22 Aug What is LH (luteinising hormone)?
LH, or luteinising hormone, plays an important role in reproductive health. For couples finding it hard to conceive or maintain a pregnancy, the amount of LH in the blood is relevant. If you’re considering IVF, an LH test is a must.
LH is a glycoprotein hormone made by the pituitary gland. It helps to create sperm, but it’s more widely understood – together with FSH – as facilitating egg production in women. You may have heard about the LH surge: the marked rise in the hormone, mid-cycle. This initiates ovulation.
But there’s more to LH than the LH surge. LH levels at the start of your cycle, together with other blood-hormone tests, can reveal a lot about your fertility health. They form part of a snapshot of your ovarian reserve. They green-light your luteal function. And they can show if you’re menopausal.
An LH urine test can be used to check if your LH has triggered ovulation. For IVF patients, an LH blood test in the first three days of your cycle is standard. LH plays a key role in follicle growth. The score allows your fertility clinic to fine-tune your protocol. If your LH score is too close to your FSH score, or higher, you probably have PCOS. If it’s a third to a half lower, you probably don’t.
LH levels vary, depending on your age, health and where you are in your cycle. It’s not an exact science, but broad rules apply. A normal result is usually somewhere between 2.4 and 12.6 IU/L in the follicular phase. At its peak, in the middle of your cycle, a healthy LH reading can be anywhere between 14.0 and 95.6. In the luteal phase, it’s 1.0 to 11.4. Post-menopause, the reference range is 7.7 to 58.5.
Higher readings may suggest an ovarian problem such as PCOS, which may impact on the quality of your eggs and uterine lining – and thus your chances of success, via IVF or otherwise. Low results may point to an issue with your pituitary or hypothalamus, an eating disorder, or other problems. In men, a super-low LH reading may suggest a sperm-production issue.
Verdict? An LH problem is one of several factors that may contribute to difficulties conceiving. A too-low or too-high LH level does not, in itself, automatically preclude a successful conception. It merely tells you and your doctor that there’s an issue that has to taken into account. Indeed, one study has suggested that a day-three LH test for IVF patients is not a reliable indicator of future IVF success. The study was not widely accepted, though.
So while LH is an important sex hormone, IVF and fertility-challenged patients should not be too discouraged if their LH readings are out of the normal range (which can, in any case, vary from lab to lab). Many of our IVF patients have had babies, despite sub-normal LH scores. There are plenty of other tests and procedures to help you decide if you’re a viable fertility patient.