LH levels in blood: normal ranges by cycle phase, LH/FSH ratio, and LH in men

Your lab report shows an LH level, next to it a reference range, perhaps flagged with an asterisk. Or your doctor tested LH together with FSH and calculated a ratio. What does this number tell you?

Less than you might think, as long as nobody notes on which cycle day the blood was drawn. LH, the luteinizing hormone, varies many times over during the cycle, is released in pulses, and is evaluated against different reference ranges depending on the lab and the measurement method. A value that counts as elevated in one lab can still be within the range in another.

Here you will find the reference ranges of large laboratories as a table, the right time for the measurement, what high and low values can mean, what the LH/FSH ratio shows, and what matters in men. None of this can interpret your own results. That belongs in a conversation with your doctor, together with your cycle, symptoms, and your other hormone levels.

What is LH?

LH stands for luteinizing hormone. It is produced in the anterior lobe of the pituitary gland and, together with follicle-stimulating hormone (FSH), regulated by the control hormone GnRH from the hypothalamus (Medicover 2026).

• In women, LH triggers ovulation and then keeps the corpus luteum functioning. What happens in this second half of the cycle is explained in the article on luteal phase defect.
• In men, LH stimulates the Leydig cells in the testicles to produce testosterone and thereby contributes to the regulation of sperm production (Medicover 2026).

LH does not flow into the blood evenly but in pulses, because GnRH, too, is released in bursts. Pulse frequency and pulse amplitude change with the cycle phase: In the follicular phase, there is a pulse about every 90 minutes, in the luteal phase only every 3 to 6 hours (Endokrinologikum Hamburg). FSH has a longer half-life, so the pulses show up mainly in LH. A single LH value fluctuates more than a single FSH value (Ulm University Hospital 2024).

For you, that means an LH level is a snapshot. It shows the state at the time of the blood draw, not your cycle as a whole.

LH levels chart: reference ranges by cycle phase

The table shows the reference ranges of three German laboratories. They are examples, not universally valid normal values. Ulm University Hospital, which measures with the Roche Elecsys test (ECLIA method), explicitly describes its values as indicative only and as dependent on age and sex (Ulm University Hospital 2024).

All values in IU/l. Sources: Ulm University Hospital (revision of January 2024), Medicover Diagnostics (as of August 2026), central laboratory of Hannover Medical School (MHH) (version 7.0, June 2025).

Units: 1 IU/l equals 1,000 mIU per 1,000 ml, that is, 1 mIU/ml. On lab reports, the same thing is also printed as mIE/ml or U/l: Endokrinologikum Hamburg gives the same Roche ranges in mIE/ml, Ulm University Hospital in IU/l, and the MHH in U/l. A value of 7 IU/l and one of 7 mIU/ml are therefore equally high.

The table is not a tool for classifying your own value. Whether a result is abnormal depends on the cycle day, accompanying values, and your history. Your doctor makes that assessment.

Why there is no single normal LH range

The three examples already show it: For men, the upper limit at Medicover is about 3.5 IU/l higher than for the Roche test, and at the MHH it is 14.0 instead of 8.6. Reference ranges depend on the measurement method and the laboratory; what counts is always the range on your own lab report (Medicover 2026, MHH 2025). Other factors come on top of that:

• The cycle day: The same value can be above the reference range in the follicular phase and right in the middle of it around ovulation. For example, 20 IU/l is above the follicular-phase range for the Roche test but within the ovulation-phase range.
• The pulses: A value reflects the moment of the blood draw, not a daily average.
• The pill and GnRH analogs: They suppress the axis of hypothalamus, pituitary gland, and ovaries and thereby also block the production and release of LH. A value measured while on the pill shows the effect of the medication, not your own cycle function (Endokrinologikum Hamburg).
• Biotin: With the Roche test, high-dose biotin can distort the result. If you take more than 5 mg of biotin a day, blood should be drawn no earlier than 8 hours after the last dose (Endokrinologikum Hamburg). According to Ulm University Hospital, biotin concentrations below 50 ng/ml do not affect the test. Medicover, which measures with a different method, does not list biotin among its interfering factors. If you take high-dose biotin, say so before the blood draw and clarify the interval since your last dose with the lab.
• Antibodies in the blood: Human anti-mouse antibodies (HAMA), for example after treatment with monoclonal antibodies from mice, and so-called heterophilic antibodies can interfere with the measurement. The result then comes out falsely high or falsely low (Medicover 2026).

