(7):421–423. https://doi.org/10.1136/bjsports-2014-094559
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