Sex Hormones: Lab Testing

Bryan Knowles
Feb 17
6 min read

Updated: Aug 11

People are saying there's a sex recession. There is no recession for sex hormone lab testing. The amount of people getting tested for testosterone and other related labs have spiked in recent years with the use of testosterone replacement therapy (TRT) and other reproductive interventions such as in vitro fertilization (IVF). These tests are helpful on multiple levels:

Diagnosis of hormone deficiencies or dysregulation

Help with reproductive health and infertility issues

Hormone replacement therapy for post-menopausal women

Tumor detection and monitoring

I won't get into the hot-button issues here, but you know what I'm talking about. So, let's get acquainted with commonly ordered sex-hormones.

Testosterone

This is a big one right now. Testosterone is the primary male sex hormone, though it is also present in females in smaller amounts. It plays a crucial role in the development of male reproductive tissues, muscle mass, bone density, and secondary sexual characteristics such as body hair and deepening of the voice. In laboratory testing, testosterone levels are measured to assess conditions like hypogonadism, infertility, polycystic ovary syndrome (PCOS), and androgen-secreting tumors. Testing may involve measuring total testosterone, which includes both bound and unbound testosterone in the bloodstream, or free testosterone, which represents the biologically active portion. Levels can vary based on age, time of day, and underlying health conditions.

Estrogen (Estradiol, Estrone, and Estriol)

Estrogen is a group of hormones primarily responsible for the development and regulation of the female reproductive system and secondary sexual characteristics. Estradiol is the most potent and prevalent estrogen in premenopausal women, estrone is more dominant after menopause, and estriol is primarily associated with pregnancy. Laboratory testing of estrogen levels is used to evaluate menstrual irregularities, fertility concerns, menopause, and hormone-related disorders such as estrogen-producing tumors. In men, estrogen testing may help assess gynecomastia, testicular function, or hormonal imbalances.

Progesterone

Progesterone is essential for regulating the menstrual cycle and maintaining pregnancy. It is produced by the ovaries after ovulation and supports the uterine lining in preparation for a fertilized egg. During pregnancy, the placenta takes over progesterone production to sustain fetal development. Laboratory testing of progesterone is commonly performed to confirm ovulation, assess fertility, monitor pregnancy, and investigate conditions such as luteal phase defects or progesterone-producing tumors. In some cases, testing may also help evaluate adrenal function.

Bananas and cherries. Nothing sexual here.

Luteinizing Hormone (LH)

Luteinizing hormone plays a vital role in the reproductive system by triggering ovulation in females and stimulating testosterone production in males. It is secreted by the pituitary gland and fluctuates in a predictable pattern based on the menstrual cycle in women. LH levels are commonly measured to evaluate fertility issues, irregular menstruation, polycystic ovary syndrome, and pituitary disorders. In men, LH testing helps assess testicular function, particularly in cases of hypogonadism or delayed puberty.

Follicle-Stimulating Hormone (FSH)

Follicle-stimulating hormone is crucial for reproductive function in both men and women. In females, it promotes the growth and maturation of ovarian follicles, while in males, it supports sperm production. Laboratory testing of FSH levels is used to diagnose conditions such as ovarian insufficiency, menopause, infertility, and polycystic ovary syndrome. In men, it helps evaluate testicular function and sperm production, particularly in cases of unexplained infertility or hormonal imbalances.

Prolactin

Prolactin is primarily known for its role in stimulating breast milk production after childbirth, but it also has broader functions in regulating reproductive and immune system activity. Elevated prolactin levels, a condition known as hyperprolactinemia, can cause menstrual irregularities, infertility, and reduced libido in both men and women. Laboratory testing of prolactin is often performed when investigating unexplained galactorrhea (milk production outside of pregnancy or breastfeeding), pituitary gland disorders, or certain types of tumors such as prolactinomas.

