Energy & vitality · Low energy
Persistent fatigue
Fatigue that sleep doesn't fix is almost always a physiology signal - not a willpower problem. It's one of the most under-investigated symptoms in women's health, and also one of the most treatable once the right biomarkers are measured.
Feels like
Does this sound like you?
- Wiped out by 3 PM even after a full night's sleep
- Breathless climbing a flight of stairs
- Heavy legs, cold hands and feet
- Brain fog stacked on top of physical tiredness
- Exercise feels harder than it should for your baseline
What to measure
The biomarkers that explain this symptom.
Grouped by the panel that tests them. We usually recommend running the top two panels together - patterns only show when you can see biomarkers next to each other.
Panel
nutrients
- FerritinBelow 30 ng/mL, most women feel classic fatigue, hair shedding, and exercise intolerance - long before hemoglobin flags.
- Vitamin B12Subclinical B12 deficiency presents as cognitive fatigue and tingling extremities.
- Vitamin DLow D is associated with muscle weakness and persistent low energy, especially in winter.
Panel
thyroid
- TSH / Free T4 / Free T3Sluggish thyroid is the #2 cause of unexplained fatigue in women under 50.
Panel
hormones
- Cortisol (AM)Both high AM cortisol (wired-tired) and blunted cortisol curves (burnout) produce fatigue.
- Estradiol, ProgesteroneLuteal-phase hormone withdrawal can mimic chronic fatigue in sensitive women.
Patterns we see
Three common clusters.
Your specific pattern will be unique, but most people land in one of these.
01
Iron-deficient (no anemia)
Ferritin <30, hemoglobin normal. Most common pattern we see in menstruating women.
02
Subclinical hypothyroid
TSH 3.0–4.5, low-normal free T3. Common in postpartum and perimenopause.
03
Luteal crash
Hormones in range but progesterone drops sharply mid-luteal. Symptom-tracking required to catch.
Ready to look?
Order the nutrients + thyroid panels.
Running the top two panels together is what lets us see patterns. Add a third if you want a fuller picture - most people benefit from the trio.
Further reading