Proteinuria and Nephrotic Syndrome
Conditions We Treat
Proteinuria & Nephrotic Syndrome
Protein in the urine is a warning sign that the kidney's filters are damaged. Identifying the cause — and treating it — requires a nephrologist.
What is proteinuria and nephrotic syndrome?
Proteinuria is the presence of abnormal amounts of protein in the urine. Healthy kidneys retain protein in the bloodstream; when the glomeruli (the kidney's filtering units) are damaged, protein leaks through into the urine. Mild proteinuria may be asymptomatic. Severe proteinuria — more than 3.5 grams per day — defines nephrotic syndrome.
Nephrotic syndrome is characterized by heavy proteinuria, low blood albumin (hypoalbuminemia), edema (swelling, particularly in the legs and around the eyes), and elevated cholesterol. It can be caused by primary kidney diseases — minimal change disease, focal segmental glomerulosclerosis (FSGS), membranous nephropathy, IgA nephropathy — or by systemic conditions such as diabetes, lupus, or amyloidosis.
Accurate diagnosis requires a kidney biopsy in most cases. Treatment depends entirely on the underlying cause — which is why a nephrologist, not a primary care physician, must lead the evaluation.
Common Causes
How we approach proteinuria and nephrotic syndrome
Quantify and characterize the proteinuria
We measure urine albumin-to-creatinine ratio and total protein-to-creatinine ratio to quantify the degree of protein leak and distinguish glomerular from tubular proteinuria.
Kidney biopsy when indicated
Most patients with nephrotic-range proteinuria require a kidney biopsy to identify the specific cause. The biopsy result determines treatment — there is no one-size-fits-all approach.
Immunosuppressive therapy
Many glomerular diseases respond to corticosteroids, calcineurin inhibitors, rituximab, or other immunosuppressive agents. We select and monitor these therapies carefully.
Supportive management
Edema, hyperlipidemia, thrombotic risk, and infection risk are all complications of nephrotic syndrome that require active management alongside disease-specific treatment.
Frequently asked questions
What does protein in the urine mean?
Protein in the urine (proteinuria) indicates that the kidney's filters are damaged and leaking protein that should stay in the bloodstream. Small amounts may be transient and benign; persistent or heavy proteinuria requires evaluation by a nephrologist.
What is nephrotic syndrome?
Nephrotic syndrome is defined by heavy proteinuria (more than 3.5 grams per day), low blood albumin, edema (swelling), and elevated cholesterol. It is caused by damage to the glomeruli and requires a kidney biopsy to identify the specific cause.
Do I need a kidney biopsy?
In most adults with nephrotic-range proteinuria or unexplained significant proteinuria, a kidney biopsy is necessary to identify the cause and guide treatment. The biopsy is performed by a nephrologist under ultrasound guidance and is generally safe.
Can nephrotic syndrome be cured?
It depends on the cause. Minimal change disease responds to steroids in most cases and can go into complete remission. FSGS and membranous nephropathy are more variable. Some causes are treatable; others require long-term management.
Related conditions
Protein in the urine requires a nephrologist.
We evaluate and treat all causes of proteinuria and nephrotic syndrome. Accepting new patients in Newport Beach.