In this situation, the people have a problem with kidney function due to a filtration problem involving proteins. Proteins spills through the kidney and into the urine. The heavy loss of protein in the urine (over grams per day) with its accompanying edema is termed the nephrotic syndrome . Nephrotic syndrome results in a reduction in the concentration of albumin in the blood (hypoalbuminemia). Since albumin helps to maintain blood volume in the blood vessels, a reduction of fluid in the blood vessels occurs. The kidneys then register that there is depletion of blood volume and attempt to retain salt. Consequently, fluid moves into the interstitial spaces causing pitting edema.
Treatment may also involve positioning the affected body parts to improve drainage. For example, swelling in feet or ankles may be reduced by having the person lie down in bed or sit with the feet propped up on cushions. Intermittent pneumatic compression can be used to pressurize tissue in a limb, forcing fluids – both blood and lymph – to flow out of the pressurized area. Treatment of persistent edemas, such as idiopathic bilateral lymphedema , may also use manual lymphatic drainage , a low-pressure massage technique designed to pump lymphatic fluid by a similar mechanism.