Hormones 101 (The Great, Big, Web of Connections)

Have you ever wondered why stress can make you miss your period, or why you’re totally exhausted after busy seasons at work? Well, you can thank your hypothalamic-pituitary-adrenal-thyroid-gonadal axis for those things, along with quite a few of the other physiological phenomena we experience in this life.

Okay, okay, hypothalamo-whatta-whatta?

If that’s what you’re thinking, you’re in good company. That’s what I said, the first time I learned about the hypothalamic-pituitary-adrenal-thyroid-gonadal axis. Basically, what that phrase refers to is the fact that a part of our brain called the hypothalamus communicates with our adrenal glands, thyroid, and ovaries (aka gonads) through a series of hormones produced by the pituitary gland (also located in our brain). In physiology, we often talk about those interactions separately, referring to them as the hypothalamic-pituitary-adrenal axis, or the hypothalamic-pituitary-thyroid axis. But in reality, they’re all connected, and this post will explain everything you ever wanted to know about how and why. (Okay, maybe not everything, but the basics…)

The HPATG Axis (AKA Endocrine Axis)

HPATG physiology can basically be summed up like this: the hypothalamus talks to our pituitary gland using hormonal signals, telling the pituitary gland when and how to stimulate our thyroid, our adrenal glands, and our ovaries. All of those glands send hormonal messages back to our brain with information about how much activity is going on, and whether or not there are any problems. In response, the brain tells the body to amp up activity in each of those sites, or tone it down. This is called a negative feedback loop.

HypothalamusPituitaryOrganFunction
ThyroidThyrotropin Releasing Hormone (TRH)Thyroid Stimulating Hormone (TSH)Thyroid Hormones (T3, T4)Metabolism
Gonads (Ovaries)Gonadotropin Releasing Hormone (GnRH)Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH)Estrogen and ProgesteroneFertility
AdrenalCorticotropin Releasing Hormone (CRH)Adrenocorticotropic Hormone (ACTH)CortisolMetabolism & Stress Response

When we face periods of stress (or rather, when we face too much stress for too long), our HPATG axis is completely intercepted. This is where we can run into imbalances in our thyroid hormones (such as hyperthyroidism or hypothyroidism), adrenal hormones (such as “adrenal fatigue“), or fertility problems, (such as hypothalamic amenorrhea). These problems can occur one at a time, or all at once, leading someone to feel really sick, and probably also really confused! Stress is a biggie when it comes to a properly functioning HPATG axis.

Stress and Stress Management

When we think about stress, we typically think about the psychological or emotional—deadlines at work, an overly packed schedule, a bad breakup, or a death in the family. But stress comes in many forms, and can even be triggered by good life events…

  • Under eating (not enough calories or carbs)
  • Nutritional deficiencies
  • A significant/sudden change in diet/eating habits (especially yo-yo dieting)
  • Over exercising (or a sudden change in the type of exercise)
  • Lack of sleep or change in sleep schedule (i.e. night shift)
  • Illness or injury (including surgery)
  • Travel (even if it’s fun!)
  • Moving
  • Starting a new job or educational program
  • Getting married
  • Certain medications, or drug use
  • Depression or anxiety
  • Emotional distress (like the loss of a loved one)
  • Psychological distress (like deadlines or studying)

Many of these things are normal parts of life, and when we are following a pattern of self care, our bodies are able to accommodate the stressors without falling into dysfunction. But when our self-care routine falls out of balance (or we begin struggling with disordered eating) we detract from the foundation of health. When that happens, everything else starts to crumble. One of my favorite ways to explain this relationship between stress and self-care is the bucket analogy:

Self-care fills our bucket, but stress drains our resources. When the bucket gets low, we start to notice symptoms of burnout. When the bucket gets empty, it leads to hormonal disaster, interrupting our whole HPATG axis at a biochemical level in our brains (big red stress arrow on the infographic at the top of this post).

Dysfunction, one axis at a time

The reason we often talk about the HPATG axis in terms of its separate components (HPA, HPT, HPG axes) is because unilateral dysfunction is common. For example, an autoimmune disease called Hashimoto’s Thyroiditis can lead to destruction of the tissue of the thyroid gland and subsequent hypothyroidism. When this happens, the thyroid loses its ability to produce thyroid hormone. When the pituitary gland realizes that thyroid hormone levels are so low, it amps up its secretion of thyroid-stimulating hormone in an attempt to tell the thyroid to do a better job. The problem is, the thyroid itself has been damaged—it can’t do its job until the autoimmune reaction is addressed.

Low levels of thyroid hormone create a stress response in the body, signaling back to the brain that something’s off. This consequently affects the signaling between the pituitary gland and the adrenals/ovaries as the body tries to balance things out. Low levels of thyroid hormone, for example, creates a dangerous environment for a growing baby, and so the reproductive system is one of the first to get shut down (via the HPATG axis). On the other hand, pregnancy causes the body to re-prioritize its hormonal resources. When a woman is pregnant, the body needs different levels of thyroid hormone, cortisol, and other hormones to carry the pregnancy to full-term. These body signals these changes through the same negative feedback loop. (All of this takes place without us ever having to think about it. You’ve got to admit, God’s design is pretty amazing!)

The HPATG Axis and Healthcare

When a patient complains of problems like fatigue, weight gain or weight loss, thinning hair, or irregular periods (just to name a few), the solution is never as simple as writing a prescription for birth control pills or Synthroid. There’s always more to the story, and that’s why its so important to identify the root cause of the problem by talking with the patient in detail about their health history, and taking a closer look at the lab work. From a functional medicine perspective, it’s never safe to assume that the other components of the HPATG axis are functioning properly, even if we’ve already identified that one of them is out of sync. That’s why holistic healthcare means addressing the whole person, and not just using a symptom-by-symptom, band-aid approach.


If you’re struggling with your health—whether in terms of diet recovery, fertility, thyroid health, adrenal fatigue, or something else—send me an email or fill out a contact form. I work with women with these concerns through all the time, and I’d love to help you, too.


11 thoughts on “Hormones 101 (The Great, Big, Web of Connections)

  1. Pingback: PCOS, Explained

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