The Body in the Room: Why Physical Causes Deserve a Hearing Before 'It's Just Anxiety'

Consider a sequence that plays out in GP surgeries every week. A person in their thirties describes palpitations, broken sleep, a churning stomach, irritability and difficulty concentrating. The consultation is ten minutes long. The picture is coherent, the waiting list for talking therapy is long, and a diagnosis of anxiety is recorded. It may well be right. It may also be the point at which the investigation stops.

This is not an argument for suspicion, and it is certainly not an argument against the diagnosis of anxiety, which is common, disabling and genuinely treatable. It is an argument about sequence. Symptoms are not labelled. Palpitations, fatigue, tremor, sweating, breathlessness, low mood and poor concentration are produced by the mind and the body with equal enthusiasm, and the two are not in competition.

Where the overlap actually lies

NICE guidance on generalised anxiety disorder and on depression both ask clinicians to consider physical causes and substance effects before settling. That is not a formality. Thyroid disease, anaemia, sleep apnoea and perimenopause are all common, all capable of producing a convincing psychiatric picture, and all treatable once identified.

The reverse is also true, and worth saying: living with an undiagnosed physical illness is anxiety-provoking, and chronic physical illness raises the risk of depression. The relationship runs in both directions, which is why a single label rarely captures the whole of it.

The checks that earn their place

Thyroid function. An overactive thyroid produces weight loss, heat intolerance, tremor, a racing heart and irritability; an underactive one produces fatigue, slowed thinking and low mood. A TSH test is cheap, and free T4 follows if the TSH is abnormal. This is the best-established example of a physical mimic in primary care.

Full blood count and ferritin. Iron deficiency causes fatigue, breathlessness on the stairs, headaches and restless legs, with or without frank anaemia. Ferritin is worth measuring where there is fatigue and a plausible cause — heavy periods, a vegetarian diet, long-term anti-inflammatory use — though it rises with inflammation and is not a straightforward number.

HbA1c. Both undiagnosed diabetes and the hypoglycaemic episodes of treated diabetes can generate sweating, tremor and a sense of dread that closely resembles panic.

Vitamin B12 and folate. Fatigue, cognitive fog, pins and needles and low mood. Worth checking in people who take metformin or long-term acid-suppressing medication, and in those on a vegan diet.

A sleep study, where the pattern fits. Obstructive sleep apnoea is under-recognised. Loud snoring, witnessed pauses in breathing, morning headaches, unrefreshing sleep and daytime sleepiness in someone with a raised BMI should prompt an Epworth Sleepiness Scale score and, if suggestive, referral. Treating apnoea sometimes transforms mood in ways no antidepressant achieved.

Perimenopause. In women over 45, the diagnosis is clinical rather than biochemical; NICE advises against relying on FSH levels, which fluctuate. That does not make the mood, sleep and palpitation symptoms any less real, and a conversation about hormone replacement therapy belongs in the room alongside a conversation about SSRIs.

Cardiac and autonomic causes. Palpitations with breathlessness or dizziness warrant examination, an ECG and, where the history is episodic, ambulatory monitoring. Postural dizziness on standing is worth a lying-and-standing blood pressure reading.

The everyday culprits. Caffeine deserves its reputation; so do alcohol, decongestants, steroids and some asthma inhalers. A two-week symptom and substance diary is often more informative than a blood test.

What the evidence does not support

Routine screening of everyone with low mood is not recommended, and a scattergun approach has real costs: incidental findings that lead to further tests, waiting lists and worry, and false reassurance when a normal panel is taken to mean nothing physical is wrong.

Private 'full body MOTs' and commercial hormone panels are a poor use of money here. Vitamin D testing is not a mood test. Testing is only useful when the result would change what happens next.

Making the case without turning it into a campaign

Three practices help. First, write down the three symptoms that worry you most, with dates and what makes them better or worse. A short written list outperforms a long verbal account in a ten-minute appointment. Second, ask a direct question: 'What is your working diagnosis, and what would make you reconsider it?' That invites reasoning rather than a standoff. Third, ask when to expect review — four to six weeks is a reasonable interval for someone who is not improving on treatment.

If you are offered a blood test, ask what is being checked and how you will be told the result. Results are generally visible in the NHS App, and it is entirely reasonable to read them before the follow-up.

Symptoms that should override any label

Unexplained weight loss, night sweats, new focal weakness or numbness, abnormal bleeding, chest pain on exertion, fainting, a resting heart rate persistently above 100, or repeated infections all deserve assessment on their own terms, whatever has been written in the notes already.

A closing thought

'It's just anxiety' is sometimes a completely accurate summary of a difficult problem. It is also sometimes a placeholder — the thing said when the appointment is ending and the picture is incomplete. The difference between the two is rarely a matter of more tests. It is usually a matter of someone taking a fuller history, examining the patient, and leaving the question open long enough for the body to answer.