Which symptom would support a diagnosis of polycystic ovary syndrome (PCOS) in a female patient?

The presence of increased facial hair, also known as hirsutism, is a significant symptom that supports a diagnosis of polycystic ovary syndrome (PCOS). PCOS is characterized by hormonal imbalances, specifically elevated levels of androgens, which are male hormones found in both men and women. This excess of androgens can lead to the development of male-pattern hair growth in females, particularly on the face, chest, and back.

In contrast, regular menstrual cycles, weight loss, and low blood pressure do not align with the typical symptoms associated with PCOS. Women with PCOS often experience irregular menstrual cycles due to disrupted ovulation. Weight loss is generally not a symptom of PCOS, but rather a potential management strategy, as many individuals with the condition may struggle with weight gain or obesity. Low blood pressure is unrelated to the syndrome and does not indicate the hormonal or metabolic disturbances seen in PCOS.

Thus, increased facial hair is a classic symptom resulting from the hormonal changes associated with polycystic ovary syndrome, making it a strong indicator for diagnosis.