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LH levels through the menstrual cycle

Luteinizing hormone, from the pituitary gland, whose surge triggers ovulation. Below are the median and the 5th to 95th percentile for each day from 15 days before the LH peak to 14 after, in mIU/mL, which is the same number in IU/L.

What is a normal LH level around ovulation?

On the day of the LH peak, the median in Stricker and colleagues’ 20 women was 41.19 mIU/mL (41.19 IU/L), and the middle 90 percent ran from 21.16 to 73.63 mIU/mL. Ovulation follows the peak by a median 16.5 hours, found by a WHO task force that examined the ovaries of 107 women at surgery.

LH through the menstrual cycle, daily median and 5th to 95th percentile Line chart of the daily median LH in mIU/mL, with a band from the 5th to the 95th percentile, from day −15 to day +14 about the LH peak. The median peaks at 41.19 mIU/mL on day 0. Every value is in the table below. 020406080 −15−10−50+5+10+14 Days from the LH peak mIU/mL Follicular phaseLuteal phase LH peak Peak median 41.19 mIU/mL, day 0 Day −15: median 2.28 mIU/mL, 5th to 95th percentile 0.37 to 5.79 mIU/mL, 9 women Day −14: median 3.39 mIU/mL, 5th to 95th percentile 1.35 to 6.29 mIU/mL, 12 women Day −13 (day 1 of a 28-day cycle): median 3.47 mIU/mL, 5th to 95th percentile 2.35 to 7.36 mIU/mL, 15 women Day −12 (day 2 of a 28-day cycle): median 3.59 mIU/mL, 5th to 95th percentile 1.52 to 6.61 mIU/mL, 17 women Day −11 (day 3 of a 28-day cycle): median 3.82 mIU/mL, 5th to 95th percentile 2.50 to 7.81 mIU/mL, 19 women Day −10 (day 4 of a 28-day cycle): median 3.82 mIU/mL, 5th to 95th percentile 2.24 to 8.73 mIU/mL, 20 women Day −9 (day 5 of a 28-day cycle): median 4.26 mIU/mL, 5th to 95th percentile 2.43 to 7.39 mIU/mL, 20 women Day −8 (day 6 of a 28-day cycle): median 4.96 mIU/mL, 5th to 95th percentile 2.76 to 7.52 mIU/mL, 20 women Day −7 (day 7 of a 28-day cycle): median 4.54 mIU/mL, 5th to 95th percentile 3.57 to 7.90 mIU/mL, 20 women Day −6 (day 8 of a 28-day cycle): median 4.47 mIU/mL, 5th to 95th percentile 3.26 to 7.03 mIU/mL, 20 women Day −5 (day 9 of a 28-day cycle): median 4.18 mIU/mL, 5th to 95th percentile 3.11 to 6.68 mIU/mL, 20 women Day −4 (day 10 of a 28-day cycle): median 4.58 mIU/mL, 5th to 95th percentile 3.29 to 6.89 mIU/mL, 20 women Day −3 (day 11 of a 28-day cycle): median 5.12 mIU/mL, 5th to 95th percentile 3.31 to 7.35 mIU/mL, 20 women Day −2 (day 12 of a 28-day cycle): median 7.02 mIU/mL, 5th to 95th percentile 4.58 to 9.64 mIU/mL, 20 women Day −1 (day 13 of a 28-day cycle): median 12.36 mIU/mL, 5th to 95th percentile 6.36 to 19.08 mIU/mL, 20 women Day 0 (day 14 of a 28-day cycle): median 41.19 mIU/mL, 5th to 95th percentile 21.16 to 73.63 mIU/mL, 20 women Day +1 (day 15 of a 28-day cycle): median 14.92 mIU/mL, 5th to 95th percentile 7.47 to 21.38 mIU/mL, 20 women Day +2 (day 16 of a 28-day cycle): median 7.75 mIU/mL, 5th to 95th percentile 3.93 to 13.24 mIU/mL, 19 women Day +3 (day 17 of a 28-day cycle): median 6.26 mIU/mL, 5th to 95th percentile 3.15 to 11.00 mIU/mL, 20 women Day +4 (day 18 of a 28-day cycle): median 6.46 mIU/mL, 5th to 95th percentile 3.42 to 9.98 mIU/mL, 20 women Day +5 (day 19 of a 28-day cycle): median 4.32 mIU/mL, 5th to 95th percentile 2.53 to 9.19 mIU/mL, 19 women Day +6 (day 20 of a 28-day cycle): median 4.50 mIU/mL, 5th to 95th percentile 1.32 to 10.75 mIU/mL, 20 women Day +7 (day 21 of a 28-day cycle): median 4.29 mIU/mL, 5th to 95th percentile 1.04 to 7.20 mIU/mL, 20 women Day +8 (day 22 of a 28-day cycle): median 3.89 mIU/mL, 5th to 95th percentile 1.58 to 5.90 mIU/mL, 20 women Day +9 (day 23 of a 28-day cycle): median 3.07 mIU/mL, 5th to 95th percentile 0.73 to 6.51 mIU/mL, 20 women Day +10 (day 24 of a 28-day cycle): median 1.75 mIU/mL, 5th to 95th percentile 0.97 to 6.34 mIU/mL, 19 women Day +11 (day 25 of a 28-day cycle): median 2.52 mIU/mL, 5th to 95th percentile 0.49 to 6.05 mIU/mL, 20 women Day +12 (day 26 of a 28-day cycle): median 3.42 mIU/mL, 5th to 95th percentile 0.42 to 7.29 mIU/mL, 20 women Day +13 (day 27 of a 28-day cycle): median 2.55 mIU/mL, 5th to 95th percentile 1.19 to 6.05 mIU/mL, 16 women Day +14 (day 28 of a 28-day cycle): median 3.23 mIU/mL, 5th to 95th percentile 0.85 to 6.20 mIU/mL, 9 women
Median 5th to 95th percentile LH in mIU/mL or IU/L, by day from the LH peak. Point at a day to read its figures; the table below lists every value.