When is the LH level measured?

When blood is drawn depends on the question that needs to be answered.

The DACH guideline from the German, Austrian, and Swiss societies DGGG, OEGGG, and SGGG (2026) names cycle day 2 to 5 for the baseline values. The laboratories name slightly different days; what they all have in common is the early follicular phase. The British guideline NICE NG257 (2026) recommends offering women with an irregular cycle a blood test for FSH and LH. Which other tests belong in the work-up for infertility and what they cost is covered in the article Fertility test for women.

If you take the pill: On the pill, an LH level says little about your own cycle (Endokrinologikum Hamburg). For PCOS diagnostics, the international guideline advises: If male hormones absolutely must be measured, the pill should be stopped at least 3 months beforehand and another form of contraception used (international PCOS guideline 2023). Whether and when you stop is something you discuss with your doctor.

LH peak: the surge before ovulation

Before ovulation, LH rises steeply until it reaches its high point, the LH peak. A study commissioned by the WHO investigated how much time passes after that until ovulation. LH was measured in the blood, and ovulation was confirmed surgically. A total of 177 women were studied, and 107 of them were included in the analysis (WHO 1980).

Source: WHO Task Force on Methods for the Determination of the Fertile Period (1980).

Then there is the spread. According to the study’s statistical model, ovulation occurred in 90% of cases between 16 and 48 hours after the first clear LH rise in the blood, each with an uncertainty of plus or minus 6 hours. Relative to the peak, it occurred between 3 hours before and 36 hours after, each plus or minus 5 hours (WHO 1980).

How high LH rises around ovulation varies a great deal: The reference range for the ovulation phase runs from 14.0 to 95.6 IU/l for the Roche test and from 7.59 to 89.08 IU/l for Medicover (Ulm University Hospital 2024, Medicover 2026). At home, the rise can be detected in urine.

LH blood test or LH urine test?

Ovulation tests from the drugstore or pharmacy also measure LH, but differently from the lab.

Sources: FDA (2018), Endokrinologikum Hamburg, Ulm University Hospital (2024).

What professional societies and agencies state about urine tests:

• Urine results usually agree well with the peak in the blood, especially with midday or evening urine (ASRM 2021).
• After a rise detected in urine, ovulation can occur at any point within the following 2 days. In about 7% of cycles, the result is false positive (ASRM 2022).
• Used correctly, urine tests detect the rise in about 9 out of 10 cases, according to the FDA. What is detected is the LH surge, not ovulation itself. The tests are not suitable for contraception (FDA 2018).
• Accuracy, handling, and reliability differ by product. False positive and false negative results occur (ASRM 2021).
• In PCOS, a persistently elevated baseline LH can lead to false positive urine tests (ASRM 2021).

How to use ovulation tests, from which cycle day and at what time of day, is explained in the article on the ovulation test. A urine test does not provide a blood value that you can compare with your lab’s reference ranges.

High LH levels: possible causes

A high LH level on its own is not a diagnosis. Around ovulation, a high value is even to be expected, as the reference range for the ovulation phase shows. LH becomes meaningful only together with the cycle day, with FSH, and with other values. Laboratories and guidelines mainly describe these patterns:

Premature ovarian insufficiency: FSH decides, not LH

When the ovaries lose their function before age 40, experts speak of premature ovarian insufficiency (POI). For the diagnosis, the guideline from ESHRE and ASRM requires at least 4 months of disturbed cycles and an FSH above 25 IU/l. The test is repeated after 4 to 6 weeks only if the diagnosis is uncertain. LH is not one of the diagnostic criteria (ESHRE 2024).

