Imagine doing a simple finger test that could alert you to serious health risks like lung cancer or heart disease.

Doctors recommend the Schamroth window test—a quick, non-invasive check. To do it, press the tips of your index fingers and thumbs together. You should see a small diamond-shaped gap between your nails.

If that gap is missing, it might indicate finger clubbing, a symptom linked to several serious conditions. Experts say clubbing can signal underlying problems like lung cancer, heart disease, or gastrointestinal disorders.

Other warning signs include shiny skin near the nails, spongy nail beds, or nails that curve downward. These subtle changes might be your body’s way of sounding an alarm.

While not a diagnosis on its own, the Schamroth test is a useful first step. If you notice abnormalities, it’s worth speaking with your doctor—your fingertips could be telling you more than you think.