Tired all the time: the tests worth doing, and the ones that are not

"Tired all the time" is common enough in general practice to have its own abbreviation. It is also one of the presentations most likely to be waved away, partly because a cause is found in only about a third to a half of cases. That statistic gets used as a reason not to look. It is a bad reason: when a cause is found it is usually simple, and when it is not found, the exercise of ruling things out is itself worth something.

The history does more work than the bloods

Before any test, there are questions that reliably change the answer. What time do you actually fall asleep, and what time do you actually wake. Do you snore, and has anyone told you that you stop breathing. How much alcohol in a normal week, counted properly rather than estimated. What medication are you on, including the ones you do not think of as medication. And what happened in the six months before this started.

Sleep apnoea, alcohol, medication side effects and depression between them account for a large share of fatigue that never gets a blood test explanation, and none of the four shows up on a panel.

The nine tests worth doing first

1. Full blood count — anaemia, and occasionally something more.
2. Ferritin — iron stores fall long before haemoglobin does. This is the single highest-yield test in tired young women and it is routinely omitted.
3. Thyroid function — TSH and free T4.
4. HbA1c — undiagnosed diabetes and prediabetes.
5. Vitamin B12 and folate.
6. Coeliac screen — only valid while you are still eating gluten, which is why cutting it out before testing is unhelpful.
7. Vitamin D — deficiency is common at this latitude, particularly between October and April.
8. Kidney and liver function.
9. Inflammatory markers where the picture warrants it.

Bought one at a time that is £456. Six of the nine sit inside our Foundation health check at £395, so in practice most people take the Foundation and add vitamin D, B12 and the coeliac screen on top. Either way it finds the great majority of the findable.

The tests I will usually talk you out of

Food intolerance IgG panels. These are sold widely and they do not test what they claim to test. IgG antibodies to food indicate exposure, not intolerance. A positive result reliably leads to an unnecessarily restricted diet.

"Adrenal fatigue" salivary cortisol profiles. Adrenal insufficiency is a real and serious diagnosis with a proper test. "Adrenal fatigue" as a graded syndrome of exhaustion is not a recognised condition and the systematic reviews looking for it have not found it.

Very broad direct-to-consumer panels. Run enough tests on a well person and some will come back marginally outside the reference range purely by chance — the reference range is defined so that a proportion of healthy people fall outside it. Each of those generates worry, a repeat, and sometimes an investigation.

Free T3, routinely. In most cases it does not change management. I add it when there is a specific reason.

More tests on a well person is not more thorough. It is mostly more noise, and noise has a cost.

When tiredness is urgent

Tiredness combined with unexplained weight loss, drenching night sweats, a new lump, bleeding from anywhere, or breathlessness on mild exertion is a different problem and should be seen this week. Say so when you phone and we will find you something.

If everything is normal

Then we have learned something real: this is not anaemia, thyroid disease, diabetes or coeliac. The next conversation is about sleep, mood, alcohol, activity and what has changed in your life — and about whether a sleep study is warranted. That conversation is usually the one that helps, and it needs half an hour, not the last ninety seconds of an appointment.

This article is general information, not advice about your situation. If something here applies to you, book an appointment or speak to your own doctor. Ravelston Health is not an emergency service. If you need urgent help call 999, or NHS 24 on 111 when your GP practice is closed.