Published by PMR of NY & CT
When you or your child is diagnosed with nephrotic syndrome, swelling is often the first thing you want to fix, and food can help. A nephrotic syndrome diet usually means less salt, a normal rather than high amount of protein and heart-healthy fats, while medicines treat the underlying kidney problem.
You may also see the term nephritic syndrome. It is a different condition, in which inflamed kidney filters leak blood and smaller amounts of protein into the urine, often with high blood pressure and less urine.
Your plan should come from your nephrologist and, ideally, a renal dietitian, because needs vary with the cause, your labs and your medicines.
What happens in nephrotic syndrome
Your kidneys contain tiny filters called glomeruli. In nephrotic syndrome, damaged filters let large amounts of protein, mostly albumin, escape into the urine. That leads to a recognizable pattern:
- Swelling in the legs, ankles or belly, or around the eyes in the morning
- Foamy urine, a common sign of protein in urine
- Low albumin in the blood
- High cholesterol and triglycerides
- A higher risk of infections and blood clots
In children, the most common cause is minimal change disease. In adults, causes include diabetes, lupus, focal segmental glomerulosclerosis and membranous nephropathy. A nephrologist confirms the diagnosis with blood and urine tests and sometimes a kidney biopsy.
Sodium: the cornerstone of a nephrotic syndrome diet
Salt makes your body retain water, so it feeds the swelling. Water pills (diuretics), a common treatment, also tend to work better when sodium intake stays low. Your nephrologist will usually ask you to eat less sodium than the general limit for healthy adults and may give you a daily target.
A few habits make that target easier to reach:
- Weigh yourself each morning, after using the bathroom and before breakfast, and write it down. A quick gain often means fluid is building up.
- Keep simple low-salt meals ready for busy days, when takeout is most tempting.
- Show your dietitian a few days of food notes to find hidden sodium.
Protein: why more isn't better
Eating extra protein to replace what is lost seems logical, but research hasn't supported it. A high-protein diet doesn't raise blood albumin much, and it can increase the amount of protein that leaks into the urine and add strain on the kidneys.
Most adults following a nephrotic syndrome diet are advised to eat a normal, moderate amount of good-quality protein, such as fish, poultry, eggs, dairy, beans or tofu, spread through the day. Your renal dietitian can set the amount for your size and kidney function. Skip protein powders and shakes unless your care team recommends them.
Fats and cholesterol
Cholesterol and triglycerides often climb in nephrotic syndrome, partly because the liver makes more cholesterol as blood protein falls. Heart-friendly choices help: fish and skinless poultry more often than fatty red meat, plant oils for cooking, and fiber from oats, beans and produce.
Diet alone usually can't normalize cholesterol while protein is still leaking, so your nephrologist may also prescribe a statin. Levels often improve once the condition goes into remission.
Fluids, steroids and other medicine-related changes
Fluid needs and several common medicines affect what you eat:
- Fluids. Many people don’t need a fluid limit. If swelling is severe or blood sodium is low, your doctor may set one.
- Steroids such as prednisone. They often increase appetite and can raise blood sugar and weaken bones and muscles over time, so your doctor may check calcium and vitamin D. Physical therapy can help you rebuild strength if steroids have left your legs weak.
- Water pills. Some lower potassium and others raise it, so your blood tests decide whether you need more or less. Ask before using a salt substitute, since many are made with potassium.
- Blood thinners. If you take warfarin because of clot risk, keep your intake of vitamin K-rich leafy greens steady rather than avoiding them.
Warning signs to report right away
Call your nephrologist promptly if you notice:
- Rapid weight gain or swelling that spreads
- Foamy urine returning after a period of remission
- Much less urine than usual
- Fever, chills or other signs of infection, especially while taking steroids
Get same-day care for a swollen, painful or warm leg, which can signal a blood clot. Call 911 for chest pain, sudden shortness of breath, coughing up blood, fainting or confusion. In a child with nephrotic syndrome, belly pain with fever needs urgent medical care.
Frequently asked questions
Can diet alone treat nephrotic syndrome?
No. Food can ease swelling and protect your heart and kidneys, but it can't stop the protein leak. Depending on the cause, treatment may include steroids or other immune-suppressing medicines and blood pressure medicines that reduce protein loss, plus water pills and cholesterol medicine for complications. Your nephrologist will explain which treatments fit your situation and how diet supports them.
What should a child with nephrotic syndrome eat?
Usually the same healthy meals as the rest of the family, with less salt, especially during a relapse or while taking steroids. Steroids can make children very hungry, so keep fruit, vegetables, yogurt and other filling snacks within reach. Don't cut protein or fluids unless the pediatric nephrologist advises it, and ask about a pediatric dietitian if mealtimes feel stressful.
Does foamy urine mean I have kidney disease?
Not always. Urine can foam briefly from a forceful stream or when it is concentrated. Foam that shows up every time, or lingers, may mean protein is leaking and is worth a simple urine test from your doctor. Some people with nephrotic syndrome check their urine at home with test strips to catch a relapse early.
How PMR can help
Your nephrologist and renal dietitian lead care for nephrotic syndrome. If swelling, steroid-related weakness or joint pain makes it hard to stay active, Physical Medicine & Rehabilitation of NY & CT (PMR) can help you move more comfortably. Meet our team, or request an appointment and we will contact you to schedule your visit.
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