LH (Luteinising hormone)
The pituitary signal that tells the testes to produce testosterone.
What it is
LH is released in pulses from the anterior pituitary and acts on Leydig cells in the testes, driving testosterone production. It is regulated by GnRH from the hypothalamus and inhibited by feedback from circulating testosterone and oestradiol.
Why it matters
LH is the only marker that tells you whether a low testosterone result is the testes failing (high LH, signal is loud but no response) or the brain failing to send the signal (low LH).
Adult male reference range
Adult male reference range is roughly 1.7–8.6 IU/L. Pulsatile release means single readings can vary by ~30%.
Role on the panel
On the Hormone Panel 01, LH localises the level of any androgen problem and is decisive when interpreting a borderline testosterone value.
When it reads low
Low LH with low testosterone = secondary hypogonadism. Common causes include exogenous testosterone, opioids, prolactinoma, severe stress / under-eating and rare pituitary disease.
When it reads high
Elevated LH with low testosterone = primary hypogonadism. The pituitary is shouting; the testes are not answering.
Common questions about this marker.
Order the Hormone Panel 01.
All six markers, one finger-prick, ISO-certified German lab. Physician review and a plain-language report in 3–5 working days.