“I’m exhausted all the time — can you just test me for everything?”

"Tired all the time" (TATT) is common, real and usually multifactorial, and the strong consultation does TWO things at once: a STRUCTURED history with a red-flag screen and a FOCUSED first-line investigation, AND genuine exploration of the life behind the fatigue. Characterise the tiredness (sleepiness vs lack of energy vs muscle fatigue), its duration, pattern and functional impact, and screen red flags (weight loss, fevers/night sweats, lymphadenopathy, breathlessness, focal/neurological symptoms, bleeding, a progressive course) whose presence redirects to urgent investigation. Resist the scattergun "test for everything": a reasonable evidence-based panel is FBC (very urgently, within 48 hours — NICE NG12 (Suspected cancer: recognition and referral, last updated April 2026) advises considering this for persistent fatigue), ferritin, TFTs, HbA1c/glucose, U&E, LFTs, calcium, CRP/ESR and coeliac serology (NG20: only while eating gluten in more than one meal a day for at least 6 weeks), with vitamin D, B12/folate, pregnancy test or HIV added per history — explained, because indiscriminate testing breeds false positives, incidental findings and anxiety. Equally, explore the commonest causes — depression and anxiety, poor sleep, work/relationship/financial stress, alcohol/caffeine, diet and activity, and life events — openly and without judgement, often using "what are you most worried it might be?" and "what’s life like at the moment?" to surface the real driver (a fear, or an unnamed stressor or unrecognised depression). Avoid both errors: over-investigation feeds health anxiety, while prematurely labelling "just stress" risks missing organic disease or invalidating distress — so hold organic and psychosocial possibilities together as complementary, offer proportionate lifestyle/mood support alongside the screen, safety-net for evolving red flags, and arrange a definite review. There is no suspected cancer pathway referral for undifferentiated fatigue without red flags, but NICE NG12 does advise considering a very urgent FBC (within 48 hours) for persistent fatigue, and red-flag safety-netting completes it. If post-exertional malaise persists, NICE NG206: suspect ME/CFS in adults when the key symptoms, including post-exertional malaise, have lasted at least 6 weeks; diagnose only if they persist for 3 months and are not explained by another condition.