Blood tests for depression that can be useful to investigate root causes

blood tests for depression

The essential blood tests for depression

In this solo episode, I talk about the essential blood tests to run if you are suffering from depression. The absolute must-test markers that will give you a great insight into what is going on within your body. 

Depression is not in your head and is instead deeply linked to your physical health. So listen to this episode to find out what blood markers I check for with my clients. 

If you are interested in becoming a client and working with me to really transform your mental health, then book a free call with me here.

Read the transcript here

Hello all, and welcome back to a solo episode. This time I’m talking about blood tests that can be really useful to run if you are suffering from depression and want to 

a) get a better understanding of WHY you are struggling with your mental health and 

b) if you want to get better.

So I’m a nutritional therapist and have learned quite a bit now about the various tests you can do, whether that’s stool testing, urine testing or blood testing to investigate what is going on with your health. One thing I do want to say is that this whole field of holistic health, or integrative medicine, lifestyle medicine, functional medicine – whatever you want to call it – keeps on evolving. 

We keep on learning more and more about the root causes of ill health, including depression and anxiety, and we also learn more about more about optimum health, and how to get there. New tests are constantly being developed, and there really are many different paths you can take if you want to go into lab testing.

And one thing I particularly want to point out is this: You NEED to move away from focusing entirely on your mood and mental health and trying to figure out what is wrong with those. Instead, you need to focus on your ENTIRE health. Good mental health is reliant on good brain health. And your brain is very much part of your physical body, and very much influenced by everything that is going on THROUGHOUT this body of yours. 

And that is why, for example, I’ve run stool tests with my clients before – even though they primarily come to see me for their mental health problems, and not their digestive issues. Their gut health, in this instance, had a huge impact on their entire health, including their brain health, so including their mental health.

So when you hear terms such as functional medicine, it’s really about this wide lens approach: Moving away from focusing on particular organs and problems, and instead thinking about the systems in your body. 

Where are the imbalances in your body? And why do they express themselves as xyz symptom, such as depression and anxiety? Because that’s what depression and anxiety are: they are symptoms. Symptoms of underlying imbalances. Depression is not the root cause of your problem – it’s a symptom of an underlying need that isn’t being met.

I hope that’s clear. Back when I was suffering from depression, I thought that depression was the illness and it meant that something was wrong with my mind or my character. Or that my neurotransmitters were out of balance and that I needed medication.

But when I started seeing depression as a symptom of something deeper that needing addressing, things just really started to make so much more sense.

So with this in mind, what blood tests can you run that will help shine a light on some of these potential underlying root causes of depression?

  1. A full thyroid panel

Your thyroid is a gland that is very small, it’s shaped like a butterfly and sits just in front of your windpipe in your neck. It produces hormones that control lots of functions within your body, primarily affecting your metabolism. And sometimes the thyroid struggles to produce enough thyroid hormones and that can end up in a condition called hypothyroidism, which is actually relatively common in women. What are the symptoms of hypothyroidism, so when your thyroid doesn’t produce enough thyroid hormones?

Tiredness, depression, slow movements and slow thinking, loss of your sex drive, irregular or heavy periods, weight gain, getting cold easily, constipation and more. A lot of these symptoms overlap with how women often feel and what they experience when they’re struggling with depression.

So ruling out low thyroid hormone output can be really quite important when you’ve been battling with depression.

GPs and doctors often run thyroid tests but tend to test only certain markers which don’t necessarily give you the full picture. So ideally what you’d test are your thyroid stimulating hormone, your thyroxine free T4  and free T3 levels and thyroid antibodies. This test is really easy to do and doesn’t cost you the earth either.

  1. Haemoglobin A1C or HbA1C

If you are struggling with diabetes, you will probably know of this marker. Testing this marker is about testing your blood sugar control, so how well your body handles the sugar that comes from the breakdown of your carbohydrates. If you don’t know what I’m talking about, I’d really encourage you to listen to episode 5 of my podcast titled “Depression and anxiety and the incredible link to blood sugar imbalances”.

