7 Lab Tests Every Woman in Her 30s Should Know, According to Dr. Sara Szal

If you’ve ever felt like burnout sneaks up out of nowhere—hello 3 a.m. wakeups and brain fog—it might not just be “in your head.” According to Dr. Sara Szal on Treated With Dr. Sara, stress shows up in your biomarkers long before it takes you down. 

Szal calls them the “burnout seven”—lab tests and markers that reveal whether your hormones, sleep, and stress response are working for you or against you. “You can’t think your way out of burnout. You have to measure your way out,” she explains. Below, here are the seven key lab tests every woman should have on her radar in her thirties.

1. Check your heart rate variability (HRV)

“If you only track one thing after this episode, let it be heart rate variability,” Szal says. HRV measures the tiny variation in milliseconds between heartbeats and reveals how resilient your nervous system is.

High HRV means your body knows how to recover, while low HRV usually signals you’re stuck in fight-or-flight mode. Szal notes that HRV tends to drop right before a burnout crash, making it an early red flag worth watching.

2. Track progesterone levels

Many women assume their cycle is healthy as long as their period shows up—but ovulation can quietly disappear before menstruation does. “Most high achieving women stop ovulating before they stop having periods. That means that progesterone plummets, but no one is noticing,” Szal explains. 

Low progesterone can bring on anxiety, poor sleep, irritability, and it can even increase your risk of burnout. Keeping tabs on your luteal phase and confirming ovulation can help you spot these hormonal shifts early.

3. Measure cortisol the right way

A single morning cortisol blood draw doesn’t tell the full story. Instead, Szal recommends the cortisol awakening response (CAR), which measures how your body reacts to stress the moment you wake up.

“If you have a flat CAR, so it’s a flat line, or a blunted cortisol awakening response, this can be a burned out adrenal response,” she explains. A spiky or delayed curve can also suggest your body is stuck in survival mode. Salivary at-home tests can give a clearer picture than a one-off blood test.

4. Look at free T3 and reverse T3

Stress doesn’t just wear you out mentally—it also affects your thyroid. “In women, chronic stress reduces the conversion of T4 into T3. T3 is your active thyroid hormone. T4 is your storage thyroid hormone. And instead of this normal conversion, it gets shunted into reverse T3, which is the metabolic equivalent of a parking break,” says Szal.

Symptoms of this imbalance include brain fog, cold hands and feet, sluggish digestion, and low mood. Even if your TSH looks normal, checking the ratio of free T3 to reverse T3 can reveal what’s really going on.

5. Don’t skip ferritin

Iron deficiency is common for women in their thirties, especially postpartum or during heavy cycles. But anemia isn’t the only concern—your ferritin levels matter too. “Ferritin is how your body stores iron. It’s critical for mitochondria synthesis, oxygen delivery, and mental clarity,” Szal says.

Low ferritin can trigger fatigue, hair loss, and that wired-but-tired feeling. While many labs call a ferritin level of 12 “normal,” Szal points out that women feel best when their levels are between 70 and 100.

6. Prioritize deep sleep over hours slept

Getting eight hours of shut-eye is only part of the equation. “Sleep is when you make hormones, you repair tissues, you consolidate your memory, you do emotional regulation,” Dr. Sara explains. If you fal asleep easily but wake up tired, you may not be getting enough restorative deep sleep. Szal recommends aiming for about 90 minutes of deep sleep each night. Less than that, she warns, could mean burnout is progressing behind the scenes.

7. Watch glucose variability

Blood sugar swings can be just as telling as hormones for burnout. “Even if your A1C is perfect, you can have high glucose variability that’s not picked up by your A1C, and this can reflect cortisol spikes, night wakenings, mood crashes, food cravings, and insulin resistance over time,” says Szal.

She suggests using a continuous glucose monitor or a simple glucose meter to track your body’s response to food. The goal isn’t just about carbs—it’s about spotting how spiky your blood sugar gets throughout the day.

For the full conversation, tune into the Treated With Dr. Sara podcast.

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