Blood Lab Values for Diagnosing Hypothalamic Amenorrhea (HA)
- Elina Karlsson
- Sep 9, 2024
- 3 min read
Hypothalamic Amenorrhea (HA) Is a Diagnosis of Exclusion
It’s important to understand that Hypothalamic Amenorrhea (HA) is a diagnosis of exclusion. This means your healthcare provider must rule out other medical causes of missing periods before confirming it. These may include:
Thyroid dysfunction
Hyperprolactinemia (elevated prolactin)
Primary ovarian insufficiency
Uterine or structural abnormalities (e.g., Asherman’s syndrome)
Once these are excluded, your health care provider will continue investigating if Hypothalamic Amenorrhea (HA) might be the cause of your missing period.
Blood Lab Values for Diagnosing Hypothalamic Amenorrhea (HA)
When diagnosing Hypothalamic Amenorrhea (HA), your doctor will typically look at several hormones to assess reproductive function. These values help piece together the hormonal pattern of energy deficiency and suppression of the hypothalamic-pituitary-ovarian (HPO) axis.
Equally important—but too often overlooked—is a thorough evaluation of lifestyle factors such as nutrition, exercise habits, stress levels, and recent weight changes. Many healthcare providers focus solely on lab results, missing the bigger picture of low energy availability and Hypothalamic Amenorrhea (HA). A detailed lifestyle history is essential for a complete and accurate diagnosis.
Hormone / Marker | Normal Range (Approx.) | In Hypothalamic Amenorrhea (HA) | Why It Matters |
FSH | 3-10 IU/L | Low or low-normal | Signals ovaries to grow follicles; reduced due to suppressed GnRH |
LH | 2-15 IU/L (varies by cycle phase) | Low or lower than FSH | Critical for ovulation; typically suppressed in Hypothalamic Amenorrhea (HA) |
LH:FSH Ratio | ~1:1 or slightly >1 | Often <1 (reversed ratio) | A reversed ratio is typical in Hypothalamic Amenorrhea (HA); opposite of PCOS profile |
Estradiol (E2) | 70–500 pmol/L (20–140 pg/mL) | Very low (<100 pmol/L / <30 pg/mL) | Indicates estrogen production |
Prolactin | <500 mIU/L (varies by lab) | Normal or low | High levels can cause amenorrhea, so used to rule out other causes |
TSH | 0.4–4.0 mIU/L (0.4-2.5 for women in fertile age) | Normal | |
Free T3 | 3.1–6.8 pmol/L | Low | Shows reduced metabolic rate from energy deficiency |
Table Blood Lab Values for Diagnosing Hypothalamic Amenorrhea (HA)
Normal range: ~3–10 IU/L
In Hypothalamic Amenorrhea (HA): Usually low or low-normal
Why it matters: FSH signals the ovaries to develop follicles. A suppressed FSH reflects the brain's downregulation of reproductive signaling in response to perceived stress or energy shortage.
Normal range: ~2–15 IU/L (depending on cycle phase)
In Hypothalamic Amenorrhea (HA): Low or lower than FSH
Why it matters: LH triggers ovulation. In Hypothalamic Amenorrhea (HA), the hypothalamus reduces gonadotropin-releasing hormone (GnRH) output, leading to suppressed LH levels.
LH:FSH Ratio
Typical ratio: ~1:1 or slightly higher
In Hypothalamic Amenorrhea (HA): Often <1
Why it matters: A reversed LH:FSH ratio is a hallmark of Hypothalamic Amenorrhea (HA), helping to distinguish it from PCOS, where LH is often elevated relative to FSH.
Estradiol (E2)
Normal range (follicular phase): ~70–500 pmol/L (20–140 pg/mL)
In Hypothalamic Amenorrhea (HA): Often very low (<100 pmol/L or <30 pg/mL)
Why it matters: Estradiol is a key form of estrogen. Persistently low levels can lead to infertility, bone loss, and mood disturbances.
Prolactin
Normal range: <500 mIU/L (varies by lab)
In Hypothalamic Amenorrhea (HA): Typically normal or low
Why it matters: Elevated prolactin can cause amenorrhea by suppressing GnRH. Testing helps rule out other causes like a pituitary tumor (prolactinoma).
Thyroid Hormones (TSH, Free T3, Free T4)
In Hypothalamic Amenorrhea (HA): TSH is often normal, but Free T3 is usually low
Why it matters: Free T3 reflects metabolic activity. A low Free T3 is common in energy deficiency and shows how the body is slowing down to conserve energy.
Final Thoughts
Bloodwork is one tool when trying to understand what’s happening with your hormones, but numbers alone don’t tell the full story. Hypothalamic Amenorrhea (HA) is your body’s way of saying, “I don’t feel safe enough to reproduce right now.” It’s not broken—it’s protecting you.
The good news? You can reverse it. With more nourishment, less stress, and a shift in mindset, your body can return to balance—and your cycle can return too.
*All content is for informational purposes only. It is not intended to be a substitute for professional medical advice. Always seek the guidance of your doctor or other qualified health professional with any questions you may have regarding your health or a medical condition. If you suspect you have a luteal phase deficiency or are experiencing difficulty conceiving, it's advisable to consult with a healthcare professional or a fertility specialist for a thorough evaluation and personalized guidance.
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