LH in each phase of the cycle

Pooled median LH in each phase, Stricker and colleagues (2006), Table 2
Phase Days from the LH peak Median, mIU/mL or IU/L
Early follicular Days −15 to −6 3.96
Late follicular Days −5 to −1 5.68
LH peak Day 0 41.19
Early luteal Days +1 to +4 7.86
Mid-luteal Days +5 to +9 3.88
Late luteal Days +10 to +14 2.75

Each phase figure is the median of every sample taken in that phase, pooled, which is why it is not the median of the daily medians.

LH on every day of the cycle

The second column places each day in a 28-day cycle with the LH peak on day 14, the textbook timing. Days −15 and −14 have no place in such a cycle, so it is blank for them.

Daily median, 5th and 95th percentile LH, Stricker and colleagues (2006), Table 1
Day from the LH peak Day of a 28-day cycle Women mIU/mL or IU/L
Median 5th 95th
−15 9 2.28 0.37 5.79
−14 12 3.39 1.35 6.29
−13 1 15 3.47 2.35 7.36
−12 2 17 3.59 1.52 6.61
−11 3 19 3.82 2.50 7.81
−10 4 20 3.82 2.24 8.73
−9 5 20 4.26 2.43 7.39
−8 6 20 4.96 2.76 7.52
−7 7 20 4.54 3.57 7.90
−6 8 20 4.47 3.26 7.03
−5 9 20 4.18 3.11 6.68
−4 10 20 4.58 3.29 6.89
−3 11 20 5.12 3.31 7.35
−2 12 20 7.02 4.58 9.64
−1 13 20 12.36 6.36 19.08
0 14 20 41.19 21.16 73.63
+1 15 20 14.92 7.47 21.38
+2 16 19 7.75 3.93 13.24
+3 17 20 6.26 3.15 11.00
+4 18 20 6.46 3.42 9.98
+5 19 19 4.32 2.53 9.19
+6 20 20 4.50 1.32 10.75
+7 21 20 4.29 1.04 7.20
+8 22 20 3.89 1.58 5.90
+9 23 20 3.07 0.73 6.51
+10 24 19 1.75 0.97 6.34
+11 25 20 2.52 0.49 6.05
+12 26 20 3.42 0.42 7.29
+13 27 16 2.55 1.19 6.05
+14 28 9 3.23 0.85 6.20

All 20 women were sampled on 20 of the 30 days. The ends of the table rest on fewer, 9 on day −15 and 9 on day +14, because cycles differ in length. With 20 women or fewer on a day, each percentile is set by the one or two most extreme values.

How LH moves through the cycle

Through the follicular phase, days −15 to −3, the median stays between 2.28 and 5.12 mIU/mL. It is 7.02 by day −2, part of a slower climb ahead of the surge: in the women Hoff, Quigley and Yen sampled, LH, estradiol and progesterone each doubled in 57 to 61 hours before the surge began.

A surge lasts about 48 hours: 14 rising, 14 at its peak and 20 falling, in their sampling of 5 women every 2 hours. A daily sample catches some women on its rising limb and others on its falling one, so the median is already 12.36 mIU/mL the day before the peak and still 14.92 the day after, and the band on day 0 is the widest in the table, 52.47 mIU/mL from the 5th to the 95th percentile.

By day +2 the median has fallen to 7.75 mIU/mL, and through the luteal phase it drifts down to the table’s lowest, 1.75 mIU/mL on day +10.

The menstrual cycle hormone simulator joins these medians into curves and plays LH against the other three hormones, with the follicle and the lining drawn day by day.

Converting between units

An international unit measures biological activity against a WHO reference preparation rather than a mass, so LH has no molar mass to convert with, and needs none: a milli-international unit per milliliter scales the unit and the volume by the same thousand, so mIU/mL and IU/L carry the same number.

mIU/mL to IU/L

  1. 1 mIU/mL = 0.001 IU ÷ 0.001 L
  2. = 1 IU/L

Where the numbers come from

Stricker and colleagues (2006) took blood from 20 women aged 20 to 36, with normal cycles and no hormonal contraception, on every day of one cycle, and measured LH on an Abbott ARCHITECT analyzer in one laboratory. Each woman’s days are counted from her own LH peak, day 0, and each figure is the median of the women sampled that day.

The tables were read from the authors’ own copy of the paper, and every figure was checked against the independent transcription behind Häggström’s reference range charts.

See also

Source: Stricker R and colleagues, “Establishment of detailed reference values for luteinizing hormone, follicle stimulating hormone, estradiol, and progesterone during different phases of the menstrual cycle on the Abbott ARCHITECT analyzer”, Clin Chem Lab Med 2006;44(7):883-887.

The values are facts and free to use; this table’s selection and presentation are © 2026 ScienceQuest.