Normal IGF-1 by age and sex: Free Reference Figure

Normal IGF-1 by age and sex

The normal range of IGF-1 falls steadily with age in both sexes. Each bar spans the 2.5th to 97.5th percentile of a healthy reference population, with the median marked, from a 15,014-person study.

Two range charts of normal IGF-1 in ng/mL by age band, men and women aged 21 to 90. Each band shows the 2.5th to 97.5th percentile range and the median. The median falls from about 217 ng/mL in men aged 21 to 25 to about 85 ng/mL at 86 to 90, and from about 196 to 90 ng/mL in women.

Klarovel (klarovel.com), CC BY 4.0. Open the full-size PNG

IGF-1 is the usual blood marker for how active the growth hormone axis is, and what counts as normal depends heavily on age. In men the median falls from about 217 ng/mL at 21 to 25 to about 106 ng/mL at 61 to 65; in women from about 196 to 94 ng/mL over the same years. A value that is ordinary at 25 can be well above the normal range at 65.

That is why labs and clinicians often express IGF-1 as a standard deviation score (SDS) for age and sex rather than as a raw number. The bars here span the central 95% of a healthy reference population, which corresponds to an SDS of about -2 to +2.

These reference values come from one assay (IDS-iSYS, calibrated to the WHO 02/254 standard). Other lab platforms give somewhat different numbers, so a result is best compared with the range printed on its own lab report. To convert ng/mL to nmol/L, multiply by 0.131.

IGF-1 reference percentiles, ng/mL (2.5th / median / 97.5th)
Age	Men 2.5th	Men median	Men 97.5th	Women 2.5th	Women median	Women 97.5th
18	146.2	292	493.6	120.5	270	485.8
19	140.2	276.1	462.7	114.4	252.6	450.8
20	133.1	258.5	430	107.8	234.8	416
21-25	115.2	217.2	354.8	92.9	196.2	342
26-30	97.9	176.8	281.6	78.4	158.7	270
31-35	88.3	156.4	246	73.1	144.7	243
36-40	83.4	147.9	232.7	69	135.7	227
41-45	74.9	135.7	216.4	61.5	121.7	204.4
46-50	66.9	125.7	205.1	56.8	114.5	194.5
51-55	60.6	119.4	200.3	53	109.9	189.6
56-60	54.3	112.5	194.2	45.6	98	172.4
61-65	48.8	106	187.7	42.2	94.1	169
66-70	46.5	105.8	191.9	38.3	88.7	162.5
71-75	40.9	96.7	179.2	36.6	88.2	164.7
76-80	37.1	91.1	172	34.7	86.7	164.8
81-85	33.8	86.1	165.4	34.4	89.1	172.4
86-90	32.2	85	166.1	33.6	90.3	177.8

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<figure>
  <img src="https://www.klarovel.com/en/figures/igf1-by-age.png" alt="Two range charts of normal IGF-1 in ng/mL by age band, men and women aged 21 to 90. Each band shows the 2.5th to 97.5th percentile range and the median. The median falls from about 217 ng/mL in men aged 21 to 25 to about 85 ng/mL at 86 to 90, and from about 196 to 90 ng/mL in women." width="1200" height="900" loading="lazy">
  <figcaption>Normal IGF-1 by age and sex. Source: <a href="https://www.klarovel.com/en/figures/igf1-by-age">Klarovel</a>, <a href="https://creativecommons.org/licenses/by/4.0/">CC BY 4.0</a>.</figcaption>
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Normal IGF-1 by age and sex

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