Patient information: Glomerular disease overview

GLOMERULAR DISEASE OVERVIEW

Glomerular disease reduces the ability of the kidneys to maintain a balance of certain substances in bloodstream. Normally, the kidneys should filter toxins out of the bloodstream and excrete them in the urine, but should keep red blood cells and protein in the bloodstream. In people with glomerular disease, red blood cells and protein may be excreted into the urine, while toxins may be retained.

Glomerular disease can occur by itself (eg, affecting only the kidney), or may be associated with an underlying medical condition that affects other organ systems, such as lupus, diabetes, or certain infections. Glomerular disease can develop suddenly (called acute), or develop slowly over a period of years (called chronic). Treatment of glomerular disease depends upon its cause and type.

NORMAL KIDNEY FUNCTION

To understand glomerular disease, it may be helpful to understand how the kidneys normally function. The kidneys are bean-shaped, approximately fist-sized organs that are located in the mid-back, just below the rib cage on each side of the body (figure 1 and figure 2).

They kidneys filter the body's blood supply with tiny structures, known as the nephron (figure 3). Each nephron is composed of a glomerulus and a tubule. The glomerulus filters wastes and excess fluids, while the tubules modify the waste to form urine. Glomerular disease affects the glomerulus, causing it to filter and excrete incorrectly.

GLOMERULAR DISEASE FEATURES

Signs and symptoms of glomerular disease depend upon the cause. The first sign of a problem may be an abnormal urine test (urinalysis) that was performed for other reasons.

• The urinalysis may show red blood cells, which normally should not be present.
• The urine may be discolored; red blood cells in the urine can cause the urine to become a light or dark brown color (called hematuria). (See "Patient information: Blood in the urine (hematuria) in adults".)

• Excessive protein in the urine (called proteinuria) can cause the urine to appear foamy in the toilet. (See "Patient information: Protein in the urine (proteinuria)".)

Signs and symptoms may also include an elevated blood pressure (greater than 140/90 mmHg), fluid retention (edema) in the hands, face, feet, and/or abdomen, fatigue (due to anemia or kidney failure), or urinating infrequently. (See "Patient information: Edema (swelling)".)

TYPES OF GLOMERULAR DISEASE

The three basic types of glomerular disease include: focal nephritic, diffuse nephritic, and nephrotic. (See "Differential diagnosis of glomerular disease".)

Focal nephritic — The key feature of focal nephritic disease is blood in the urine (hematuria) without significant impairment of kidney function or proteinuria. A person with focal glomerulonephritis may not have any symptoms and their condition may go unnoticed until blood and protein are found during a routine urinalysis.

The following conditions may cause focal glomerulonephritis.

• Less than 15 years old — Mild postinfectious glomerulonephritis, IgA nephropathy, thin basement membrane disease, hereditary nephritis, Henoch-Schönlein purpura, mesangial proliferative glomerulonephritis
• 15 to 40 years old — IgA nephropathy, thin basement membrane disease, lupus, hereditary nephritis, mesangial proliferative glomerulonephritis
• Greater than 40 years old — IgA nephropathy

Diffuse nephritic — Persons with diffuse nephritic disease have hematuria with impaired kidney function and proteinuria. This may be a severe form of focal nephritic disease for some people, or may be caused by a bodywide disease. Urinalysis may also show high levels of protein, and patients may have edema (swelling in the lower legs) or high blood pressure.

The following conditions may cause diffuse glomerulonephritis.

• Less than 15 years old — Postinfectious glomerulonephritis, membranoproliferative glomerulonephritis
• 15 to 40 years old — Postinfectious glomerulonephritis, lupus, rapidly progressive glomerulonephritis, fibrillary glomerulonephritis, membranoproliferative glomerulonephritis
• Greater than 40 years old — Rapidly progressive glomerulonephritis, vasculitis (including mixed cryoglobulinemia), fibrillary glomerulonephritis, postinfectious glomerulonephritis

Nephrotic syndrome — People with nephrotic syndrome generally have protein in the urine (proteinuria) but little to no blood in the urine (hematuria). Kidney function may worsen as nephrotic syndrome progresses. (See "Patient information: The nephrotic syndrome".)

The following conditions may cause nephrotic syndrome.

• Less than 15 years old — Minimal change disease, focal glomerulosclerosis, mesangial proliferative glomerulonephritis
• 15 to 40 years old — Focal glomerulosclerosis, minimal change disease, membranous nephropathy (including lupus), diabetic nephropathy, preeclampsia, postinfectious glomerulonephritis (later stage)
• Greater than 40 years old — Focal glomerulosclerosis, membranous nephropathy, diabetic nephropathy, minimal change disease, IgA nephropathy, primary amyloidosis or the related disorder light chain deposition disease (which can account for 15 to 20 percent of cases in patients over the age of 60), benign nephrosclerosis (often due to high blood pressure), postinfectious glomerulonephritis (later stage)

GLOMERULAR DISEASE DIAGNOSIS

Glomerular disease is diagnosed based upon blood or urine tests. Other tests, including imaging tests and/or a kidney biopsy, may be used to help diagnose the specific type of glomerular disease.

