Why Is Your Period Irregular? Key Hormone Tests for Women Explained
Explore the common causes of irregular periods and discover the essential hormone tests every woman should know to better understand her reproductive health and hormonal balance.
Written by Dr. Rohinipriyanka Pondugula
Reviewed by Dr. Md Yusuf Shareef MBBS
Last updated on 7th Aug, 2025
Irregular periods are common and can happen for many reasons. Stress, diet, weight changes, and exercise habits can all affect your cycle. However, in many cases, the root cause is a hormone imbalance. Hormones control your menstrual cycle. If even one of them is out of balance, your period may change.
Figuring out which hormone is out of balance may feel overwhelming, but it is an important part of understanding the cause and finding the right treatment. This article aims to simplify the role of key hormone tests for women, helping you understand the potential causes of irregular periods and how diagnostic insights can lead to clearer answers and personalised care.
Understanding Irregular Periods
A typical menstrual cycle lasts between 21 and 35 days, with bleeding that usually continues for 2 to 7 days. When your cycle regularly falls outside this pattern, it’s considered irregular.
Irregular periods can show up in different ways, such as:
- Cycles that are consistently shorter or longer than usual
- Very heavy or very light bleeding
- Skipped periods or no periods at all (a condition called amenorrhea)
- Periods that arrive at unpredictable times
Changes like these can affect more than just your physical health. They may impact your energy levels, mood, fertility, and overall quality of life. Often, irregular periods are a sign that your hormones are not in balance and that your body may need help restoring that balance.
Why Your Period Might Be Irregular: Here's What You Should Know
Your menstrual cycle is guided by a delicate hormonal system. When one or more of those hormones shifts out of range, or if the glands responsible for producing them aren’t working properly, it can affect how often your period shows up or how long it lasts. Here are some of the most common reasons why periods may become irregular:
Polycystic Ovary Syndrome (PCOS): PCOS affects a lot of women during their reproductive years. It can lead to irregular or skipped periods, higher levels of hormones like testosterone, and in some cases, tiny cysts on the ovaries. These hormonal shifts can make it harder to ovulate regularly, which can impact fertility too.
Thyroid Disorders: The thyroid helps control how your body uses energy and keeps your hormones balanced. Both an overactive (hyperthyroidism) and an underactive (hypothyroidism) thyroid can affect menstrual cycles, leading to irregular or missed periods.
- High Prolactin Levels (Hyperprolactinemia): Prolactin is the hormone primarily responsible for breast milk production. However, when you are not pregnant or breastfeeding, a high level of prolactin can disrupt ovulation and cause irregular or missed periods.
- Chronic Stress: Long-term physical or emotional stress can affect the hypothalamus, the part of the brain that controls the hormones involved in your cycle. This can lead to delayed or missed periods.
- Significant Weight Changes: Being underweight, overweight, or experiencing rapid changes in weight can interfere with normal hormone production and affect your cycle.
- Perimenopause: In the years leading up to menopause, usually between the late 30s and 50s, hormone levels begin to shift. This transition phase, called perimenopause, often causes irregular periods before they eventually stop altogether.
- Primary Ovarian Insufficiency (POI): Sometimes, the ovaries stop working properly before the age of 40. This condition, also known as early ovarian failure, can lead to irregular periods and symptoms similar to menopause.
What Hormone Tests Reveal About Irregular Periods
When periods become irregular, it's often a signal that something’s off with your hormones. To get to the root cause, doctors may recommend a set of blood tests that check your hormone levels. These tests can offer powerful insights into your reproductive health and guide the right treatment.
Here are some of the most important ones:
- Follicle-Stimulating Hormone (FSH) & Luteinizing Hormone (LH): Produced by the pituitary gland, these hormones help regulate ovulation and egg production. A high LH to FSH ratio can be a sign of Polycystic Ovary Syndrome (PCOS), a common cause of irregular cycles.
- Prolactin: This hormone supports breast milk production. When levels are abnormally high in those not pregnant or breastfeeding, prolactin can interfere with ovulation and lead to missed or irregular periods.
- Thyroid Hormones (TSH, T3, T4): These tests check how well your thyroid gland is working. Both an underactive and overactive thyroid can disrupt hormonal balance and throw off your menstrual cycle.
- Testosterone & DHEAS (Dehydroepiandrosterone Sulfate): Though called “male” hormones, women produce them in smaller amounts. Elevated levels may signal PCOS or problems with the adrenal glands, often causing symptoms like acne, excess body hair, and irregular periods.
- Estradiol (E2): The primary form of estrogen, estradiol, helps regulate your cycle. Low or high levels, especially outside normal fluctuations, can affect ovulation and the regularity of your periods.
How Hormone Tests Offer Clarity
These hormone tests for women are more than just numbers; they are diagnostic tools that help your doctor:
- Pinpoint the Root Cause: By analysing the levels and ratios of different hormones, your doctor can identify which specific hormonal pathways are disrupted.
- Differentiate Conditions: For instance, a high LH: FSH ratio combined with elevated testosterone might strongly suggest PCOS, while an abnormal TSH level would point to a thyroid issue.
- Guide Treatment: Once the underlying cause is identified, your doctor can recommend targeted treatments, which might include lifestyle modifications, medication, or other interventions to restore hormonal balance and regulate your cycle.
- Address Associated Concerns: Understanding the hormonal picture can also help address other symptoms you might be experiencing alongside irregular periods, such as weight changes, mood swings, or fertility challenges.
Simple and Reliable Hormone Testing with Apollo 24|7
Tracking your hormones can make a big difference when you're dealing with irregular periods or want to better understand your reproductive health. Apollo 24|7 makes testing simple and stress-free. Whether you need one test or a panel of hormone test for women, they offer options tailored to your personal health needs. It's clear, convenient, and easy to access.
Here are some important tests and packages they offer:
- FSH, LH, and Prolactin Tests: These assess how well your pituitary gland and ovaries are functioning.
- Thyroid Profile (T3, T4, TSH): A complete check of thyroid health, which can influence your menstrual cycle.
- Testosterone Test (Total) and Dihydro Testosterone(DHT): These androgens, found in smaller amounts in women, can be elevated in conditions like PCOS or adrenal disorders. Symptoms may include acne, excess hair growth, and irregular periods.
- Estradiol (E2) Test : As the primary form of estrogen, estradiol helps regulate the menstrual cycle. Abnormal levels can indicate hormonal imbalance and affect ovulation.
- AMH Test (Anti-Müllerian Hormone): Evaluates ovarian reserve and may help in diagnosing PCOS.
Apollo 24|7 also offers convenient hormone panels, like the Apollo PCOD Profile, which includes a range of hormone tests designed to help identify and manage Polycystic Ovary Syndrome, one of the most common causes of irregular periods.
Get Your Health Assessed Here
Member priceConclusion
Irregular periods can be a sign that your body’s hormonal balance is off. This is actually quite common, and it’s often your body’s way of telling you something needs attention. Instead of ignoring these changes, getting a thorough hormone test for women can help you understand causes of irregular periods. Choosing to check your hormones with a trusted service like Apollo 24|7 is a smart move toward better health. It gives you and your doctor the insights you need to find the right treatment. Taking control like this can help get your hormones back on track, make your periods more regular, and boost your overall well-being. Be sure to talk openly with your doctor about these tests and what they might mean for your health.
