Advanced Female Hormone Blood Test

Follicle Stimulating Hormone (FSH) is produced by your pituitary gland and stimulates the ovaries to develop follicles containing eggs. In the first half of the menstrual cycle, FSH levels rise to promote follicle growth; one follicle becomes dominant and is released at ovulation, after which FSH levels drop. FSH levels vary throughout the cycle—they're lowest mid-cycle and highest just before and during menstruation. As women approach menopause and ovarian reserve declines, FSH levels rise as the pituitary works harder to stimulate the ovaries. Persistently elevated FSH (above 25-30 IU/L) with menopausal symptoms supports a diagnosis of menopause. For cycle assessment, FSH is best measured on days 2-5. Hormonal contraception suppresses FSH. Results outside the normal range may need a follow-up with your GP.

Luteinising Hormone (LH) is produced by your pituitary gland and triggers ovulation—the mid-cycle LH surge causes the dominant follicle to release its egg. After ovulation, LH supports the corpus luteum, which produces progesterone. Like FSH, LH levels vary throughout the cycle and rise significantly around menopause. The ratio of LH to FSH can provide diagnostic clues—an elevated LH: FSH ratio (above 2:1 or 3:1) is sometimes seen in polycystic ovary syndrome (PCOS), though this pattern alone isn't required for diagnosis. For cycle assessment, LH is best measured on days 2-5. Hormonal contraception affects LH levels. Results outside the normal range may need a follow-up with your GP.

Oestradiol is the primary and most potent form of oestrogen, produced mainly by the ovaries. It's responsible for developing and maintaining female reproductive tissues, regulating the menstrual cycle, and supporting bone density, skin health, and cardiovascular function. Oestradiol levels fluctuate dramatically throughout the menstrual cycle—lowest during menstruation, rising through the follicular phase, peaking just before ovulation, then rising again in the luteal phase. After menopause, oestradiol falls to very low levels (typically below 100 pmol/L), contributing to symptoms like hot flushes, vaginal dryness, and increased bone loss risk. For cycle or menopausal assessment, oestradiol is best measured on days 2-5. Hormonal contraception provides synthetic oestrogen and suppresses natural production. Results outside the normal range may need a follow-up with your GP.

Testosterone is primarily known as a male hormone but is also produced in smaller amounts by women's ovaries and adrenal glands. In women, testosterone plays important roles in libido, energy, mood, muscle and bone strength, and cognitive function. Testosterone levels in women are much lower than in men but remain important for wellbeing. Elevated testosterone in women can contribute to symptoms like acne, excess facial or body hair (hirsutism), hair thinning on the scalp, and irregular periods—symptoms often associated with polycystic ovary syndrome (PCOS). Low testosterone in women can cause reduced libido, fatigue, and low mood. Testosterone is interpreted alongside SHBG and the calculated free androgen index (FAI) for a complete picture. Results outside the normal range may need a follow-up with your GP.

The Free Androgen Index (FAI) is a calculation that estimates how much testosterone is 'free' and biologically active, rather than bound to proteins like SHBG. It's calculated from the ratio of total testosterone to SHBG. Most testosterone in blood is bound to SHBG and is inactive—only the free portion can interact with your body's cells. In women, the FAI is particularly useful for assessing androgenic symptoms and is a key marker when investigating polycystic ovary syndrome (PCOS). An elevated FAI—even with normal total testosterone—suggests excess androgen activity and can help explain symptoms like acne, hirsutism, or menstrual irregularity. The FAI provides more clinical insight than total testosterone alone in women. Results outside the normal range may need a follow-up with your GP.

Prolactin is a hormone produced by your pituitary gland, primarily known for stimulating breast milk production after childbirth. During pregnancy and breastfeeding, prolactin levels are naturally elevated. Outside of pregnancy and breastfeeding, elevated prolactin (hyperprolactinaemia) can cause menstrual irregularities, reduced fertility, and sometimes inappropriate breast milk production (galactorrhoea). High prolactin suppresses the release of FSH and LH, which disrupts ovulation. Causes of elevated prolactin include pituitary tumours (usually benign prolactinomas), certain medications (particularly some antipsychotics and antidepressants), hypothyroidism, and stress. Prolactin levels are highest during sleep and fall after waking, which is why morning testing is important. Stress, exercise, nipple stimulation, and heavy meals can all temporarily raise prolactin. Results outside the normal range may need a follow-up with your GP.

