That pit you see when someone presses a swollen leg may be a clue to something happening deep inside the body. Three organs deserve attention. 1. THE HEART: Think of it as a pump. When it weakens, blood backs up and pressure forces fluid into the legs. Doctors investigate with an ECG, BNP/NT-proBNP and an echocardiogram. Treatment may include diuretics and medicines that improve heart function. 2. THE KIDNEYS: These are the body's filters. When damaged, they may retain salt and water or leak protein into urine, allowing fluid to accumulate. Check kidney function, electrolytes and urine protein. Treatment depends on the cause and may include salt restriction, medication or dialysis. 3. THE LIVER: A damaged liver may produce less albumin, a protein that keeps fluid inside blood vessels. Blood tests, albumin levels and ultrasound help investigate. Treatment targets the liver disease and may include prescribed diuretics. ONE LEG SWELLING SUDDENLY??? That's an emergency waiting to happen! Never ignore it. A deep-vein blood clot can travel to the lungs, causing sudden breathlessness or death. Seek urgent medical care. The lesson for everyone: Treat the cause, not just the swelling.