Hormone Health Hub: Expert Insights on Testing, Balance & Better Living

Neurotransmitter testing is one of the most powerful functional assessment tools available — but it requires a nuanced approach to interpretation. In this clinical overview, Dr. Kate Placzek of ZRT Laboratory outlines the key fundamentals every practitioner needs before reading a neurotransmitter report: from understanding patterns over numbers and treatment sequencing, to the clinical significance of low serotonin on SSRIs, GABA’s peripheral mechanisms, and when to run a diurnal catecholamine assessment.

If you are experiencing infertility issues, understanding which hormones to test — and why — is the essential first step. Dr. Alison McAllister of ZRT Laboratory explains the full fertility hormone profile: from LH and FSH as indicators of ovarian reserve, to estradiol, progesterone and testosterone for ovulation health, adrenal hormones cortisol and DHEA-S, thyroid markers including TPO antibodies, and the often-overlooked role of vitamin D in fertility and PCOS.

Cortisol is your body’s primary stress hormone, produced by the adrenal glands in response to physical, mental and emotional stress. While it plays a vital role in energy metabolism, immune function and cardiovascular health, both chronically high and chronically low cortisol levels can cause significant health problems — from fatigue, weight gain and sleep disorders to burnout and adrenal exhaustion. This article explains what cortisol is, what happens when it goes wrong, and why regular testing matters.

Reverse T3 (rT3) is one of the most misunderstood markers in thyroid testing. Often called the “hibernation hormone,” it is frequently claimed — without scientific basis — to block thyroid receptors and slow metabolism. In Part 2 of this series, Margaret Groves of ZRT Laboratory examines what the peer-reviewed literature actually says about rT3, when elevated levels are clinically meaningful, and how to interpret the T3/rT3 ratio in the context of a comprehensive thyroid assessment.

Thyroid symptoms can persist even when thyroxine (T4) levels appear normal — because thyroid function is profoundly affected by anything that disrupts the conversion of T4 to the active hormone T3 at the cellular level. In Part 1 of this two-part series, Margaret Groves of ZRT Laboratory explains the three deiodinase enzymes (D1, D2 and D3) that act as gatekeepers to intracellular thyroid hormone bioavailability, what affects circulating levels of T3 and reverse T3, and why selenium, iodine and inflammatory conditions all play a critical role.