Diagnosis of Nephrotic Syndrome
In addition to a physical examination and the assessment of family health history, the following three tests are used to make a nephrotic syndrome diagnosis:
- Blood analysis
- Kidney biopsy
Blood analysis often shows high cholesterol levels and low albumin. BUN and creatinine may or may not be elevated. If bun and creatinine are elevated the patient has renal failure and the prognosis is worse.
Evaluation of the urine by a simple urine dipstick in the office can give preliminary information on the amount of protein in the urine. However, this test is a qualitative test. In order to determine the actual amount of protein in the urine, a 24-hour quantitative test must be done, which indicates levels of protein and creatinine in the urine. Often, a comparison of protein to creatinine based on a single sample is used to determine 24-hour protein loss. This is helpful for quicker results or when the patient cannot collect urine over 24 hours.
A closed kidney biopsy may be used to determine the underlying cause and extent of disease with the exception of the following cases.
- Children with NS most often have minimal change disease and respond well to a short course of steroids. A biopsy should only be considered if they do not show a favorable response to the steroids within 6-8 weeks.
- Adult patients with a history of diabetes who have tested negative to other disorders such as myeloma, infections, and collagen vascular diseases. It is presumed the cause of the proteinuria is diabetic nephropathy and a kidney biopsy is not necessary. If the duration of diabetes has been short or the severity of the NS is profound, a kidney biopsy is considered.
- Elderly patients, patients who are not expected to live long, or those for whom immunosuppressive drug therapy is not advisable are typically not candidates for a biopsy.
Nephrotic Syndrome Treatment
Nonspecific Treatment for Nephrotic Syndrome
Controlling hypertension is essential in reducing proteinuria. This is accomplished with angiotensin converting enzyme (ACE-1) inhibitors. ACE-1 inhibitors are the preferred blood pressure lowering medication because they provided added protection to the kidneys. These drugs interfere with the production of angiotensin II (AII), a chemical (vasoactive) produced in the body. AII causes vascular constriction, which increases blood pressure, including pressure in the glomeruli. This causes scarring of the kidney and exacerbates proteinuria, which accelerates the loss of renal function. ACE-1 inhibitors encourage circulation, lower blood pressure in the body, and decrease pressure in the glomeruli. This decreases protein spillage and helps to delay progressive scarring of the glomeruli.
Patients with hypertension benefit from ACE-1 inhibitors, as aggressive blood pressure control is key to protecting the kidneys and the cardiovascular system. The goal is to lower the systolic blood pressure below 130 and the diastolic below 80.
ACE-1 inhibitors cause a dry cough in approximately 8 percent of patients who take them.
ACE-1 inhibitors are given in the highest dose tolerable to ensure kidney protection. If a patient develops a cough, a new class of drugs may be used, known as angiotensin receptor blockers (ARB). ARBs work by blocking angiotensin receptors, which blocks the effects of angiotensin after it is produced. They offer the same kidney protection as ACE-1 inhibitors without causing cough. If tolerable, ARBs may be combined with an ACE-1 inhibitor for added benefit.
Treating high cholesterol (hypercholesterolemia) typically involves medication and proper diet.
It is generally considered healthy to eat one gram of protein daily for every kilogram of body weight; physicians usually help their patients define a diet that is appropriate for kidney health.
Specific Treatment for Nephrotic Syndrome
Specific treatment is given for the following underlying causes of nephrotic syndrome:
- Glomerular disease
- Minimal change disease
- Renal failure
Treating minimal change disease in children usually involves the use of diuretics to reduce edema and a corticosteroid called prednisone (Liquid Pred), which usually resolves proteinuria in a couple of weeks. Corticosteroids heal the ongoing damage at the level of the glomerular basement membrane (i.e., they patch the holes that are allowing the proteins to leak through).
About 30 percent of children treated with prednisone have no recurrence of disease, roughly 20 percent relapse after several months, and the remaining 50 percent relapse a short time after discontinuing the medication.
Nephrotic Syndrome Prognosis
The outcome of NS varies and is largely dependent on the underlying cause. Some patients may have a spontaneous recovery not requiring any specific therapy, while others worsen despite aggressive, specific therapy.
Complications that can arise during treatment include atherosclerosis "hardening of the arteries" and adverse reaction to medications such as steroids. Some severe side effects that can occur with the use of steroids include osteoporosis, cataract development, increased risk of infection, and diabetes.