So HbA1C gives you an average of your blood sugar levels over the past 2 to 3 months. And higher HbA1C levels are associated with increased depression symptoms, so it’s a valuable and easy marker to look at – particularly because you can easily make changes in terms of your diet and lifestyle to bring your levels down to an optimum amount – if it is elevated.

  1. High-sensitive C-Reactive Protein (hsCRP)

Now because depression can be linked to chronic inflammation (see episode 3 of this podcast), it can be really helpful to measure hsCRP levels. It’s a protein that your liver makes when there are general inflammatory messengers in the body, and ideally your levels are within a certain range.  A higher level is associated with more severe depression, but it’s good to have this double checked. If it is high, you want then obviously want to look at the source of the inflammation.

  1. Homocysteine

Homocysteine is an amino acid that when elevated can indicate inflammation, plus potential deficiencies of folate, vitamin B12 and B6 – all of which are linked to depression.

  1. Vitamin B 12

And speaking of which, it can be useful to measure vitamin B12 levels in your blood. This is a very common deficiency and it’s fairly easy to eat a diet that is low in B12, particularly if you eat a vegetarian and especially a vegan diet. Poor gut health is also linked to low B12 but anyway!

  1. Vitamin D

Vitamin D has been in the spotlight recently with regards to Covid! So vitamin D is actually a hormone that we all know gets produced when your skin is exposed to sunlight, particularly in the brighter months of the year (but that can still not be enough up in the northern hemisphere). You can also get vitamin D through the diet. Deficiency of this vitamin is very common, and it’s also associated with poor mental health outcomes. Again, a very easy and relatively inexpensive test.

  1. Ferritin

Ferritin put simply, is a protein in your blood but also in other areas such as your liver that contains iron, so by testing your ferritin levels you get to understand how much iron your body stores. And knowing your ferritin and iron levels when you’re suffering from depression can be really helpful. Why? Because you don’t want to be thinking that there is something seriously wrong with your health and your energy levels when in fact you are iron deficient and anaemic, which again is something that can easily be corrected.


So that’s the basic blood markers, which as I’ve just said, I have run as one test by an independent lab, that offer a really good insight into your health. They help rule out some of the potential underlying conditions and address common nutritional deficiencies in depression. It’s a fantastic starting point and once you address what’s come up in the results with lifestyle changes and supplements or remedies, much more is often not needed.

If budget allows, testing your essential fatty acids levels, particularly your omega 3 fatty acid levels, can also be extremely valuable.

But just to say, in some cases it can also be helpful to take a deep dive into your hormone production or your gut health for example, but I tend to only do that if your symptoms persist after our initial work. You can run tests to check for chronic infections, toxic overload, mould exposure, food intolerances and much more. And these can all be fantastic tools, but you always need to start with the fundamental basics.

Ever since specialising in holistic mental health, I’ve really realised that it’s about the balance in life. And the information you’d get from testing these 8 markers is really useful and form a good solid base for your mental health journey. Plus, in my work with clients I spend 2 hours initially in our first consultation together to really get to know them and their health and bodies. And that’s on top of a 11 page health questionnaire that I have all of my clients fill in before we meet. So that’s a lot of information to get started with!

So I hope this dive into blood markers has been useful. If you want to find out more about my the way I work with my clients then get in touch via email or go ahead and choose a suitable time to have a quick Zoom call that I offer for free. We can then discuss whether my approach and my programme are what will help you get to better mental health. 

That’s all from me today. I will be back with another episode all about holistic approaches for good mental and brain health soon.

Welcome to my podcast

I’m Claudia Smith, a qualified nutritional therapist, functional medicine practitioner and coach specialising in depression. This is where I share my thoughts and advice on natural and holistic approaches to overcoming depression.

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