What Is Nephrotic Syndrome?
Nephrotic syndrome isn't a disease on its own-it's a set of signs that tell you something’s wrong with your kidneys. The big three? Heavy proteinuria, severe swelling (edema), and low blood albumin. When your kidneys leak too much protein into your urine, your body can’t hold onto fluid anymore. That’s when swelling shows up-around your eyes in the morning, in your ankles by evening, or even in your belly and lungs in serious cases.
This happens because the tiny filters in your kidneys, called glomeruli, get damaged. Normally, they keep big proteins like albumin in your blood. But when the filters break down-often because of injured podocytes or faulty proteins like nephrin-protein escapes into your urine. In adults, that’s more than 3.5 grams a day. In kids, it’s over 40 mg per square meter of body surface per hour. The result? Your blood loses its ability to pull water back in, and fluid pools where it shouldn’t.
Why Do You Swell So Badly?
The swelling isn’t just annoying-it’s a direct result of your body’s chemistry going off track. Low albumin in your blood means your blood can’t hold onto water anymore. So fluid leaks into your tissues. You might notice your socks leave deep marks, your face looks puffy when you wake up, or your shoes feel tight without gaining weight from food.
But here’s what many don’t realize: the body tries to fix this by holding onto salt and water. That makes the swelling worse. And it’s not just your legs. In severe cases, fluid builds up in the abdomen (ascites) or around the lungs (pleural effusion), making it hard to breathe. Adults with albumin levels below 2.0 g/dL are at serious risk for this.
Parents of young children often mistake the puffiness around the eyes for allergies. In fact, nearly 80% of childhood cases are initially misdiagnosed because the symptoms look like a cold or sinus issue. The delay? On average, 7 to 10 days. That’s why knowing the signs matters.
Proteinuria: The Silent Red Flag
One of the first clues? Foamy urine. It’s not just bubbles from the toilet. If your urine looks like beer foam and stays that way for minutes, that’s protein rushing out. About 65% of adults with nephrotic syndrome report this as their first symptom.
Doctors don’t just guess-they measure it. A 24-hour urine collection is the gold standard. If you’re excreting more than 3.5 grams of protein in a day, that’s a clear signal. For kids, it’s measured differently, but the principle is the same: too much protein out, not enough in.
But proteinuria doesn’t just cause swelling. It’s tied to high cholesterol. Your liver tries to make up for lost protein by cranking out lipids. Cholesterol levels often shoot above 300 mg/dL. That’s not just a lab number-it raises your risk of heart disease and blood clots.
What Causes It?
Age matters a lot. In children under 6, 80-90% of cases are caused by minimal change disease-a condition where the kidney filters look normal under a microscope but still leak protein. It’s often triggered by infections or allergies, and it responds well to steroids.
But in adults, the story changes. Focal segmental glomerulosclerosis (FSGS) is the top cause, making up 40% of cases. Membranous nephropathy comes next at 30%. And if you’re over 65, diabetes is likely the culprit, responsible for 30-40% of cases. Other causes include lupus, hepatitis B or C, and even certain medications like NSAIDs or penicillamine.
Then there’s the rare but serious genetic form: congenital nephrotic syndrome. Babies with this show massive protein loss-over 10 grams a day-within the first three months of life. It’s caused by mutations in genes like NPHS1 and requires specialized care, not just steroids.
How Is It Diagnosed?
It starts with a urine test. A dipstick showing 3+ or 4+ protein means you need more tests. Blood tests check albumin (normal is 3.5-5.0 g/dL; in nephrotic syndrome, it’s often below 2.5 g/dL) and cholesterol. A 24-hour urine collection confirms the protein loss.
But here’s the key: not everyone needs a kidney biopsy. In kids with classic symptoms and no other health problems, doctors often start steroids right away. If the child responds within 4 weeks, it’s almost certainly minimal change disease.
Adults? Biopsy is usually needed. Why? Because the causes are more varied, and treatment depends on what’s actually damaging the kidney. If it’s FSGS, lupus, or diabetes, the approach changes completely.
Treatment: Steroids, Drugs, and Lifestyle
For children with minimal change disease, prednisone is the first-line treatment. Dosed at 60 mg per square meter of body surface (up to 80 mg total), it usually brings remission in 4 weeks. Remission means no protein in the urine for three days straight. But relapses are common-up to 70% of kids will have another episode, often after a cold or flu.
