Final answer:
In cases of thyrotoxicosis, a nurse should inquire about oligomenorrhea, the infrequent occurrence of menstruation, which is a likely change associated with an overactive thyroid or hyperthyroidism.
Step-by-step explanation:
Menstrual Cycle Changes in Thyrotoxicosis
When conducting a health history with a female client with thyrotoxicosis, which is an overactive thyroid condition, the nurse should inquire about changes in the menstrual cycle. Thyrotoxicosis can affect menstrual patterns due to its impact on metabolism and the reproductive system. The most relevant menstrual change to ask about in the context of hyperthyroidism would be oligomenorrhea, which is infrequent menstruation. Hyperthyroidism is known to potentially reduce menstrual flow and increase the length of the menstrual cycle, leading to fewer periods. On the other hand, menorrhagia, which is heavy or prolonged menstrual bleeding, is more commonly associated with hypothyroidism, and therefore would not be the expected change in a hyperthyroid state such as thyrotoxicosis.