In a 15-minute routine check-up, there is barely enough time to measure blood pressure and review lab results. There is certainly not enough time for a physician to ask the specific follow-up questions that distinguish "probably nothing" from "this needs investigating." Here are the symptoms that most commonly fall through the cracks — and why a thorough clinical history matters as much as any blood test.
Unintentional weight change
Losing more than 5% of body weight over 6–12 months without trying is clinically significant; marked unexplained weight gain also deserves a closer look. Unintentional weight loss can signal cancer (particularly gastrointestinal, lung or hematologic malignancies), hyperthyroidism, diabetes or depression. Unintentional weight gain can indicate hypothyroidism, Cushing's syndrome or metabolic dysfunction. In a rushed visit, the question often isn't asked — or the answer is attributed to "stress" without further investigation.
Night sweats
Waking up drenched — not just warm, but having to change your shirt or sheets — is not normal. Causes include lymphoma (classically), infections (including tuberculosis), endocrine disorders and medications. Most causes are benign (perimenopause in women, for instance), but a careful history can pick out the pattern that should prompt further tests: drenching sweats together with unexplained fever above 38 °C or weight loss of more than 10% within six months (the "B symptoms" of lymphoma).
Changes in bowel habits
A persistent change lasting more than 3 weeks — new constipation, new diarrhea, narrower stools or blood in the stool — warrants investigation. This is one of the most common early symptoms of colorectal cancer, and it is routinely dismissed as "probably IBS" or "dietary" without further work-up. A structured review of symptoms should ask about bowel habits explicitly, with specific follow-up questions about duration, blood and associated symptoms (see also why colonoscopy saves lives).
Persistent fatigue
Everyone is tired. That is the problem — fatigue is so universal that it is almost never investigated properly. But persistent, unexplained fatigue (more than 4 weeks, not improving with rest) can indicate anemia, thyroid dysfunction, diabetes, sleep apnea, depression, chronic infection or — rarely but importantly — malignancy. Basic blood tests cover the most common causes (complete blood count for anemia, TSH for thyroid, HbA1c and HOMA-IR for metabolic dysfunction, ferritin and B12 for nutritional deficiency), and a short questionnaire such as STOP-Bang flags sleep apnea risk.
New or changing moles
Most people have between 10 and 40 moles. A new mole after age 40, or any mole that changes in size, shape, color or sensation, warrants dermatoscopic examination. This is melanoma's primary warning sign — and, as with many cancers, the stage at detection strongly determines the outcome: caught early, melanoma is highly treatable. A full-body examination with a dermatoscope catches what self-examination and naked-eye checks miss (see skin cancer and dermatoscopy).
Persistent hoarseness
Hoarseness lasting more than 3 weeks that isn't explained by a cold or voice overuse can indicate laryngeal cancer, thyroid pathology or vocal cord paralysis (which itself can be caused by lung cancer compressing the recurrent laryngeal nerve). It is easily dismissed. It shouldn't be.
Why the clinical history matters
Blood tests and imaging are powerful tools. But the single most important diagnostic instrument in medicine is still a careful clinical history — taken by a physician who has enough time to listen, ask follow-up questions and connect symptoms that might seem unrelated. If you have any of the symptoms above, say so explicitly at the start of your appointment, note when it began and how it has changed, and ask for a longer slot if needed. A real conversation, not a checkbox exercise.
References
- Hamilton W. Cancer diagnosis in primary care. Br J Gen Pract. 2010;60(571):121-128.
- NICE. Suspected cancer: recognition and referral. NICE guideline NG12. Recommendations last updated 2026.
This article is general information and not individual medical advice. Decisions about tests and treatment belong in a conversation with your own physician.