Relative energy deficiency in sport and athlete nutrition — formative SAQs

SAQ 1 (10 marks) — The fifteen-year-old runner with shin pain and no period for four months

Stem: A fifteen-year-old competitive cross-country runner presents with six weeks of progressive right shin pain that now forces her to stop running, and her mother reports she has not had a menstrual period for four months. She trains six days a week and her mother believes her food intake has not changed despite the increased training. Her body mass index has fallen from the fortieth to the twenty-fifth centile over the year. She is afebrile, her heart rate is forty-eight beats per minute, and she has focal tibial tenderness. Outline your assessment, investigations, and management. ^{[9] [4]}

Model answer

Assessment and risk stratification (3 marks). This adolescent female endurance athlete has the classic Female Athlete Triad presentation — a bone stress injury, the secondary amenorrhoea of four months, and the falling body mass index that signals the low energy availability. The heart rate of forty-eight beats per minute is the bradycardia of the physiological down-regulation. The secondary amenorrhoea is defined as the absence of menses for three or more months, and it is the most reliable clinical marker of the energy deficit. The falling body mass index and the unchanged intake against the increased training point to the inadvertent undereating, and the energy availability is below the threshold. The fellowship skill is to treat every bone stress injury in a young female athlete as the tip of the energy-deficiency iceberg. ^{[9] [4]}

Investigations (3 marks). The endocrine laboratory tests confirm the functional hypothalamic amenorrhoea — the low or low-normal gonadotropins and the low oestradiol of the hypogonadotrophic hypogonadism — and exclude the mimics, with the prolactin, the thyroid-stimulating hormone, and the morning cortisol. The nutritional tests screen the ferritin for the iron deficiency and the 25-hydroxyvitamin D for the deficiency, with the sufficiency defined as fifty nanomoles per litre or above. The bone density is measured by the dual-energy X-ray absorptiometry at the lumbar spine and reported with the age-matched Z-score, never the T-score. The tibial pain is imaged with the magnetic resonance imaging, which reveals the bone marrow oedema of the stress reaction and the fracture line, because the high-risk site must be excluded and the delay risks the displacement. ^{[6] [9]}

Management (4 marks). The definitive management is the energy restoration as the first-line treatment, with the increase in the dietary intake toward the optimal energy availability of approximately forty-five kilocalories per kilogram of fat-free mass per day and the reduction in the training load. The Endocrine Society guideline frames the energy restoration as the first-line treatment for the functional hypothalamic amenorrhoea, and the combined oral contraceptive pill is not the first-line treatment because it does not restore the bone and it masks the menstrual signal. The calcium is optimised toward thirteen hundred milligrams per day for the adolescent, the vitamin D is supplemented to maintain the level at fifty nanomoles per litre or above, and the iron is supplemented when the ferritin is low. The tibial stress injury is managed with the protected weight-bearing and the graded rehabilitation, and the high-risk athlete is restricted from the training and the competition until the energy availability is restored, the menstrual function is recovering, and the bone is healed. The multidisciplinary team of the paediatrician, the dietitian, the psychologist, and the physiotherapist owns the clearance, and the premature return risks the recurrent fracture and the irreversible bone loss. ^{[6] [4]}