Everything in Moderation: What the Female Athlete Triad Teaches Us About Energy Balance

Case Report

A 26-year-old woman presents for her routine annual examination. She shares that as a teen she had anorexia nervosa. She went through a variety of treatments, including psychotherapy, nutrition counseling, and pharmacotherapy with a selective serotonin reuptake inhibitor. She never required hospitalization for her eating disorder. She was able to swim competitively in college. On further questioning, she admits that she remains restrictive with her eating; she is very conscious of her caloric intake and only allows herself 1600 calories daily. She does not purge or use laxatives but she swims, runs, and practices yoga, doing most activities almost daily. Her last menses was 7 months ago; she has not been sexually active for over a year. Her body mass index (BMI) today is 20.5 mg/kg². In addition to laboratory evaluation for secondary amenorrhea, which of the following tests may be considered?

A. Ultrasound of the pelvis

Discussion

The Female Athlete Triad (the Triad) is a disorder best described as the relationship between low energy availability usually related to disordered eating, menstrual dysfunction and decreased bone mineral density (BMD). Prior descriptions of the Triad have been rigid, only including disordered eating, amenorrhea, and osteoporosis. ^1,2 However, the American College of Sports Medicine (ACSM) updated this definition in their Position Stand in 2007, and redefined the Triad as the interrelationship between energy availability, menstrual function, and bone mineral density. ³ The Triad applies not only to teenage and college-aged female athletes, but also to other menstruating exercising women. Importantly, all three elements of the Triad may not manifest simultaneously, and the consequences may not become apparent until later in life. ²

Disordered eating is the initial component of the Triad. Disordered eating describes a broad spectrum of often pathologic weight control behaviors, ranging from fasting and calorie restriction to frank anorexia nervosa or bulimia nervosa. ⁴ It is this restriction of calories in disordered eating that leads to the energy mismatch in exercising women that is now understood to underlie the Triad. The 2007 ACSM Position Stand recognizes low energy availability as the driving factor behind the other components of the Triad. ³ Energy availability is the dietary energy that is available after exercise for use by the body for all other physiologic functions. ^5,6 Energy availability below 30 kcal/kg lean body mass (LBM), which is near resting metabolic rate, disrupts luteinizing hormone (LH) pulsatility and impairs bone turnover. ⁵ Frequently female athletes restrict their energy availability below this threshold. In one study of female collegiate soccer players, a sport not normally associated with disordered eating, up to one-third of the team demonstrated low energy availability (<30 kcal/kg LBM) at some point during the season. ⁷

Menstrual disorders in the Triad may vary, and include anovulation, oligomenorrhea, and luteal phase defects. Patients commonly experience functional hypothalamic amenorrhea, due to reduced production of the gonadotropin-releasing hormone (GnRH) and in turn, LH levels. ⁶ Blood tests in these patients show reduced follicle stimulating hormone (FSH), LH, and estrogen levels. There may not be withdrawal bleeding with a progesterone challenge. ⁸ This hypoestrogenism not only causes menstrual irregularities, but also leads to increased risk for cardiovascular disease and reduced BMD. ⁹

The third part of the Triad is decreased bone mineral density. When considering the Triad in a premenopausal athlete, assessment of BMD should use the Z-scores of age-matched individuals in dual-energy X-ray absorptiometry (DEXA), as T-scores are unreliable in this age group. ¹⁰ Despite the younger age of most patients with the Triad, decreases in bone density do exist. In a study of college athletes from a variety of sports, the prevalence of Z-scores less than −1.0 was 12%. ⁴ Decreased bone mineral density in Triad patients results from both reduced bone formation and increased bone resorption. The reduced bone formation is due to prolonged energy mismatch from inadequate nutritional intake, leading to a decrease in bone trophic factors, vitamins, and micronutrients. ¹ Estrogen protects the skeleton from bone resorption, so women with the Triad who have hypoestrogenism will have increased bone turnover, further worsening their BMD.

The management and treatment of patients with the Triad first requires recognition of the syndrome. Once identified, the cornerstone of treatment is increasing energy availability, through increased caloric intake and reduced caloric expenditure. This is best achieved by a multidisciplinary approach with sports medicine, mental health professionals, and dieticians. The treatment goal should be natural restoration of menses and improvement in BMD. ⁶ Simple weight gain has been shown to improve bone mineral density in patients with prolonged amenorrhea. ^11,12 Caloric intake of at least 30–45 kcals/kg LBM has been recommended for successful treatment. ⁹ Supplementation with calcium and vitamin D is also recommended. ^5,9 Significant changes in BMD can be seen within 3 months of nutritional rehabilitation, with further increases if a healthy weight can be sustained for 12 months. ¹² This improvement in BMD can be observed even without resumption of menses. ¹¹ Although return of menses may be used as a measure of clinical improvement, weight gain of any amount in these patients is beneficial for bone health and should be encouraged.

There has also been interest in the use of pharmacotherapy to treat individual components of the triad. Regarding direct treatment of reduced BMD, bisphosphonates are not advised in premenopausal women due to their prolonged half-life within the bone and potential teratogenic effects. ¹³ The role of combined oral contraceptives (COC) to treat menstrual irregularities and low BMD is controversial. There is currently insufficient evidence to suggest improvement in BMD or reduction in fracture risk in patients who are treated with COC. ^8,9,13 Though regular withdrawal bleeding is reestablished in some patients through the use of COC, usage is also associated with disadvantages such as premature closure of the epiphyses in the young athlete, ¹⁴ and a false sense of security that the withdrawal bleeding induced by the use of COC is actually a return of menstrual cyclicity. ^6,8 Because BMI norms are not helpful in identifying adequate weight ranges, the importance of observing the return of menstrual cyclicity as a marker of adequate nutrition cannot be overstated. Monthly withdrawal bleeds induced by the use of COCs, or absence of bleeding with continuous usage, obscures the presence or absence of the underlying menstrual cycle and may encourage the patient to stabilize at a weight that remains too low to support full recovery. ¹⁵

Treatment as described may appear straightforward; however, psychological barriers may be difficult to overcome. ⁶ It is likely that the patient in this vignette, for instance, continues to have a serious eating disorder. Perfectionism, high self-motivation, compulsiveness, and competitiveness can be personality traits seen at this level of athleticism, ^1,6 which is why a multidisciplinary treatment team including a psychologist is recommended. ^3,6,9 Patients may have desire to exercise at high intensity or for long duration. ⁹ Minimizing the emphasis on exercise restriction and instead focusing on cross-training, resistance or balance activities that require less energy expenditure may be a helpful strategy. ¹⁴

Answer: The Correct Answer is B

Bone mineral density assessment should be considered, as this patient is at high risk for decreased BMD. Her prior history of anorexia during her teens may have compromised her attainment of peak bone mass. Current energy imbalance is further exacerbating bone loss. If the patient does have decreased BMD, then she would meet criteria for the Female Athlete Triad.

Ultrasound of the pelvis, MRI of the pituitary gland, and the thyroid scan are not correct answers, unless laboratory evaluation for secondary amenorrhea reveals polycystic ovary syndrome (PCOS), hyperprolactinemia, or hyperthyroidism, respectively. Routine screening mammography is not indicated in a woman of this age.

The primary care setting offers an opportunity to both identify patients at risk for this disorder and to recommend referral for appropriate treatment.