Adrenal fatigue or thyroid dysfunction? How to tell the difference
Do you feel exhausted no matter how much you sleep, struggle to think clearly, feel cold all the time and find it harder than ever to manage your weight? These symptoms are incredibly common in women in their 40s, and they could be pointing to your adrenals, your thyroid or both.
Both adrenal fatigue and thyroid dysfunction involve the endocrine system and affect hormone regulation, which is why there is so much overlap between symptoms. Both conditions are also more common during perimenopause, and unfortunately are often missed on standard blood tests, leaving many women in the frustrating situation of being told “everything is fine, your results are normal”, despite having clear symptoms.
What is adrenal fatigue?
The term 'adrenal fatigue' is widely used in functional and integrative medicine to describe a state where the adrenal glands are under-functioning as a result of prolonged stress. In research circles, 'HPA axis dysfunction' is increasingly preferred as it more accurately describes what is actually happening - a disruption to the communication between the hypothalamus, pituitary gland and adrenal glands, rather than the glands themselves simply being fatigued. Neither term is recognised as a formal diagnosis in conventional medicine, which can be incredibly frustrating for women who are clearly experiencing something real.
The adrenal glands are responsible for producing stress hormones, primarily cortisol and adrenaline. In a healthy stress response, cortisol rises when the body encounters a stressor and then returns to normal, but in situations where a person has been experiencing high levels of stress for long periods of time, the adrenal glands struggle to respond appropriately.
In the early stages of adrenal fatigue, cortisol is elevated more often than it should be. This is sometimes referred to as the “wired but tired” phase, where women feel exhausted but can’t switch off or sleep well. Over time, if the stress continues, cortisol output can drop below normal, leading to the depleted phase where even getting out of bed feels like a huge effort. Because cortisol follows a natural daily rhythm - highest in the morning and lowest at night - disruption to this pattern explains why so many women with adrenal fatigue struggle most in the morning, crash in the afternoon and find it hard to wind down at night, despite feeling exhausted.
What is thyroid dysfunction and why is it often missed?
When a woman comes to me feeling exhausted, flat and struggling with her weight, the thyroid is the first thing I think about. Not because it's always the answer, but because it's so often missed and therefore worth investigating early.
The thyroid is a small butterfly-shaped gland in the neck that produces hormones responsible for regulating metabolism, energy production, body temperature, heart rate, digestion and mood. The two main thyroid hormones are T4 (thyroxine) and T3 (triiodothyronine) - T4 is the inactive form that needs to be converted to the active T3, and this conversion happens largely in the gut and liver.
Hypothyroidism (underactive thyroid) is the most common form of thyroid dysfunction and this occurs when the thyroid isn't producing enough hormones. Symptoms of hypothyroidism develop slowly and are often subtle in the early stages, which is one reason they're frequently dismissed or attributed to other causes like stress, ageing or perimenopause. Hashimoto's thyroiditis, an autoimmune condition, is the leading cause of hypothyroidism.
The standard test used in conventional medicine is TSH (thyroid stimulating hormone), but TSH alone can appear normal even when a person has clear symptoms. In my practice, I generally refer clients for a comprehensive thyroid panel (TSH, free T4, free T3 and thyroid antibodies), but in Australia this often means going private, as Medicare typically only rebates TSH testing unless the result is abnormal. For women who have been told everything is fine despite ongoing symptoms, it can be a worthwhile investment. Thyroid antibodies are particularly important to test for as they can be elevated for years before TSH becomes abnormal, meaning many women are in the early stages of Hashimoto's without knowing it.
Key differences in symptoms
Keep in mind that there is significant overlap between the two conditions and this list is intended as a guide rather than a diagnostic tool. Many women will experience symptoms in both lists.
Symptoms more specific to adrenal fatigue
Fatigue that is worst in the morning and improves slightly as the day goes on, with a noticeable crash around 3-4pm
Wired but tired - difficulty switching off or falling asleep despite feeling exhausted
Salt cravings - the adrenal glands regulate sodium and potassium balance, so cravings for salty foods are a classic sign
Feeling worse when meals are skipped or delayed - blood sugar dysregulation is closely tied to adrenal function
Symptoms that fluctuate noticeably with stress levels - better during low stress periods, worse during demanding times
Dizziness when standing up quickly (orthostatic hypotension) - related to adrenal regulation of blood pressure
Intolerance to cold or heat
Low blood pressure
Feeling overwhelmed, anxious or unable to cope with things that wouldn't normally bother you
Symptoms more specific to thyroid dysfunction
Weight gain that is unexplained and doesn't respond to changes in diet or exercise
Feeling cold all the time, particularly cold hands and feet
Hair thinning or loss, including loss of the outer third of the eyebrows
Constipation (slow transit time) - persistent and doesn't improve with dietary changes
Puffy face, particularly in the morning
Low heart rate
Dry skin and brittle nails
Symptoms that are consistent and don't improve during low stress periods
Depression (feeling flat and low rather than anxious)
Supporting adrenal function through nutrition and lifestyle
There is no quick fix for adrenal fatigue, but there are many things you can do to support recovery through nutrition and lifestyle.