Hormonal contraception with the pill, injection, or long-acting contraception can mask or cause cycle disorders and lower FSH levels. The guideline therefore advises stopping some products before a POI diagnosis (ESHRE 2024).

High LH in PCOS

The German S2k guideline describes a frequently disturbed release of the control hormones in PCOS, with increased LH secretion (AWMF 089-004, 2025). An elevated LH is therefore typical. It is still not one of the diagnostic criteria; more on this in the section on the LH/FSH ratio.

Low LH levels: possible causes

Even a low value can be within the reference range: In the luteal phase, the range goes down to 1.0 IU/l for the Roche test and to 0.56 IU/l for Medicover (Ulm University Hospital 2024, Medicover 2026). Laboratories and guidelines name these reasons for low values:

• The pill and GnRH analogs: They suppress LH, so the value then shows the effect of the medication (Endokrinologikum Hamburg). How hormones are deliberately controlled in fertility treatment is explained in the article on hormone treatment for fertility.
• A cause in the hypothalamus or pituitary gland: Low to undetectable LH levels together with low FSH and low estrogen are found when periods stop because of a disorder in these control centers. Anorexia nervosa, marked underweight, injuries to the pituitary stalk, and other damage to the pituitary gland are named in particular (Endokrinologikum Hamburg).
• Elevated prolactin: In women, hyperprolactinemia typically shows up as milk discharge from the breast and centrally caused hypogonadism with cycle disorders up to absent periods (Wisplinghoff Laboratory). In men, elevated prolactin suppresses LH and FSH (EAU 2026).
• Anabolic steroids: Anabolic-androgenic steroids suppress the release of LH and FSH. In women, this can lead to cycle disorders and infertility (Endocrine Society 2014).

Functional hypothalamic amenorrhea: LH often in the normal range

If ovulation stays absent for a long time without an organic cause being found, functional hypothalamic amenorrhea (FHA) may be behind it. According to the Endocrine Society guideline, it is often triggered by stress, weight loss, excessive exercise, or a combination of these. It is diagnosed only once other causes have been ruled out (Endocrine Society 2017).

For the lab values, this means: According to ASRM, LH and FSH are in the normal to low-normal range in FHA. A normal LH or FSH value therefore does not rule out FHA (ASRM 2024).

In a cohort from Vienna of 135 women with confirmed FHA, only 39% had an LH of at most 2.0 mIU/ml and 13% had an FSH of at most 2.0 mIU/ml. A low ratio was more typical: 81.5% had an LH/FSH ratio of at most 1.0, and only 2.2% had one of 2.1 or more (Medical University of Vienna 2024).

The GnRH test

To narrow down a disorder in the hypothalamus or pituitary gland more precisely, there is the GnRH stimulation test, also called the LH-RH test. It measures how LH and FSH respond to GnRH. In women, LH normally rises 2- to 8-fold, FSH less strongly. A reduced or absent rise points to a disorder in the hypothalamus or pituitary gland (Augsburg Laboratory).

The early follicular phase is ideal, that is, cycle day 2 to 5. Depending on how long they act, hormonal contraceptives should be stopped at least one regular cycle beforehand, or 8 weeks if periods are absent (Augsburg Laboratory).

LH/FSH ratio: what it shows and what it does not

To calculate the LH/FSH ratio, the LH value is divided by the FSH value. In healthy women of reproductive age, it is around 1, according to the central laboratory of the MHH (MHH 2025).

A high LH with normal FSH is often found when ovulation is chronically absent, especially in PCOS. It is typical, but not conclusive (Endokrinologikum Hamburg).

What the PCOS guidelines say

The international evidence-based PCOS guideline from 2023 requires 2 of 3 criteria for the diagnosis:

1. an excess of male hormones, recognizable from signs on the body or measured in the blood (hyperandrogenism),
2. a disturbed ovulation (ovulatory dysfunction),
3. polycystic ovaries on ultrasound or, alternatively, an elevated AMH.