Sex Hormone Binding Globulin (SHBG) is a protein made by your liver that transports sex hormones (testosterone, oestrogen, and DHT) in your blood. Hormones bound to SHBG are inactive—they can't interact with your body's cells. Only 'free' (unbound) hormones are biologically active. SHBG levels affect how much hormone is available to your tissues. Low SHBG means more free testosterone, which can contribute to androgenic symptoms like acne and hirsutism even when total testosterone is normal—this pattern is commonly seen in PCOS. High SHBG means less free hormone is available. SHBG is affected by many factors: it's increased by oestrogen (including the contraceptive pill), hyperthyroidism, liver disease, and ageing; it's decreased by insulin resistance, obesity, hypothyroidism, and excess androgens. SHBG is used alongside testosterone to calculate the free androgen index. Results outside the normal range may need a follow-up with your GP.

TSH is produced by your pituitary gland to regulate thyroid hormone production. It works in a feedback loop—when thyroid hormones are low, TSH rises to stimulate more production; when thyroid hormones are high, TSH drops. This makes TSH the most sensitive marker for thyroid dysfunction. High TSH indicates hypothyroidism (underactive thyroid)—symptoms include fatigue, weight gain, cold intolerance, constipation, low mood, and menstrual irregularities. Low TSH indicates hyperthyroidism (overactive thyroid)—symptoms include anxiety, weight loss, tremor, heat intolerance, and light or absent periods. Thyroid problems are much more common in women than men, and thyroid conditions can significantly affect fertility and menstrual regularity. Hypothyroidism can cause heavy, prolonged periods; hyperthyroidism can cause light or absent periods. Results outside the normal range may need a follow-up with your GP.

Free T3 is the active form of thyroid hormone—it's the hormone that actually works in your cells to regulate metabolism, energy production, and many other functions. Most T3 is produced by conversion from T4 in your tissues rather than directly by the thyroid. Free T3 measures the unbound, active portion. Some people have difficulty converting T4 to T3, which can cause persistent hypothyroid symptoms despite normal TSH and T4. Low T3 can also occur during illness (sick euthyroid syndrome), with extreme calorie restriction, or with high stress. Free T3 helps complete the picture of thyroid function, particularly when symptoms persist despite treatment or when TSH and T4 don't fully explain symptoms. Results outside the normal range may need a follow-up with your GP.

Free T4 is the unbound, active portion of thyroxine—the main hormone your thyroid produces. T4 circulates in blood and is converted to the more active T3 in tissues as needed. Measuring Free T4 alongside TSH confirms and characterises thyroid dysfunction. High TSH with low Free T4 confirms overt hypothyroidism—the thyroid isn't producing enough hormone. High TSH with normal Free T4 is subclinical hypothyroidism—the thyroid is struggling but managing to maintain adequate hormone output. Low TSH with high Free T4 confirms hyperthyroidism—the thyroid is overactive. Free T4 is also used to monitor thyroid hormone replacement (levothyroxine) therapy. Thyroid function during pregnancy has particular importance as thyroid hormones are essential for foetal brain development. Results outside the normal range may need a follow-up with your GP.

Thyroglobulin antibodies are proteins produced by your immune system that target thyroglobulin, a protein specific to the thyroid gland used in thyroid hormone production. Under normal circumstances, thyroglobulin doesn't enter the bloodstream in significant amounts. When the thyroid is inflamed or under autoimmune attack, thyroglobulin can be released and the immune system may produce antibodies against it. Elevated thyroglobulin antibodies indicate autoimmune thyroid disease—either Hashimoto's thyroiditis (which causes hypothyroidism) or Graves' disease (which causes hyperthyroidism). Autoimmune thyroid disease is much more common in women than men. Importantly, elevated thyroid antibodies are associated with an increased risk of miscarriage and pregnancy complications, even when thyroid hormone levels are normal. Results outside the normal range may need a follow-up with your GP.

Thyroid peroxidase (TPO) is an enzyme essential for producing thyroid hormones. TPO antibodies are produced when the immune system mistakenly attacks this enzyme. Elevated TPO antibodies are the most common marker of autoimmune thyroid disease and are found in the majority of people with Hashimoto's thyroiditis and many with Graves' disease. Some people have elevated TPO antibodies but normal thyroid function—they're at increased risk of developing thyroid problems in the future and should have periodic monitoring. Like thyroglobulin antibodies, elevated TPO antibodies are associated with increased miscarriage risk even with normal thyroid hormone levels. Autoimmune thyroid disease often runs in families and is much more common in women. Testing for thyroid antibodies helps identify autoimmune causes of thyroid dysfunction and can flag increased pregnancy risk. Results outside the normal range may need a follow-up with your GP.