Membranous nephritis is an autoimmune disorder of the kidney. An autoimmune disorder is a condition in which your immune system mistakes your body’s own cells for a foreign invader, and creates immune complexes against them. In membranous nephritis, immune complexes are deposited within the walls of capillaries inside the kidney. This causes the capillary walls to thicken, which diminishes their ability to filter blood. As the kidney becomes unable to filter the blood, proteins escape from the capillaries, resulting in high blood pressure, fluid retention, high cholesterol and proteins in the urine. Treatment includes correcting the underlying condition as well as making several dietary changes.
Decrease Salt Intake
A diet low in salt content should be followed if swelling of the hands or feet is present. The American Heart Association recommends consuming no more than 1500mg of sodium a day. You can reduce the amount of sodium in your diet by avoiding processed foods, which tend to be high in sodium, and choosing fresh foods instead. In particular, canned foods, broths, soups, pretzels, chips and condiments typically contain the most sodium. Look for foods labeled “low sodium,” meaning it contains less than 140mg of sodium. Also avoid adding salt to foods. Just ¼ teaspoon of salt adds 600mg of sodium, which is almost half your daily allowance for salt.
Limit Consumption of Protein
Protein consumption should be limited in those with proteinuria, a condition in which protein is present in the urine. Proteinuria is dangerous because it can damage the kidney and even lead to kidney failure. It also contributes to swelling of the body due to loss of proteins. MedlinePlus recommends a moderate protein intake of about one gram of protein per kilogram of body weight a day.
Vitamin D Supplementation
Vitamin D supplementation may be required for patients with chronic membranous nephritis that is not responsive to treatment. Vitamin D is converted to its active form, 1,25-dihydroxyvitamin D, in the kidney. In chronic kidney disease, the ability of the kidney to synthesize this vitamin is reduced, therefore supplementation is sometimes warranted. The recommended dietary allowance of vitamin D is 15mcg a day for adults ages 19 to 70 years and 20mcg a day for adults age 71 years and older.
Reduce Fat and Cholesterol
A low fat, low cholesterol diet should be followed to avoid further elevation of cholesterol levels associated with membranous nephritis and to lower the risk of cardiovascular events. Dietary modification alone, however, will not lower your cholesterol as it is primarily caused by an increase in cholesterol synthesis by the liver and not because of diet. Saturated fats should be avoided as well as foods high in cholesterol. This includes foods such as eggs, whole milk, butter, fatty cuts of meats and fried foods. Your doctor may recommend a cholesterol lowering medication such as a statin to keep your cholesterol levels under control.