In addition, other causes must be ruled out. LH and the LH/FSH ratio are not among the criteria (international PCOS guideline 2023). The German S2k guideline also makes the diagnosis according to the modified Rotterdam criteria, adopted with 100% consensus. Here, too, LH and the ratio are not a diagnostic criterion (AWMF 089-004, 2025, recommendation 1.2.1). How AMH values are distributed by age in studies is shown in the AMH Chart.

What LH is then measured for: to rule out other causes. In the diagnostic algorithm of the international guideline, FSH, together with TSH, prolactin, and 17-OH progesterone, is one of the standard tests for ruling out other causes. LH and FSH also serve to rule out hypogonadotropic hypogonadism, that is, a deficiency of control hormones from the pituitary gland. It is usually caused by a low body fat percentage or intensive training (international PCOS guideline 2023).

The German guideline measures LH, FSH, and estradiol to distinguish PCOS from, among other things, hypothalamic amenorrhea (including functional amenorrhea, for example in anorexia nervosa, exercise, or stress) or an underactive pituitary gland (AWMF 089-004, 2025).

Since May 2026, PCOS has been called PMOS internationally, polyendocrine metabolic ovarian syndrome (Lancet 2026). ASRM already uses the new name, and the DACH guideline (2026) uses the abbreviation PMOS. A transition period applies. There is no newer version of the international guideline so far, and the 2023 criteria remain in force. We use PCOS here because most people search for that term. How treatment works when you are trying to conceive is described in the article Getting pregnant with PCOS.

What studies on the ratio show

In a small study, blood was drawn 10 times over a full cycle from each of 12 women with PCOS and 11 women without PCOS. The median LH/FSH ratio did not differ significantly: 1.6 versus 1.2 (p = 0.14). Only 7.6% of the samples from women with PCOS were above 3, but 15.6% of the samples from healthy women were. The authors conclude that the ratio is of little use for diagnosing PCOS (Cho 2006).

The ratio can be helpful for a different question: PCOS or FHA? In FHA, according to ASRM, LH is often disproportionately lower than FSH, whereas in PCOS an LH that is elevated relative to FSH is not unusual (ASRM 2024). This matters because up to 50% of women with FHA show polycystic ovaries with elevated AMH on ultrasound and are therefore easily misclassified as having PCOS (Medical University of Vienna 2024). For this differentiation, the ratio can help; it does not replace the diagnostic criteria (ASRM 2024).

LH levels in men

In men, LH is the signal to the testicles to produce testosterone. The Leydig cells respond to it, and LH thereby contributes to the regulation of sperm production (Medicover 2026).

The reference ranges differ widely here, too: 1.7 to 8.6 IU/l for the Roche test (Ulm University Hospital 2024), 0.57 to 12.07 IU/l for Medicover (Medicover 2026), and 1.5 to 14.0 IU/l at the MHH (MHH 2025).

The DACH guideline (2026) calls for FSH, LH, and testosterone as the baseline hormone tests in men. LH becomes meaningful only in the interplay of these three values:

Klinefelter syndrome

The most common genetic cause of primary hypogonadism with elevated LH is Klinefelter syndrome with the karyotype 47,XXY. It affects 1 in 500 to 1,000 live-born boys. Fewer than half of those affected are diagnosed during their lifetime (EAU 2026).

Elevated prolactin

An elevated prolactin level suppresses LH and FSH and thus leads to reduced fertility. According to the EAU guideline, treatment is given regardless of the cause, including in the case of a pituitary adenoma, with a dopamine agonist or by stopping the medication that is causing it (EAU 2026).

Testosterone and anabolic steroids

Testosterone from outside the body, even as a medically prescribed therapy, slows the release of LH and FSH by the pituitary gland. As a result, sperm production and sperm maturation deteriorate. Testosterone therapy is therefore contraindicated when you are trying to conceive (EAU 2026).