Adults respond less predictably. Only 60-70% get full remission with steroids. And side effects? Moon face, weight gain, mood swings, and increased appetite are common. One study found 68% of pediatric patients gained 10-20% of their body weight on steroids.
When steroids don’t work-or come with too many side effects-doctors turn to other drugs:
- Calcineurin inhibitors like tacrolimus or cyclosporine: Used for steroid-resistant cases. They suppress the immune system differently and can cut proteinuria by half.
- Rituximab: A biologic that targets B-cells. Used in frequent relapsers or steroid-dependent patients. It’s expensive-up to $2,500 a month-but can keep people off steroids for years.
- ACE inhibitors or ARBs: These aren’t just for blood pressure. They directly reduce protein leakage. All patients, even kids, should be on one if their blood pressure allows. They can lower proteinuria by 30-50%.
Diet and Daily Management
What you eat matters. Sodium is the enemy. Cutting salt to under 2,000 mg a day can reduce swelling by 30-50% in just three days. That means no processed food, no canned soups, no fast food. Read labels-salt hides everywhere.
Protein intake? Don’t go low. Eating too little protein (under 0.8 g per kg of body weight) can make your body break down muscle to compensate. But don’t overdo it either. Stick to 0.8-1.0 g per kg. Good sources: eggs, lean meat, tofu, low-fat dairy.
Cholesterol? Focus on healthy fats-avocados, nuts, olive oil. Avoid trans fats and fried foods. Statins may be added if diet isn’t enough.
And don’t forget vaccines. Live vaccines like MMR or chickenpox are dangerous during steroid treatment. Get them done before starting immunosuppressants. Flu and pneumonia shots? Safe and recommended.
The Hidden Danger: Blood Clots
One of the most overlooked risks? Blood clots. Nephrotic syndrome makes your blood thicker and stickier. Your body loses proteins that normally prevent clotting. The risk of deep vein thrombosis or pulmonary embolism goes up 2-4 times.
Renal vein thrombosis-a clot in the kidney’s main vein-is especially common in adults with albumin below 2.0 g/dL. It can cause sudden flank pain, blood in the urine, or a rapid drop in kidney function.
Doctors don’t always start blood thinners right away. But if you’re bedridden, have a history of clots, or your albumin is very low, anticoagulation is often recommended. Don’t ignore swelling in one leg, shortness of breath, or chest pain.
What’s New in Treatment?
The field is changing fast. In 2023, the FDA approved budesonide (Tarpeyo) for IgA nephropathy-and it’s showing promise in some FSGS cases too, reducing proteinuria by up to 59%.
The PROTECT study in 2022 tested sparsentan, a new drug that blocks two pathways involved in kidney damage. It cut proteinuria by 47.6% compared to just 14.7% with standard care. It’s not yet approved for nephrotic syndrome, but trials are ongoing.
Researchers are also looking at targeted therapies. The NEPTUNE study found three molecular subtypes of FSGS. One responds to steroids, another doesn’t. Future treatment may be based on your genetic profile, not just your symptoms.
And in the lab, Rho kinase inhibitors are showing 60-70% reduction in proteinuria in animal models. These could one day protect the kidney’s filtering cells directly.
Long-Term Outlook
Prognosis depends entirely on the cause. If you have minimal change disease, your chance of keeping your kidneys healthy for 10 years is 95%. FSGS? 50-70%. Membranous nephropathy? 60-80%. But if diabetes caused it, your survival drops to 40-50%.
The biggest red flag? If proteinuria stays above 1 gram per day after treatment. That increases your risk of kidney failure by 4.2 times. That’s why getting to complete remission-not just partial-is critical.
Relapses are part of the journey, especially in kids. But with good management-meds, diet, monitoring-most people live full lives. The goal isn’t just to reduce swelling. It’s to protect your kidneys for decades.
What to Do Next
If you or your child has foamy urine, unexplained swelling, or sudden weight gain, see a doctor. Don’t wait. Early diagnosis means better outcomes.
Keep a symptom diary: note swelling, urine appearance, weight changes, and any infections. Bring it to your nephrologist. Ask about a 24-hour urine test and albumin levels. If you’re on steroids, ask about bone health, eye checks, and vaccination timing.
And remember: this isn’t a life sentence. With the right care, many people go into long-term remission. The key is sticking with treatment, watching for relapses, and staying informed about new options.
