wieviel stuhl für stuhlprobe — when to see a doctor?

The question about how much stool is needed for a stool sample and when to see a doctor cannot be answered from the provided context, which focuses on DNA tests and blood biomarkers. In general medical practice: a stool sample typically requires about 5–10 g (pea- to walnut-sized). For fecal immunochemical tests (FIT) for colorectal cancer screening, two small samples are often sufficient; for stool culture or calprotectin measurement, a larger amount may be needed. The sample must not be contaminated with urine or toilet water. When to see a doctor: persistent diarrhea (>3 days), blood in stool, unexplained weight loss, severe abdominal pain, fever, or changes in bowel habits (e.g., alternating constipation and diarrhea). Also seek medical advice if you have risk factors such as family history of colorectal cancer or inflammatory bowel disease. Evidence level: practice (clinical guidelines). Safety note: collect stool hygienically and deliver promptly (refrigerate if needed). The provided context does not contain relevant sources for this topic.