This month, the 16-year-old's menstruation suddenly became very light.

At 16 years old, a sudden significant decrease in menstrual flow this month may be caused by irregular diet and作息 (daily routine), endocrine disorders, poor uterine development, or other factors. Patients can receive corresponding treatment based on their specific condition, as detailed below:

1. Irregular Diet and Daily Routine

If a 16-year-old patient excessively restricts food intake due to obesity, the body may lack essential nutrients, leading to prolonged malnutrition. This condition may disrupt normal menstruation and result in reduced menstrual flow. No special treatment is required; simply restoring a balanced diet will usually resolve the issue.

2. Endocrine Disorders

Endocrine disorders typically refer to hormonal imbalances within a woman's body. If progesterone and androgen levels fail to drop to appropriate levels before menstruation, the aforementioned symptoms may occur. Common causes of hormonal imbalance include stress and emotional suppression. Patients should visit a正规 hospital and, under medical guidance, take medications such as methimazole tablets or propylthiouracil tablets for treatment.

3. Poor Uterine Development

If a 16-year-old patient’s uterus or its associated structures have not developed normally—for example, due to congenital abnormalities—this may lead to decreased shedding of the endometrial lining during each menstrual cycle, resulting in reduced menstrual flow. In such cases, patients may undergo cervical dilation procedures as directed by a physician.

Besides the above, conditions such as uterine malformations, cervical canal stenosis, or polycystic ovary syndrome (PCOS) could also be responsible. It is recommended that patients promptly visit a正规 hospital and undergo appropriate examinations under medical supervision to avoid delays in diagnosis and treatment.