What are normal prepubertal Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) levels?

Prepubertal LH and FSH Levels

In prepubertal children, LH levels are extremely low (mean 0.04-0.6 IU/L) and FSH levels are measurably higher (mean 0.8-2.0 IU/L), with both hormones remaining suppressed until the onset of puberty. 1, 2

Normal Prepubertal Ranges

Luteinizing Hormone (LH)

• Basal LH levels in prepubertal girls: 0.04 ± 0.04 IU/L using highly sensitive immunochemiluminometric assays 1
• Alternative studies report prepubertal ranges of 0.6 ± 0.7 IU/L in girls and 1.8 ± 1.0 IU/L in boys 2
• All prepubertal children under age 10 years have LH concentrations below 0.2 IU/L 3
• LH levels remain steady throughout the prepubertal period with minimal variation 4

Follicle-Stimulating Hormone (FSH)

• Basal FSH levels in prepubertal girls: 0.8 ± 0.1 IU/L 4
• Alternative measurements show 1.5 ± 0.8 IU/L in prepubertal girls and 2.0 ± 0.8 IU/L in prepubertal boys 2
• FSH levels range from 0.3-2.0 IU/L in children under 10 years 3
• FSH concentrations are consistently higher than LH throughout the prepubertal period 1, 5

Clinical Context and Assessment

When to Measure Prepubertal Gonadotropins

• Baseline LH, FSH, and estradiol should be assessed at age 13 years in prepubertal survivors of cancer or those at risk of delayed puberty 6
• Prepubertal females age ≥11 years with failure to initiate or progress through puberty require laboratory evaluation 6, 7
• FSH and estradiol measurement is recommended for prepubertal females with signs suggestive of premature ovarian insufficiency 6

GnRH Stimulation Testing

• Peak GnRH-stimulated LH in prepubertal children: 1.8 ± 1.3 IU/L (identical in boys and girls) 1
• GnRH-stimulated LH response in prepubertal girls: 4.1 ± 2.3 IU/L 2
• GnRH-stimulated FSH response is markedly elevated in prepubertal girls: 8.0 ± 1.0 IU/L, which gradually decreases toward puberty onset 4
• A GnRH-stimulated LH level >5 IU/L suggests maturing gonadotropin secretion and pubertal transition 1

Pubertal Transition Markers

Magnitude of Change at Puberty

• LH increases approximately 100-fold from prepuberty to adulthood (from mean 0.05 IU/L to 5.8 IU/L) 1, 3
• FSH increases only 3-7 fold during puberty (much smaller change than LH) 1, 3
• Peak GnRH-stimulated LH increases 20-fold at puberty 1

Critical Thresholds

• An FSH cut-off ≥10 IU/L at age 10 years or older indicates ovarian impairment requiring pubertal induction in conditions like Turner syndrome 6
• Elevated FSH levels (>35 IU/L) with LH >11 IU/L indicate hypergonadotropic hypogonadism 6

Important Clinical Considerations

Assay Sensitivity Matters

• Modern immunochemiluminometric assays (ICMA) are essential for accurate prepubertal LH measurement, as older radioimmunoassays lack sensitivity at low concentrations 1
• Spontaneous LH can be accurately measured by ICMA to the very low levels present in normal prepubertal children, providing important biochemical discrimination of pubertal status 1

Pulsatile Secretion

• Both LH and FSH demonstrate pulsatile secretion even in prepubertal children, though with lower amplitude and frequency than in pubertal individuals 5
• Single random measurements may not fully capture gonadotropin reserve without GnRH stimulation 2

When to Refer

• Refer to pediatric endocrinology when prepubertal females have no signs of puberty by age 13 years with elevated FSH levels at laboratory screening 6, 7
• Refer for failure to initiate or progress through puberty in prepubertal females age ≥11 years 6