Nutrition therapy for nephrotic syndrome

You have probably worked with many patients with chronic kidney disease (CKD), but nephrotic syndrome is not as common. Nephrotic syndrome is another condition of impaired renal function, although it is not recognized as a specific disease state. Understanding the specifics of this syndrome and how it might impact nutritional recommendations is beneficial for the RDN and can improve overall care with these patients.

Terminology review

Several different medical terms are likely to be seen with the diagnosis of nephrotic syndrome. Some you may recognize, while others may not be as familiar. Reviewing these terms can be helpful in navigating this diagnosis and the best approach for tackling nutrition care with these individuals.

Proteinuria. This term refers to protein in the urine. Many causes are associated with some form of kidney impairment. With nephrotic syndrome, urinary protein loss is greater than 3 grams per day.

Albuminuria. This symptom occurs when the barrier used for filtration of the kidneys is damaged, resulting in albumin being passed into the urine. Newer terms have replaced the previous language of microalbuminuria and macroalbuminuria. Instead, urine albumin measuring between 30 to 300 grams per day is considered moderately increased albuminuria. Greater than 300 grams per day of urine albumin is referred to as severely increased albuminuria.

Hypoalbuminemia. A term reflecting decreased amounts of albumin within the blood. In nephrotic syndrome, it is associated with increased loss of albumin into the urine. In adults, a normal range of albumin in the blood is 3.5 to 5.5 g/dL.

Edema. Designated as swelling in the body’s tissues due to fluid shifts or changes with kidney filtration, edema is often seen with nephrotic syndrome.

Hyperlipidemia. Terminology reflecting an abnormal increase of lipids in the blood. With nephrotic syndrome, high cholesterol (> 240 mg/dL) and high triglycerides (> 150 mg/dL) may be of concern.

What is nephrotic syndrome?

The nephrotic syndrome is a collection of symptoms that often stems from diabetes, glomerular disorders, minimal change disease, or focal segmental glomerulosclerosis. This condition occurs when the glomeruli in the kidney’s nephrons are inflamed and more permeable, allowing abnormal passage of protein and other larger molecules into the urine. Diagnosis usually requires a urine analysis to determine the type and amount of protein present. A kidney biopsy may also be ordered to determine the initial cause of the nephrotic syndrome.

The clinical presentation of the nephrotic syndrome may vary slightly from CKD. Symptoms of this disorder are proteinuria, hypoalbuminemia, high blood pressure, hyperlipidemia, and fluid retention or edema. A combination of medications and diet can support treatment in these patients.

Nutrition therapy 

Avoid a high protein diet. Too much protein can worsen urinary protein loss. Individual protein needs should be similar to those recommended for each CKD stage. For individuals with early phases of CKD, an average of 0.8 g/kg body weight is recommended.

Monitor total sodium intake. Limiting total salt intake is also recommended in the patient with nephrotic syndrome. Goals should include no more than 2,300 milligrams per day to prevent edema and to maintain a healthy blood pressure.

Balance electrolytes to maintain levels within normal limits. Changes with electrolytes such as potassium may occur as part of the nephrotic syndrome. Adjusting dietary intake to help maintain electrolytes within normal range may be needed.

Consider a “heart healthy” diet. With an increased risk for hyperlipidemia due to the nephrotic syndrome, total dietary fat should be evaluated. Limiting total fat intake and avoiding foods high in saturated fat and trans fat is encouraged.

Maintain goal vitamin D levels. Tracking vitamin D level in the patient with impaired kidney function is important because of the many roles this vitamin plays in the body. If insufficient, supplementation should be provided with cholecalciferol or ergocalciferol. 

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References:

Cleveland Clinic. Albumin Blood Test. Available at https://my.clevelandclinic.org/health/diagnostics/22390-albumin-blood-test. Accessed November 20, 2022.

Cleveland Clinic. Hyperlipidemia. Available at https://my.clevelandclinic.org/health/diseases/21656-hyperlipidemia. Accessed November 20, 2022.

Gonyea J, Phillips S. Pathophysiology of the Kidney. Clinical Guide to Nutrition Care in Chronic Kidney Disease. 3^rdedition. Chicago, IL: Academy of Nutrition and Dietetics;2022:5-6.

National Institute of Diabetes and Digestive and Kidney Diseases. Nephrotic Syndrome in Adults. Available at https://www.niddk.nih.gov/health-information/kidney-disease/nephrotic-syndrome-adults. Accessed November 18, 2022.