Regular meals to stabilise blood sugar and support healthy cortisol rhythm - including eating breakfast within an hour of waking
Key nutrients: vitamin C, B vitamins, magnesium and zinc
Prioritise sleep - sleep is when the adrenal glands do the majority of their repair and recovery work
Reduce caffeine, particularly in the afternoon
Avoid intense exercise during the recovery phase - high intensity exercise raises cortisol, which is counterproductive when the adrenals are already under stress. Gentle movement like walking, yoga and pilates are better choices
Address the underlying stress load where possible - nutritional support alone won't fully resolve adrenal fatigue if the stressors driving it haven't been addressed
Reduce alcohol intake, as it disrupts cortisol rhythm and places additional load on the adrenal glands
Ensure adequate protein and healthy fat at each meal to prevent blood sugar spikes and crashes that stress the adrenal glands
Prioritise activities that restore the nervous system, for example, time in nature, creative activities or social connection
Reduce screen time in the evening as blue light suppresses melatonin and disrupts the cortisol rhythm
Supporting thyroid function through nutrition and lifestyle
Nutrition and lifestyle strategies won't replace medical treatment where it's needed, but they can make a significant difference, particularly in the early stages or where nutrient deficiencies are a contributing factor.
Key nutrients: iodine, selenium, zinc, iron, tyrosine, vitamin D, vitamin A and adequate protein. Many women are low in these nutrients and they are common drivers of poor thyroid function. Selenium is particularly important for the conversion of T4 to T3 and also helps protect the thyroid gland from oxidative damage. Brazil nuts are one of the richest food sources of selenium - just 2-3 per day provides a therapeutic amount
Support gut health - a healthy gut plays an important role in thyroid hormone activation
Avoid eating raw cruciferous vegetables in large amounts as they can interfere with iodine uptake. Cooking them reduces this effect significantly
Manage stress, as chronic cortisol elevation can suppress thyroid function
Avoid highly processed foods and environmental toxins like fluoride and chlorine which can interfere with iodine absorption
Blood sugar regulation matters for thyroid function too, so regular meals and limiting refined carbs is relevant here as well
Gluten sensitivity or coeliac disease is strongly associated with thyroid dysfunction, particularly Hashimoto's, so a gluten free trial is sometimes worth considering
Prioritise sleep, as thyroid hormone production follows a circadian rhythm and is affected by sleep deprivation
Avoid large amounts of soy, as it can interfere with thyroid hormone absorption, particularly for people already on thyroid medication
Avoid plastic food containers and choose glass or stainless steel where possible, as endocrine disrupting chemicals like BPA can interfere with thyroid hormone function
When to ask for testing - and what to ask for
Testing is worth considering if you have persistent symptoms that aren't explained by other factors, if you have a family history of thyroid disease or autoimmune conditions, if your symptoms have worsened during perimenopause or following a period of prolonged stress, or if you've already had basic blood tests that came back normal but still feel unwell.
For adrenal function, a single blood cortisol test is available through Medicare but it only measures cortisol at one point in time, which gives a very limited picture. The DUTCH test (Dried Urine Test for Comprehensive Hormones) or EndoMAP panel are much more comprehensive options, measuring cortisol patterns across the day alongside other key hormones. DHEA-S levels are also worth checking, as DHEA is another adrenal hormone that tends to decline with prolonged stress and is associated with fatigue, low mood and poor stress resilience.
For thyroid function, I recommend requesting a full panel rather than TSH alone:
TSH, free T3, free T4 and reverse T3
Thyroid antibodies (TPO and TgAb)
Nutrient levels including iron studies, ferritin, selenium, zinc, iodine and vitamin D
As mentioned earlier, a full panel often needs to be requested privately in Australia as Medicare typically only rebates TSH. Results should always be interpreted in the context of your symptoms and compared with optimal rather than standard reference ranges - this is where working with a practitioner who takes a functional approach can make a real difference.
If you'd like help working out whether your adrenals, your thyroid or both might need some attention, this is exactly the kind of work I do with clients and I’d love to support you. You can find out more at www.nourishtothrive.com.au
References
BioMedica Nutraceuticals (n.d.), Hypothyroidism - Prescribers Guide, BioMedica Nutraceuticals, Australia.
BioMedica (n.d.), HPA axis dysfunction - integrated adrenal health support guide, BioMedica Nutraceuticals, Australia.
Bio-Practica (2012), Thyroid and adrenal assessment chart, Bio-Practica, South Australia.
Eagle Clinical (2004), Understanding hypothyroidism, Eagle Natural Health, Australia.
Eagle Clinical (2013), The importance of adrenal and thyroid health, Eagle Natural Health, Australia.
V. Education (n.d.), Hypothyroidism patient handout, Vital.ly, Australia.