Anabolic steroids work on the same principle: Anabolic-androgenic steroids suppress LH and FSH, which in men can suppress sperm production and lead to infertility (Endocrine Society 2014). If anabolic steroids have left only very few sperm or none at all in the ejaculate, the first step is to stop them. Sperm count and sperm quality usually recover within 6 to 12 months. This figure is based on case reports and clinical experience (EAU 2026).

Which tests are part of the work-up in men, from the semen analysis to the hormones, is explained in the article Male fertility test. Causes and treatments are described in the guide Male infertility.

What you can do with your lab results

No chart on the internet can interpret your results, including this one. For the conversation with your doctor, a few details that you can write down beforehand will help:

• On which cycle day was the blood drawn, and when did your next period come?
• Did you use hormonal contraception or take other hormones in the weeks before?
• Are you taking high-dose biotin?
• Were FSH and other hormones measured at the same blood draw?
• Do you have symptoms such as an irregular cycle, absent periods, or milk discharge from the breast?

When an evaluation of both partners makes sense is described in the guide to infertility. You can find clinics near you in the clinic directory.

Frequently asked questions

What is a normal LH level?

It depends on the cycle phase and the laboratory. For the Roche test, the ranges are 2.4 to 12.6 IU/l in the follicular phase, 14.0 to 95.6 IU/l around ovulation, 1.0 to 11.4 IU/l in the luteal phase, and 7.7 to 58.5 IU/l after menopause (Ulm University Hospital 2024). Other laboratories give other ranges; what counts is the range on your lab report.

When is an LH level too high?

Around ovulation, a high value is normal. If LH and FSH are elevated at the same time, this can occur in the menopausal transition, after menopause, or in premature ovarian insufficiency. A high LH with normal FSH is often found in PCOS but is not conclusive (Endokrinologikum Hamburg).

What does a low LH level mean?

A low value can be within the reference range; in the luteal phase, it goes down to 1.0 IU/l for the Roche test. On the pill, LH is suppressed. Low LH together with low FSH and estrogen can point to a cause in the hypothalamus or pituitary gland, for example in anorexia nervosa or marked underweight. Conversely, a normal value does not rule out functional hypothalamic amenorrhea (Endokrinologikum Hamburg, ASRM 2024).

What does the LH/FSH ratio tell you?

In healthy women, it is around 1 (MHH 2025). A high ratio is often found in PCOS but, according to the international and German guidelines, is not one of the diagnostic criteria. It can be helpful for distinguishing PCOS from functional hypothalamic amenorrhea, in which it is usually at most 1.0 (ASRM 2024, Medical University of Vienna 2024).

How high is the LH peak, and when does ovulation follow?

How high LH rises around ovulation varies widely: For the Roche test, the reference range for the ovulation phase runs from 14.0 to 95.6 IU/l (Ulm University Hospital 2024). In the WHO study, ovulation followed the LH peak by a median of 16.5 hours and the start of the rise by 32.0 hours (WHO 1980).

What is a normal LH level in men?

For the Roche test, 1.7 to 8.6 IU/l; for Medicover, 0.57 to 12.07 IU/l; at the MHH, 1.5 to 14.0 IU/l. High LH and FSH with low testosterone point to damage in the testicles, and low LH and FSH with low testosterone to a cause in the hypothalamus or pituitary gland (Endokrinologikum Hamburg). Testosterone from outside the body and anabolic steroids suppress LH (EAU 2026, Endocrine Society 2014).

Can an ovulation test measure my LH level?

Not in the way a lab does. Test strips and most digital ovulation tests are qualitative tests: They show only whether LH is elevated, not how high, and also not whether a pregnancy will occur (FDA 2018). Some hormone monitors do display a number for LH in urine. However, this urine value cannot be compared with the blood value and the reference ranges on your lab report. In PCOS, a persistently elevated LH can lead to false positive tests (ASRM 2021).

Does the pill change the LH level?