Dehydroepiandrosterone (DHEA) and DHEA-Sulfate (DHEA-S)

DHEA is an androgen precursor hormone produced by the adrenal glands and is converted into testosterone and estrogen in the body. DHEA sulfate (DHEA-S) is the more stable, sulfated form of DHEA and is commonly measured in laboratory testing to assess adrenal function. Elevated DHEA-S levels can indicate adrenal hyperplasia, adrenal tumors, or polycystic ovary syndrome, while low levels may be associated with adrenal insufficiency or certain chronic conditions. Testing is often used in conjunction with other hormone assessments to determine the cause of androgen excess or deficiency.

Sex Hormone-Binding Globulin (SHBG)

Sex hormone-binding globulin is a protein that binds to sex hormones, primarily testosterone and estrogen, regulating their bioavailability in the bloodstream. Laboratory testing of SHBG levels helps interpret testosterone and estrogen activity, particularly in cases of hormonal imbalances such as polycystic ovary syndrome, liver disease, and insulin resistance. SHBG levels can be affected by various factors, including age, obesity, thyroid disorders, and certain medications, making its measurement a useful tool in assessing overall hormonal function.

These hormone tests are fundamental in diagnosing and managing a wide range of reproductive, endocrine, and metabolic disorders. Their interpretation often requires consideration of multiple factors, including patient history, symptoms, and additional laboratory results, to provide a comprehensive understanding of hormonal health.

HCG

Quantitative Human Chorionic Gonadotropin (hCG) Testing and Its Pattern During Pregnancy

Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced primarily by the syncytiotrophoblast cells of the developing placenta shortly after the fertilized egg implants in the uterine lining. Quantitative hCG testing measures the exact concentration of this hormone in the blood, expressed in milli-international units per milliliter (mIU/mL), and plays a critical role in the detection, dating, and monitoring of pregnancy, as well as in the evaluation of certain pathological conditions.

There are two ways HCG is tested: Qualitative and Quantitative. Qualitative is the same things people do at home with kits off the shelf from the pharmacy. Quantitative is generally only done to measure where a pregnancy or miscarriage is in its course.

Physiology and Function of hCG

After ovulation, if fertilization occurs, the blastocyst implants into the endometrium approximately 6 to 10 days post-conception. Shortly thereafter, hCG begins to be secreted into the maternal circulation. This hormone’s primary role in early pregnancy is to maintain the corpus luteum, which produces progesterone and estrogen to support the endometrial lining until the placenta can assume full hormonal production. Beyond its reproductive role, hCG has growth-promoting and immunomodulatory effects, helping to ensure successful implantation and placental development.

Clinical Uses of Quantitative hCG Testing

In clinical practice, quantitative hCG measurement is used for early pregnancy detection, as levels can be detected in serum as early as 8 to 11 days after conception, preceding the first missed menstrual period. Serial quantitative measurements, often spaced 48 hours apart, are used to assess the viability of early pregnancy. In a normal intrauterine pregnancy during the first trimester, hCG levels typically double every 48 to 72 hours. Slower rises may indicate ectopic pregnancy or impending pregnancy loss, whereas abnormally high levels may be seen in multiple gestations or gestational trophoblastic disease.

Quantitative hCG testing also plays a role in pregnancy dating when the last menstrual period is uncertain, although it is most accurate in the early weeks before ultrasound becomes the preferred method. Outside of pregnancy, elevated hCG levels can be seen in trophoblastic tumors (such as hydatidiform mole or choriocarcinoma) and in certain germ cell tumors, making it a useful tumor marker in oncology.

Typical hCG Curve During Pregnancy

The concentration of hCG in maternal serum follows a characteristic curve over the course of pregnancy. After initial appearance in the blood shortly after implantation, levels rise exponentially during the first trimester, doubling approximately every 2 to 3 days and peaking between 8 and 11 weeks of gestation, often reaching 100,000 mIU/mL or more. After this peak, levels gradually decline and stabilize during the second trimester, remaining at a plateau for the remainder of the pregnancy.

In the third trimester, hCG levels are relatively steady or may show a slight decline. The physiological reason for this decline after the first trimester is the transition of progesterone and estrogen production from the corpus luteum to the placenta, reducing the need for high hCG stimulation.

Approximate hCG Ranges by Gestational Age

While values can vary greatly between individuals, the following serum ranges illustrate the typical progression: