From the Guidelines
Menarche is considered late when it has not occurred by age 15, which is known as primary amenorrhea. This definition is based on the consensus statement from the British Journal of Sports Medicine 1. While the average age for first menstruation can vary, the key factor is whether menarche has occurred by age 15. If it hasn't, medical evaluation is recommended to identify any underlying causes and address potential issues related to bone health and fertility.
Factors Influencing Menarche
Several factors can influence the timing of menarche, including:
- Genetic predisposition
- Low body weight
- Excessive exercise
- Certain medical conditions like polycystic ovary syndrome or thyroid disorders
- Anatomical abnormalities
Evaluation and Treatment
Evaluation for delayed menarche typically involves:
- Physical examination
- Hormone level testing
- Possibly imaging studies Treatment depends on the underlying cause and may include hormone therapy if there's a hormonal imbalance, as noted in the context of relative energy deficiency in sport (RED-S) 1.
Importance of Addressing Delayed Menarche
Delayed menarche is important to address as it can impact bone health and fertility if left untreated. The definition of primary amenorrhea as no menarche by age 15 years 1 serves as a critical benchmark for when medical evaluation should be considered.
From the Research
Definition of Late Menarche
- Menarche is considered late if it has not occurred by 15 years of age or three years post-thelarche, as defined by primary amenorrhea 2.
Age of Menarche
- The mean age of menarche in contemporary US females is around 12.8 years, with African-Americans having menarche 0.6 years earlier 3.
- A late estrogenic stimulus, such as late menarche, can generate low bone mineral density 4.
Evaluation and Management
- Evaluation for primary amenorrhea should be considered if menarche has not occurred by 15 years of age or three years post-thelarche 2.
- Clinicians may consider etiologies of amenorrhea categorically, including outflow tract abnormalities, primary ovarian insufficiency, and hypothalamic or pituitary disorders 2.