What is the best course of treatment for a 25-year-old woman with oligomenorrhea (infrequent menstrual periods) and irregular menstrual cycles ranging from 33 to 45 days?

From the Guidelines

The best course of treatment for a 25-year-old woman with oligomenorrhea and irregular menstrual cycles ranging from 33 to 45 days would typically be combined hormonal contraceptives (CHCs), such as oral contraceptive pills containing ethinyl estradiol and a progestin. Before initiating treatment, it's essential to rule out underlying causes such as polycystic ovary syndrome (PCOS), thyroid disorders, hyperprolactinemia, or premature ovarian insufficiency through appropriate laboratory testing including TSH, prolactin, and possibly testosterone levels 1.

Some key points to consider in the evaluation of this patient include:

• Menstrual irregularity, which can be assessed through a menstrual chart for at least 6 months, looking for patterns such as polymenorrhoea, oligomenorrhoea, or amenorrhoea 1
• The potential for PCOS, which is a common cause of irregular periods in women and can be indicated by low mid-luteal phase progesterone levels, hyperandrogenism, and polycystic ovaries on ultrasound 1
• The importance of assessing for other symptoms of endocrine disorders, including thyroid dysfunction, hirsutism, and galactorrhoea 1

If pregnancy is desired rather than cycle regulation, ovulation induction with medications like clomiphene citrate or letrozole might be more appropriate. For women who cannot use estrogen-containing products, cyclic progestin therapy can be used to induce regular withdrawal bleeding. CHCs work by suppressing ovulation and providing exogenous hormones that create a regular withdrawal bleeding pattern, addressing both the irregular cycles and potentially reducing long-term risks of endometrial hyperplasia associated with chronic anovulation.

It's also important to note that PCOS is a form of hyperandrogenic chronic anovulation, and its pathogenesis involves insulin resistance, hyperinsulinaemia, and downstream metabolic dysregulation 1. Therefore, lifestyle modifications, such as weight loss and exercise, may also be beneficial in managing PCOS and regulating menstrual cycles.

From the Research

Menstrual Cycle Irregularities

• A 25-year-old woman experiencing oligomenorrhea (infrequent menstrual periods) and irregular menstrual cycles ranging from 33 to 45 days may be diagnosed with polycystic ovary syndrome (PCOS) or other endocrine disorders 2.
• PCOS is a common cause of ovulatory dysfunction, characterized by estrogen levels within the normal range and oligo-/anovulation resulting in decreased progesterone levels 2.

Treatment Options

• Letrozole and clomiphene citrate are commonly used as first-line treatments for ovulation induction in PCOS women 3, 4.
• A study comparing letrozole and clomiphene citrate found that letrozole had excellent pregnancy rates compared to clomiphene citrate, with a higher monofollicular genesis and pregnancy rate in the letrozole group 4.
• Another study found that combination treatment of clomiphene citrate with letrozole may potentially improve fertility outcomes in PCOS subfertility, with higher post-ovulatory progesterone levels 3.

Thyroid Dysfunction and Hyperprolactinemia

• Women with PCOS do not suffer from thyroid dysfunction more often than controls, and the prevalence of positive anti-thyroid peroxidase antibodies (TPOab) is similar in both groups 2.
• The prevalence of hyperprolactinemia is also similar in women with PCOS compared to controls, with no increased risk of thyroid pathology or hyperprolactinemia in PCOS women 2.

Normal Menstrual Cycle

• The normal menstrual cycle in women is characterized by high variability in cycle length (26-35 days), with a fertile phase from 5 days before to the day of ovulation, and low fertility dependent on cycle length and age 5.
• The menstrual cycle is regulated by a complex interplay of hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone, with the corpus luteum playing a crucial role in the luteal phase 5.