Yes. The pill suppresses the control axis of the hypothalamus, pituitary gland, and ovaries, and with it LH. A value measured on the pill shows the effect of the medication, not your own cycle function (Endokrinologikum Hamburg). For a GnRH test, hormonal contraception should be stopped at least one regular cycle beforehand, depending on how long it acts (Augsburg Laboratory).

Sources

Guidelines and statements

• Diagnostics and therapy before medically assisted reproduction treatment, S2k guideline AWMF 015-085, version 2.0, DGGG, OEGGG, and SGGG, 2026
• Teede HJ et al.: Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome, Hum Reprod 2023;38(9):1655-1679, Monash University with ESHRE, ASRM, Endocrine Society, and ESE, 2023
• Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of PCOS, Algorithm 1 (Diagnostic algorithm), ASRM version, 2023
• Teede HJ et al.: Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process, Lancet 2026;407(10545):2329-2339
• S2k guideline Diagnostics and therapy of polycystic ovary syndrome (PCOS), long version, AWMF 089-004, German Society for Endocrinology et al., version of August 2025
• Evidence-based guideline: premature ovarian insufficiency, Hum Reprod Open 2024;2024(4):hoae065, ESHRE, ASRM, CRE-WHiRL, and IMS Guideline Group on POI, 2024
• Current evaluation of amenorrhea: a committee opinion, Fertil Steril 2024;122:52-61, ASRM Practice Committee, 2024
• Fertility evaluation of infertile women: a committee opinion, Fertil Steril 2021;116:1255-1265, ASRM Practice Committee, 2021 (online version)
• Optimizing natural fertility: a committee opinion, Fertil Steril 2022;117:53-63, ASRM Practice Committee and SREI, 2022
• Gordon CM et al.: Functional Hypothalamic Amenorrhea: An Endocrine Society Clinical Practice Guideline, J Clin Endocrinol Metab 2017;102(5):1413-1439, Endocrine Society with ASRM, ESE, and PES, 2017
• Pope HG Jr et al.: Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement, Endocr Rev 2014;35(3):341-375, Endocrine Society, 2014
• EAU Guidelines on Sexual and Reproductive Health, chapter Male Infertility, European Association of Urology, 2026
• EAU Guidelines on Sexual and Reproductive Health, chapter Male Hypogonadism, European Association of Urology, 2026
• Fertility problems: assessment and treatment (NG257), Investigation of fertility problems and management strategies, NICE, March 31, 2026

Studies

• WHO Task Force on Methods for the Determination of the Fertile Period: Temporal relationships between ovulation and defined changes in the concentration of plasma estradiol-17 beta, luteinizing hormone, follicle-stimulating hormone, and progesterone. I. Probit analysis, Am J Obstet Gynecol 1980;138(4):383-390
• Cho LW et al.: The LH/FSH ratio has little use in diagnosing polycystic ovarian syndrome, Ann Clin Biochem 2006;43(Pt 3):217-219
• The LH:FSH Ratio in Functional Hypothalamic Amenorrhea: An Observational Study, J Clin Med 2024;13(5):1201, Medical University of Vienna, 2024

Laboratory test directories

• Test directory entry luteinizing hormone (FB-PAE 6 LH OE), Ulm University Hospital, Central Facility for Clinical Chemistry, Revision 003 of January 23, 2024
• Luteinizing hormone (LH), test directory laboratory medicine, Medicover Diagnostics (MVZ Martinsried), as of August 31, 2026
• Test directory ZLA reference ranges, version 7.0, Central Laboratory of Hannover Medical School, June 18, 2025
• Test directory luteinizing hormone, Endokrinologikum / Aesculabor Hamburg, retrieved October 4, 2026
• Services gynecology (androgenization, suspected PCOS, hyperprolactinemia), Dr. Wisplinghoff Laboratory, Cologne, retrieved October 4, 2026
• LH-RH test (function tests), Augsburg Laboratory (Labor Augsburg MVZ GmbH), retrieved October 4, 2026

Agencies

• Ovulation (Urine Test), Home Use Tests, U.S. Food and Drug Administration (FDA), 2018