Before You Consider Antidepressants, Anti-Anxiety medication or a Neurodiversity Assessment, Get Your Blood Checked (Hear me out…)

If you have been experiencing low mood, fatigue, anxiety, brain fog, difficulty concentrating, or a general sense that something is not right, you may be beginning to wonder whether antidepressants or a neurodiversity assessment might be the answer (and they may well be). There is an additional step worth considering - getting a blood test – a full blood count (including a thyroid function test) and maybe a check of your Ferritin (iron levels) to be specific.

This is absolutely not a reason to dismiss what you are experiencing, or to delay getting support. It is practical advice, because several common and entirely treatable physical conditions produce symptoms that are almost indistinguishable from depression, anxiety, and a range of cognitive difficulties associated with ADHD or autism. Missing them can lead to people being medicated or assessed for conditions that they may not have, while the actual cause goes unaddressed.

 

Thyroid function

The thyroid gland regulates metabolism, energy, mood, and cognitive function. When it is underactive (hypothyroidism) the symptoms can include persistent fatigue, low mood, weight gain, brain fog, slow thinking, poor memory, and a general flatness that is very difficult to distinguish from depression. When the thyroid is overactive (hyperthyroidism) it can produce anxiety, restlessness, difficulty concentrating, sleep disruption, and racing thoughts.

Thyroid conditions are extremely common, particularly in women, and they are straightforwardly diagnosed through a blood test. They are also extremely treatable. Someone whose low mood is driven by an underactive thyroid will not be helped by antidepressants in the way that someone with a depressive disorder would be.

 

Vitamin D

Vitamin D deficiency is remarkably prevalent in the UK, where sunlight is limited for much of the year. Low vitamin D is associated with low mood, fatigue, poor concentration, and a reduced sense of wellbeing. The relationship is not fully understood, but the association is consistent enough that deficiency is worth ruling out before pursuing other explanations for these symptoms. A simple blood test will establish your levels. Supplementation is relatively inexpensive and, for many people, makes a noticeable difference.

 

B12 and folate

B12 deficiency can produce fatigue, low mood, difficulty concentrating, memory problems, and in more severe cases, neurological symptoms. It is more common in people who follow a vegan or vegetarian diet, in older adults, and in people with certain digestive conditions that can affect absorption. Folate deficiency produces a similar picture. Both are diagnosed through a standard blood test and come with clear treatment protocols.

 

Ferritin and iron

Iron deficiency (even without full anaemia) can produce significant fatigue, poor concentration, low mood, and a general sense of depletion that is easy to mistake for depression or burnout. Ferritin is the stored form of iron and is the more sensitive biomarker; a normal haemoglobin result does not necessarily rule out low ferritin. If you are experiencing any of these symptoms it is worth asking your GP to check ferritin specifically, rather than relying on a standard full blood count alone.

 

Oestrogen

For women in perimenopause or menopause, fluctuating and declining oestrogen can produce anxiety, low mood, sleep disruption, and cognitive difficulties that are frequently mistaken for mental health conditions. FSH levels can help indicate where someone is in the menopausal transition, though they are not definitive. Your self-reported experience can be the most accurate route for diagnosis. A conversation with a GP about your hormonal status is worth having before attributing these symptoms exclusively to anxiety or depression.

 

What to ask for

A standard GP blood test will often cover thyroid function, full blood count, and B12. You may need to ask specifically for ferritin, vitamin D, and folate as they are not always included as a matter of course. If you are a woman in your thirties, forties or fifties and experiencing mood or cognitive changes, it is worth having a conversation about perimenopause symptoms (and perhaps exploring hormone testing too).

None of the above replaces mental health support, and physical and psychological causes can both be present at once. But starting with a clear physical picture is good practice, and it ensures that your next steps are based on the most accurate understanding of what is happening for you.

If you have already ruled out physical causes and are looking for therapy support, you are welcome to get in touch.

Dr Erin Reid is a counselling psychologist offering online therapy to individuals, couples, adolescents, and families across the UK and internationally, and 'Walk and Talk' therapy in Northwest London green spaces. Visit drerinreid.com to find out more.