Hormone testing is a powerful tool to add to your health toolbox. Understanding hormone levels provides key insight into the body’s regulatory systems. Processes such as metabolism, reproduction, stress response, and immune function all rely on proper hormone signaling—essentially every physiological system is influenced by hormones.
Because of this, hormone balance is critical. When these chemical messengers become imbalanced, the effects are often widespread and frequently misunderstood.
Traditional medicine may begin and end with a basic thyroid check or metabolic panel. However, hormone testing can extend far beyond this. Clinicians can use multiple strategies to assess thyroid, adrenal, gonadal, and metabolic function in order to understand the bigger picture.
This article reviews key hormones, what they measure, why they matter, and how to interpret them.
The thyroid gland plays a central role in regulating metabolism, energy production, body temperature, heart rate, and mood. Despite its importance, an estimated 20 million people in the United States have some form of thyroid dysfunction (1).
Thyroid-stimulating hormone (TSH) is produced by the pituitary gland and serves as the primary signal for thyroid hormone production. It stimulates the thyroid to release T3 and T4.
TSH is often one of the first screening tests when thyroid dysfunction is suspected. Elevated TSH typically indicates hypothyroidism, while low TSH suggests hyperthyroidism (2).
T3 (triiodothyronine) is one of the two primary thyroid hormones. It exists in both free and bound forms. Free T3 is the active form that enters tissues, while bound T3 is attached to proteins.
T3 plays a critical role in metabolic rate, digestive and cardiovascular function, brain development, muscle control, and bone health. Testing is often used to help diagnose hyperthyroidism (3).
T4 (thyroxine) is another key thyroid hormone, also present in free and bound forms. Free T4 is the biologically active form, while bound T4 serves as a circulating reserve.
T4 testing helps evaluate both hypothyroidism and hyperthyroidism (4).
Sex hormones influence far more than reproduction. They affect bone density, cognition, cardiovascular health, body composition, and mental health.
Estradiol is a type of estrogen produced primarily by the ovaries, as well as the adrenal glands and peripheral tissues. During pregnancy, the placenta also contributes.
It plays a key role in reproductive development, fat distribution, and bone health. Testing is commonly used to evaluate menstrual irregularities, menopause, ovarian function, and fertility (5).
Progesterone is produced by the ovaries and is especially important in the second half of the menstrual cycle. It prepares the uterus for implantation.
Testing can help assess ovulation, fertility treatment response, and miscarriage risk. Low levels may be associated with symptoms such as mood changes, low libido, heavy periods, and metabolic changes (6).
Testosterone is essential in both men and women. In men, levels below ~300 ng/dL are generally considered low.
It plays a role in muscle mass, bone density, energy, mood, libido, and red blood cell production. Symptoms of low testosterone may include fatigue, increased body fat, decreased libido, and cognitive changes. Diagnosis is confirmed through blood testing (7).
The adrenal glands produce hormones involved in stress response, inflammation, and energy regulation. Dysfunction can lead to fatigue, metabolic issues, and immune dysregulation.
Cortisol, often called the “stress hormone,” plays a role in inflammation control, blood sugar regulation, metabolism, and blood pressure.
Testing can help evaluate adrenal or pituitary disorders such as Cushing’s syndrome or adrenal insufficiency (8).
DHEA-S is an androgen produced by the adrenal glands and serves as a precursor to other sex hormones.
Abnormal levels may contribute to symptoms such as acne, hair changes, menstrual irregularities, or metabolic issues. It is often tested alongside other sex hormones (9).
Metabolic health markers provide insight into insulin sensitivity and glucose regulation—key drivers of chronic disease.
Insulin is produced by the pancreas and allows the body to utilize glucose for energy. It works alongside glucagon to maintain blood sugar balance.
When insulin production is impaired or the body becomes resistant, blood sugar rises, increasing the risk of diabetes (10).
Blood glucose measures circulating sugar levels. Normal targets are typically:
Abnormal levels may indicate prediabetes or diabetes (11).
Hemoglobin A1C reflects average blood glucose levels over the past 2–3 months. It provides a long-term view of glycemic control and is used to diagnose and monitor diabetes (12).
Sex hormone-binding globulin regulates the amount of active (free) testosterone in the body (13).
Luteinizing hormone plays a role in ovulation and testosterone production (14).
Follicle-stimulating hormone is critical for reproductive function and gonadal health (15).
Prolactin supports lactation but can also influence libido, fertility, and menstrual cycles (16).
Reverse T3 is an inactive form of T3 and may increase during stress, illness, or inflammation (17).
Vitamin D supports bone health, immune function, and overall metabolic health (18).
Ferritin reflects iron storage levels and is critical for assessing iron status (19).
Hormone testing provides a deeper understanding of how the body is functioning at a systems level. These insights allow for more precise, personalized, and proactive care—moving beyond symptom management toward true optimization.
