Evidence Based

Estriol Blood Test: High & Low Levels + Normal Range

Written by Joe Cohen, BS | Last updated:
Jonathan Ritter
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology) | Written by Joe Cohen, BS | Last updated:

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Estriol is one of the three main estrogens. Learn the common causes of high & low estriol and natural hacks to increase & decrease it here.

What is Estriol?

The three main estrogens in the body are estrone (E1), estradiol (E2), and estriol (E3). This test measures the amount of estriol in your blood.

In women, estriol is produced in the ovarian follicles and corpus luteum. Estrone and estradiol can also be converted into estriol [1, 2, 3].

Normally, in both men and women, estriol levels are the lowest compared to the other two estrogens and cannot be detected in the blood (serum). Estriol levels increase during pregnancy. After the third semester, the placenta converts DHEA-S into estriol and other estrogens. Estriol becomes the major estrogen, peaking during the third trimester. After a woman gives birth, her estriol levels will decrease and go back to normal [4, 1].

Estriol tests are used to monitor high-risk pregnancies and screen for problems with the fetus [5].

Normal Range of Estriol

Quest provides the following ranges:

Adult Male≤0.18 ng/mL
Adult Female (Non-pregnant)≤0.21 ng/mL
 First trimester≤2.50 ng/mL
 Second trimester≤9.60 ng/mL
 Third trimester≤14.60 ng/mL

Low Estriol

In pregnant women, low estriol levels may be caused by:

  • Steroid sulfatase deficiency [6, 7]
  • The inability of the adrenal glands to produce enough hormones (adrenal insufficiency) [7]

Some drugs can also lower estriol levels:

  • Corticosteroids [8]
  • Propylthiouracil, a drug used to treat Grave’s disease and overactive thyroid gland (hyperthyroidism) [8]

Having low levels are associated with a higher risk of:

  • Restricted growth of the fetus and low birth weight [9]
  • Preeclampsia (high blood pressure, high levels of protein in the urine, and swelling in the hands and feet during pregnancy) [10]
  • Birth defects and disorders in the baby, such as Down syndrome and X-linked adrenal hypoplasia congenita [11, 5]
  • Pregnancy loss [12]
  • Early death [13]

Symptoms of low Estriol include:

  • Mood swings [14]
  • Headaches [15]
  • Increased urinary tract infections (UTIs) [16]
  • Absent or irregular periods [17]
  • Depression [18]

Low Estriol Recommendations

Since estriol can be derived from other estrogens, increasing your estrone and estradiol levels may help increase estriol levels [3].

Practicing yoga can help increase estrogen and improve the quality of life of postmenopausal women [19].

Eat more vegetables and grains that contain fiber. Increasing your dietary fiber intake also increases estrogen [20].

Supplements that can help increase estrogens:

High Estriol

In women, the most common cause of high estriol levels is pregnancy [25].

If you are pregnant, optimal estriol values will depend on the gestational week. Check your lab ranges and consult your doctor for more information.

Recommendations for High Estriol:

  • Exercise [26]
  • Reducing your body fat [27]
  • Increasing the intake of foods containing natural aromatase inhibitors, including mushrooms, celery, carrots, spinach, grapes, etc. [28]
  • Reducing alcohol consumption [29]
  • Reducing carbs in your diet, since a high carbohydrate diet can increase estrogen levels [30]
  • Increasing your intake of vegetables that contain indole-3-carbinol, such as cabbage, cauliflower, broccoli, and kale [31, 32]
  • Zinc, selenium, and magnesium [33]

Irregular Estriol Levels?

LabTestAnalyzer helps you make sense of your lab results. It informs you which labs are not in the optimal range and gives you guidance about how to get them to optimal. It also allows you to track your labs over time. No need to do thousands of hours of research on what to make of your lab tests.

LabTestAnalyzer is a sister company of SelfHacked. The proceeds from your purchase of this product are reinvested into our research and development, in order to serve you better. Thank you for your support.

About the Author

Joe Cohen, BS

Joe Cohen, BS

Joe Cohen won the genetic lottery of bad genes. As a kid, he suffered from inflammation, brain fog, fatigue, digestive problems, anxiety, depression, and other issues that were poorly understood in both conventional and alternative medicine.Frustrated by the lack of good information and tools, Joe decided to embark on a journey of self-experimentation and self-learning to improve his health--something that has since become known as “biohacking”. With thousands of experiments and pubmed articles under his belt, Joe founded SelfHacked, the resource that was missing when he needed it. SelfHacked now gets millions of monthly readers.Joe is a thriving entrepreneur, author and speaker. He is the CEO of SelfHacked, SelfDecode and LabTestAnalyzer.His mission is to help people gain access to the most up-to-date, unbiased, and science-based ways to optimize their health.
Joe has been studying health sciences for 17 years and has read over 30,000 PubMed articles. He's given consultations to over 1000 people who have sought his health advice. After completing the pre-med requirements at university, he founded SelfHacked because he wanted to make a big impact in improving global health. He's written hundreds of science posts, multiple books on improving health, and speaks at various health conferences. He's keen on building a brain-trust of top scientists who will improve the level of accuracy of health content on the web. He's also founded SelfDecode and LabTestAnalyzer, popular genetic and lab software tools to improve health.

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