Swelling results from accumulation of fluid in the tissues (edema). The swelling may cause weight gain. Swelling is usually most noticeable in the ankles and feet, but it may also involve the abdomen, lower back, hands, and face. If swelling is particularly severe, fluid may accumulate in the lungs, causing difficulty breathing.
Swelling may occur if the kidneys are unable to excrete excess water and sodium from the body, as in kidney failure. Swelling may also develop from a kidney disorder that causes the loss of large amounts of blood protein (especially albumin) in the urine (nephrotic syndrome). When the albumin level in the blood drops sufficiently, swelling occurs as fluid leaks from the circulation into the tissues.
Other disorders may also cause swelling. Heart failure, caused by inadequate pumping by the heart, signals the kidneys to retain salt and fluid, which may accumulate in tissues. Advanced liver disease also signals the kidneys to retain salt and fluid; swelling is worsened by the reduction in blood protein that occurs. This protein decrease causes fluid to leak into the tissues. If swelling occurs in only one limb, the cause is probably something related to the limb (such as a blood clot in a vein or an injury) rather than a kidney, heart, or liver problem.
Evaluation and Treatment
Doctors usually assess the presence and degree of swelling by pressing on the person's shins. If the skin retains the impression of the doctor's finger, extra fluid is present. The person's symptoms and the doctor's physical examination suggest whether the kidneys, liver, or heart is the cause, but doctors also obtain a urinalysis and blood tests of liver and kidney function. If heart failure is suspected, a chest x-ray and sometimes echocardiography are done. To diagnose nephrotic syndrome, doctors may assess urinary loss of protein by calculating the ratio of total protein to creatinine in a urine specimen.
The underlying disorder is treated when possible. Swelling can often be relieved by a diuretic if the kidneys are working properly. If the kidneys are not working properly and fluid has collected in the lungs, the person may need dialysis.
Last full review/revision March 2007 by Ralph E. Cutler, MD