IOC REDs CAT2 Severity/Risk Assessment Tool that implements primary, secondary and potential indicators into a traffic-light criterion outlined in figure 2
| REDs indicator | References |
| Severe primary indicators (count as two primary indicators) | |
| Primary amenorrhea (Females: primary amenorrhea is indicated when there has been a failure to menstruate by age 15 in the presence of normal secondary sexual development (two SD above the mean of 13 years), or within 5 years after breast development if that occurs before age 10; or prolonged secondary amenorrhea (absence of 12 or more consecutive menstrual cycles) due to FHA | 5 39 51 163 181 |
| Clinically low free or total testosterone (Males: below the reference range) | 53 82 83 182–184 |
| Primary indicators | |
| Secondary amenorrhea (Females: absence of 3–11 consecutive menstrual cycles) caused by FHA | 5 39 51 163 |
| Subclinically low total or free testosterone (Males: within the lowest 25% (quartile) of the reference range) | 53 82 83 182–185 |
| Subclinically or clinically low total or free T3 (within or below the lowest 25% (quartile) of the reference range) | 53 182 186 |
| History of ≥1 high-risk (femoral neck, sacrum, pelvis) or ≥2 low-risk BSI (all other BSI locations) within the previous 2 years or absence of ≥6 months from training due to BSI in the previous 2 years | 39 115 |
| Pre-menopausal females and males <50 years old: BMD Z-score* <-1 at the lumbar spine, total hip, or femoral neck or decrease in BMD Z-score from prior testing Children/adolescents: BMD Z-score* <−1 at the lumbar spine or TBLH or decrease in BMD Z-score from prior testing (can occur from bone loss or inadequate bone accrual). | 116 117 119 120 |
| A negative deviation of a paediatric or adolescent athlete’s previous growth trajectory (height and/or weight) | 174 175 |
| An elevated score for the EDE-Q global (>2.30 in females; >1.68 in males) and/or clinically diagnosed DSM-5-TR-defined Eating Disorder (only 1 primary indicator for either or both outcomes) | 122 124 130 133 134 187 |
| Secondary Indicators | |
| Oligomenorrhea caused by FHA (>35 days between periods for a maximum of 8 periods/year) | 5 39 51 163 |
| History of 1 low-risk BSI (see high vs low-risk definition above) within the previous 2 years and absence of <6 months from training due to BSI in the previous 2 years | 39 115 |
| Elevated total or LDL cholesterol (above reference range) | 81 135 139 |
| Clinically diagnosed depression and/or anxiety (only 1 secondary indicator for either or both outcomes) | 33 124 188 |
| Potential Indicators (not scored, emerging)† | |
| Subclinically or clinically low IGF-1 (within or below the lowest 25% (quartile) of the reference range) | 182 189 190 |
| Clinically low blood glucose (below the reference range) | 130 189 |
| Clinically low blood insulin (below the reference range) | 23 24 182 |
| Chronically poor or sudden decline in iron studies (eg, ferritin, iron, transferrin) and/or haemoglobin | 17 191–193 |
| Lack of ovulation (via urinary ovulation detection) | 26 51 65 162 |
| Elevated resting AM or 24-hour urine cortisol (above the reference range or significant change for an individual) | 23 24 182 194 |
| Urinary incontinence (Females) | 195–197 |
| GI or liver dysfunction/adverse GI symptoms at rest and during exercise | 27 34 198 |
| Reduced or low RMR <30 kcal/kg FFM/d or RMR ratio <0.90 | 153 158 186 199 |
| Reduced or low libido/sex drive (especially in males) and decreased morning erections | 28–30 36 |
| Symptomatic orthostatic hypotension | 171 174 200 |
| Bradycardia (HR <40 in adult athletes; HR <50 in adolescent athletes) | 171 174 175 |
| Low systolic or diastolic BP (<90/60 mm Hg) | 172 176 |
| Sleep disturbances | 75 201 202 |
| Psychological symptoms (eg, increased stress, anxiety, mood changes, body dissatisfaction and/or body dysmorphia) | 27 32 33 122 124 188 |
| Exercise dependence/addiction | 122 130 203 204 |
| Low BMI | 39 174 175 |
Every indicator below requires consideration of a non-LEA-mediated differential diagnosis. All indicators apply to females and males unless indicated. Menstrual cycle status and endogenous sex hormone levels cannot be accurately assessed in athletes who are taking sex hormone-altering medications (eg, hormone-based contraceptives), and thyroid hormone status indicators cannot be accurately assessed in athletes who are taking thyroid medications. All laboratory values should be interpreted in the context of age-and sex-appropriate and laboratory-specific reference ranges. Most REDs data and associated thresholds have been established in pre-menopausal/andropausal adults unless indicated. Disclaimer: This tool should not be used in isolation nor solely for diagnosis, as every indicator requires clinical consideration of a non-LEA-mediated differential diagnosis. Furthermore, the tool is less reliable in situations where it is impossible to assess all indicators (eg, menstrual cycle status in females who are using hormonal contraception). This tool is not a substitute for professional clinical diagnosis, advice and/or treatment from a physician-led team of REDs health and performance experts.
*BMD assessed via DXA within ≤6 months. In some situations, using a Z-score from another skeletal site may be warranted [eg, distal 1/3 radius when other sites cannot be measured or including proximal femoral measurements in some older (>15 years) adolescents for whom longitudinal BMD monitoring into adulthood is indicated].119 121 A true BMD decrease (from prior testing) is ideally assessed in comparison to the individual facilities DXA’s Least Significant Change (LSC) based on the facilities calculated coefficient of variation (%CV). As established by ISCD, at the very least, LSC should be 5.3%, 5.0% and 6.9% for the lumbar spine, hip and femoral neck to detect a clinical change.120 121
†Potential indicators are purposefully vague in quantification, pending further research to quantify parameters and cut-offs more accurately.
Adolescent, <18 years of age; BMD, bone mineral density; BMI, Body Mass Index; BP, blood pressure; BSI, bone stress injuries; DSM-5-TR, Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision; DXA, dual-energy X-ray absorptiometry; EDE-Q, Eating Disorder Examination Questionnaire; FFM, fat-free mass; FHA, functional hypothalamic amenorrhea; GI, gastrointestinal; HR, heart rate; IGF-1, insulin-like growth factor 1; kcal, kilocalories; LDL, low-density lipoprotein; RMR, resting metabolic rate; T3, triiodothyronine; T, testosterone; TBLH, total body less head.