Having irregular, inconsistent, and unpredictable menstrual cycles can be a frustrating and concerning issue for many people. Some change in menstrual flow is normal at menarche, postpartum, or in the perimenopausal period, Irregular menstrual cycles (also called oligomenorrhea) are when a person reports their cycle length is greater than 35 days or they have 4-9 menstrual cycles in a year.

Oligomenorrhea should be properly evaluated and managed ideally with a collaborative inter-professional team to meet a person’s unique needs and prevent complications that may arise from not having regular ovulatory cycles.

Causes of oligomenorrhea?

Oligomenorrhea is often a sign of underlying disease. Irregular menstrual cycles can be caused by a variety of factors, including stress, hormonal imbalances, and certain medical conditions.

The following may be causes of oligomenorrhea:

• Polycystic ovarian disease
• Androgen secreting tumor of the ovary
• Androgen secreting tumor of the adrenal gland
• Cushing syndrome
• Hyperthyroidism
• Prolactinomas
• Hypothalamic amenorrhea
• Pelvic inflammatory disease
• Asherman syndrome
• Uncontrolled diabetes mellitus
• Type-1 diabetes mellitus
• Congenital adrenal hyperplasia
• Non-classic congenital adrenal hyperplasia.
• A side effect of oral contraceptive pills
• Antipsychotic medication use
• Antiepileptic medication use
• Anatomic problems
• Primary ovarian insufficiency
• Exercising women with polycystic ovarian disease

History of Irregular Periods

Your healthcare provider may ask you a detailed history of your menstruation via a series of questions relating to your experience of menstrual cycle disturbances. You may be asked about:

• The days of normal flow
• The number of pads/tampons you use or the volume in your menstrual cup you observe per day
• The interval between two menstrual cycles
• The regularity of your previous menstrual cycles
• Your age when you got your very first period (menarche)
• Any sexual unprotected intercourse
• Abdominal pain
• Discharge
• Weight loss or general weight changes
• Recent changes in voice tone, hair growth, acne, blur vision, headaches, sexual drive/libido, milky discharge from nipples, bowel habits
• Your use of medications such as birth control pills, antipsychotics, antiepileptics, and steroids
• Family history (especially first-degree relatives)

These details can provide can your healthcare team an idea about the amount of bleeding, the number of cycles in a year, and the regularity of menstrual cycles that will help to diagnose the underlying issue behind your irregular periods. Irregularities of bleeding between menstrual cycles, hot flashes, night sweats must also be ruled out. The above information can help us to know the baseline pattern of bleeding in patients and the severity of change in that pattern.

Laboratory Evaluation for Oligomenorrhea

Laboratory investigations to evaluate the cause of your irregular periods may include the following:

Blood Tests

Pregnancy Test

In a person who is sexually active, confirming pregnancy status via urine (at-home pregnancy tests) and/or a blood pregnancy test is the first step (or one of the first steps) in investigating a missing period.

Complete Blood Count and Differential

One common lab test that your healthcare provider may recommend is a complete blood count (CBC). This test looks at the number and types of cells in your blood and can help identify any underlying infections or illnesses that may be contributing to irregular cycles. If your CBC results show that you have anemia, for example, your healthcare provider may recommend iron supplements to help improve your overall health and regulate your menstrual cycle.

Thyroid function tests

Another common lab test is a thyroid function test. This test measures the levels of thyroid-stimulating hormone (TSH) and thyroid hormones (free T3, free T4) in your blood and can help identify any issues with thyroid function that may be causing irregular cycles. An overactive thyroid (indicated by decreased TSH levels), for example, can cause periods to become lighter or less frequent, while an underactive thyroid (indicated by increased TSH levels) can cause periods to become heavier or more frequent. In cases were autoimmunity is suspected, the presence of thyroid autoantibodies may also be assessed.

Pituitary and Ovarian Hormones

If hormonal disorders relating to your brain-ovaries’ feedback system are suspected, your healthcare provider may recommend running a hormone panel. This can include tests to measure levels of your ovarian hormones (estrogen, progesterone, total and free testosterone) and your pituitary hormones [luteinizing hormone (LH), and follicle-stimulating hormone (FSH)] at different points in your cycle.

Prolactin, which is a hormone that helps with milk production, may also be tested. Prolactin affects cycle regularity by inhibiting the secretion of FSH. The mechanisms that cause thyroid-stimulating hormones (TSH) to rise can also lead to an elevation of prolactin, which is why both are important to test.

Hormonal disorders (specifically pertaining to sex hormones) can lead to irregular cycles, as well as other symptoms like acne, mood swings, and weight gain.

Metabolic Markers

If issues relating to glycemic control (i.e. blood sugar regulation) are suspected, testing your hemoglobin A1C (HbA1C) levels, alongside your fasting blood glucose, may be recommended.

Other Blood Tests Not Part of Standard of Care for Oligomenorrhea

Adrenal Hormones (Cortisol, DHEA-S)

Your adrenal function, which is primarily involved in your stress/adaptation response, is connected to your menstrual health. Your provider may order a morning adrenocorticotropic hormone and cortisol test via blood or 4-point urinary cortisol and cortisone with DHEA-S.

Vitamin D (25-hydroxy vitamin D or 25(OH)D) test

While not part of standard of care for oligeomenorrhea, there seems to be a demonstrable relationship between the frequency of menstrual disorders and low levels of Vitamin D.

Investigations

In some cases, your healthcare provider may also recommend imaging tests, such as:

• An abdominal and/or pelvic ultrasound, to help identify any structural issues that may be contributing to irregular cycles. For example, uterine fibroids or polyps can cause heavy bleeding and irregular periods;
• CT scans, to confirm suspicion of adnexal or adrenal masses;
• MRI for the pituitary gland, to confirm prolactinoma if prolactin levels are elevated;
• Endocervical swabs, to manage signs and symptoms of pelvic inflammatory disease.

In Summary

Overall, there is a range of lab tests that your healthcare provider may recommend if you are experiencing irregular cycles. It is important to work closely with your provider to determine which labs are most appropriate for your individual situation. With the right diagnosis and support, it is possible to manage irregular menstrual cycles, have a better sense of how to take care of yourself and improve your overall health and well-being.