Blood test
LH test
LH test: what it measures, why a doctor orders it, how to prepare, and what a high or low result can mean - with private and NHS access routes in the UK.
Key facts
At a glance
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What it measures: luteinising hormone, the pituitary hormone that triggers ovulation in women and drives testosterone production in men.
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Why it is ordered: in fertility assessment, suspected PCOS, absent or irregular periods, and to localise the cause of low testosterone in men.
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No fasting is needed; in menstruating women the sample is usually timed to days 2-5 of the cycle.
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Reference ranges: the LH to FSH relationship and the cycle day carry most of the interpretive weight. Every laboratory publishes its own interval, so the range printed on your report is the one that applies to you.
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A raised result relative to FSH is a common pattern in PCOS, and a mid-cycle surge is the normal ovulation trigger. A low result alongside low testosterone or oestradiol points to a pituitary or hypothalamic cause.
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Results are usually back within 24-48 hours when taken privately, and often the same day for urgent requests.
The full picture
What this test tells you, and how to get it
The LH test measures luteinising hormone, the pituitary hormone that triggers ovulation in women and drives testosterone production in men. Doctors most often request it in fertility assessment, suspected PCOS, absent or irregular periods, and to localise the cause of low testosterone in men. No fasting is needed; in menstruating women the sample is usually timed to days 2-5 of the cycle. The LH to FSH relationship and the cycle day carry most of the interpretive weight, and reference intervals genuinely differ between laboratories, so no single number should be treated as a universal cut-off - your result is always read against the range printed on your own report. Broadly, a raised result relative to FSH is a common pattern in PCOS, and a mid-cycle surge is the normal ovulation trigger, while a low result alongside low testosterone or oestradiol points to a pituitary or hypothalamic cause, and either finding is interpreted alongside your symptoms, medication and other results rather than in isolation. Results are usually back within 24-48 hours when taken privately, and often the same day for urgent requests.
In the UK there are two routes to this test. Your NHS GP can arrange it free of charge when it is clinically indicated, though getting the appointment, the blood draw and the follow-up discussion can add days to weeks depending on local demand. Privately, the LH test can usually be booked within days - through a private GP, a walk-in phlebotomy clinic or a self-request home-testing service - always paired with FSH. A private result still deserves a clinician's interpretation: an isolated number without context is where most confusion about blood tests begins.
A quiet reminder
This guide is for information, not medical advice.
Your own clinician knows your history and can tell you which parts apply to you. Reference ranges vary between laboratories - always read your result against the interval printed on your own report. Next review of this page: 2027-09-27.
Frequently asked
Common questions about LH test.
Quick, plain-English answers to what people ask us most.
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What is an LH test?
LH, or luteinising hormone, is produced by the pituitary gland and plays a key role in regulating the reproductive system in both men and women. This blood test measures how much LH is circulating at the time of the sample.
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Why would a doctor order an LH test?
It's commonly used to investigate fertility concerns, irregular periods, suspected menopause or perimenopause, or to help time ovulation when trying to conceive. In men, it can help assess testosterone production and pituitary or testicular function.
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Do I need to prepare for an LH test?
No fasting is usually required, but timing matters, as LH levels vary through the menstrual cycle, so your doctor may ask you to test on a specific cycle day. If you're not having periods or have an irregular cycle, let your clinician know so timing can be adjusted appropriately.
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What happens during the test?
It's a simple blood draw from a vein in your arm, taking only a few minutes to complete. No special equipment or recovery time is needed afterwards.
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Does an LH test hurt?
You'll feel a brief pinch as the needle goes in, similar to any standard blood test, with minimal ongoing discomfort. Most people find it very manageable.
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How long do LH test results take?
Private results are usually available within a few days, and your doctor will interpret them in the context of your cycle timing and symptoms. This context matters a great deal for LH, since a single number without timing information can be misleading.
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What do abnormal LH results mean, and what happens next?
Levels outside the expected range can relate to a variety of causes, including polycystic ovary syndrome, menopause, pituitary conditions, or hormonal imbalances affecting fertility. Your doctor will usually look at LH alongside other hormones like FSH and oestradiol before recommending any further tests or treatment.
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Is LH testing available on the NHS, and how much does private testing cost?
LH testing is available on the NHS, generally as part of a fertility or hormone work-up arranged through your GP, though waiting times for review can vary. Private testing is typically available within days with specialist interpretation included; cost varies by provider.
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Is the LH test accurate and reliable?
The laboratory measurement is reliable, but because LH fluctuates naturally through the menstrual cycle and day, accurate interpretation depends heavily on correct timing. This is why your doctor will usually want to know your cycle day or relevant clinical context.
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How do I book an LH test privately, and how quickly can I be seen?
Booking is straightforward online, with appointments often available within a day or two, including guidance on the best time in your cycle to test. A specialist can then talk you through what your results mean for your specific situation.