Urine tests — The urinalysis may show red blood cells (which are seen when there is damage or inflammation in the glomeruli), white blood cells (which can indicate inflammation), or increased protein levels (which is an indicator of glomerular damage).

Blood tests — Blood tests are used to measure the level of creatinine and blood urea nitrogen (BUN), which become elevated when the kidneys are damaged and are not filtering properly. Blood tests may also be used to diagnose underlying medical conditions (such as diabetes, lupus, or certain infections).

Imaging tests — An ultrasound of the kidney is frequently recommended if glomerular disease is suspected, primarily to rule out other causes of blood in the urine and/or decreased kidney function. The ultrasound can also measure the size of the kidneys, which can provide a clue as to the duration of the kidney disease.

Kidney biopsy — A kidney (renal) biopsy may be needed to definitively determine the cause of glomerular disease in patients that cannot be diagnosed by blood tests or imaging tests alone. A separate topic review discusses renal biopsy. (See "Patient information: Renal (kidney) biopsy".)

GLOMERULAR DISEASE TREATMENT

The treatment of glomerular disease depends upon the form (acute or chronic), the underlying cause, and the severity of associated signs and symptoms. Some forms of glomerular disease, such as that caused by infection, improve after the infection is treated.

Other types of glomerular disease may require treatment with immune suppressant medications, such as glucocorticoids (commonly called steroids). Rapidly progressive glomerulonephritis is sometimes treated with plasmapheresis, which removes components of the blood that could be causing the inflammation. Some forms of glomerular disease do not require treatment, while others do not respond to any therapy.

Manging high blood pressure — Management of high blood pressure is important to prevent further damage to the kidneys; one or more medications may be needed. One or more high blood pressure medications may be recommended for patients with chronic glomerular disease to decrease the amount of protein in the urine and slow the rate of progression of kidney disease. (See "Patient information: High blood pressure treatment in adults" and "Patient information: High blood pressure, diet, and weight".)

GLOMERULAR DISEASE COMPLICATIONS

Some types of glomerular disease are associated with complications, including high blood pressure, acute or chronic kidney failure, and nephrotic syndrome. (See "Patient information: The nephrotic syndrome".)

High blood pressure — High blood pressure can develop in people with glomerular disease due to kidney damage and build up of waste products and excess fluid in the bloodstream. One or more medications may be needed to reduce blood pressure and prevent further damage to the kidneys. (See "Patient information: High blood pressure treatment in adults".)

Acute kidney failure — Sudden onset (acute) kidney failure is more likely to occur with acute glomerulonephritis (eg, diffuse nephritic). If the glomeruli are unable to filter the blood adequately, waste products and excess fluids build up in the bloodstream quickly. Hemodialysis may be needed to remove waste products and excess fluids. This could be temporary, until the kidney function recovers, or may be long-term if the kidneys become damaged. (See "Patient information: Hemodialysis".)

Chronic kidney failure — If kidney function continues to worsen, dialysis or kidney transplantation may be needed to perform the normal functions of the kidneys. There are two types of dialysis: hemodialysis and peritoneal dialysis. (See "Patient information: Hemodialysis" and "Patient information: Peritoneal dialysis".)

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two people are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: Blood in the urine (hematuria) in adults
Patient information: Protein in the urine (proteinuria)
Patient information: Edema (swelling)
Patient information: The nephrotic syndrome
Patient information: Renal (kidney) biopsy
Patient information: High blood pressure treatment in adults
Patient information: High blood pressure, diet, and weight
Patient information: Hemodialysis
Patient information: Peritoneal dialysis

Professional Level Information:
Diagnostic approach to the patient with acute or chronic kidney disease
Differential diagnosis of glomerular disease
Evaluation of hematuria in adults
Evaluation of isolated proteinuria in adults
Hematuria: Glomerular versus extraglomerular bleeding
Mechanisms of immune injury of the glomerulus
Pathogenesis of tissue injury in glomerulonephritis

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/healthtopics.html)

• National Institute of Diabetes and Digestive and Kidney Diseases

      (www.niddk.nih.gov)

• National Kidney Foundation

      (www.kidney.org)

• American Kidney Fund

      (www.akfinc.org)

• American Association of Kidney Patients

      (www.aakp.org)