Nephritic syndrome is a group of symptoms and signs that occur due to inflammation of the glomeruli, which are the filtering units of the kidneys. It is characterized by hematuria (blood in the urine), proteinuria (excess protein in the urine), edema (swelling), hypertension (high blood pressure), and decreased urine output.
The impaired function of the glomeruli results in the leakage of blood and protein into the urine. The blood in the urine gives it a red or cola-colored appearance, while the excessive protein loss can lead to a decrease in protein levels in the blood, causing fluid to accumulate in the tissues and cause edema.
Etiology;
The etiology or underlying causes, of nephritic syndrome can vary. Here are some common causes and associated conditions:
- Poststreptococcal glomerulonephritis: This is one of the most common causes of nephritic syndrome, especially in children. It occurs as a result of an immune response to a prior streptococcal infection, such as strep throat or skin infections.
- IgA nephropathy (Berger’s disease): It is a condition characterized by the buildup of immunoglobulin A (IgA) in the glomeruli. The exact cause is unknown, but it is thought to involve abnormal immune responses triggered by infections or other factors.
- Lupus nephritis: Systemic lupus erythematosus (SLE), an autoimmune disease, can affect the kidneys and cause nephritis syndrome. In lupus nephritis, the immune system mistakenly attacks the kidneys, leading to inflammation and damage.
- Membranoproliferative glomerulonephritis (MPGN): MPGN is a rare condition characterized by thickening and inflammation of the glomeruli. It can have both primary (idiopathic) and secondary causes, including infections (such as hepatitis C), autoimmune diseases, and certain medications.
- Goodpasture syndrome: This is a rare autoimmune disorder characterized by the presence of antibodies that attack the basement membrane in the glomeruli and lungs, leading to glomerulonephritis and pulmonary hemorrhage.
- Henoch-Schönlein purpura (HSP): HSP is a type of vasculitis that primarily affects small blood vessels, including those in the kidneys. It is characterized by a rash, joint pain, abdominal pain, and kidney involvement.
- Alport syndrome: It is a genetic disorder that affects the glomeruli and results in progressive kidney damage. It can cause nephritic syndrome, along with hearing loss and eye abnormalities.
Clinical manifestation:
The clinical manifestations of nephritic syndrome typically include:
Hematuria: Hematuria, the presence of blood in the urine, is a hallmark feature of nephritis syndrome. The urine may appear pink, red, or cola-colored. Hematuria can be microscopic (only detectable under a microscope) or macroscopic (visible to the naked eye).
Proteinuria: Proteinuria, the presence of excessive amounts of protein in the urine, is another common feature. Unlike in nephrotic syndrome, the degree of proteinuria is typically less severe in nephritic syndrome.
Edema: Edema, swelling caused by fluid retention, is commonly observed in nephritis syndrome. It usually occurs in the face, hands, feet, and ankles, but can also affect other parts of the body. Edema in nephritic syndrome is primarily due to sodium and water retention.
Hypertension: High blood pressure (hypertension) is a frequent finding in nephritic syndrome. It can result from several factors, including the activation of the renin-angiotensin-aldosterone system and the retention of sodium and water.
Decreased urine output: Nephritic syndrome can lead to a decrease in urine output or oliguria. The kidneys may have impaired filtration function, resulting in reduced urine production.
Fatigue and malaise: Patients with nephritic syndrome may experience fatigue, weakness, and a general feeling of malaise. These symptoms can be related to anemia, fluid retention, and the underlying inflammatory processes.
Hypoalbuminemia: Nephritic syndrome can cause a decrease in the level of albumin, a major protein in the blood. Low levels of albumin can contribute to the development of edema.
Renal impairment: Nephritic syndrome is characterized by inflammation and damage to the glomeruli, which can lead to impaired kidney function. This can manifest as reduced glomerular filtration rate (GFR) and increased levels of waste products (such as creatinine) and electrolyte imbalances.
Complications:
Nephritic syndrome can lead to several complications, including:
- Acute kidney injury (AKI): In severe cases, nephritic syndrome can cause acute kidney injury, which is a sudden loss of kidney function. This can occur due to the inflammation and damage to the glomeruli, resulting in decreased filtration and impaired kidney function.
- Chronic kidney disease (CKD): If nephritic syndrome is not effectively treated or controlled, it can progress to chronic kidney disease. Prolonged inflammation and glomerular damage can lead to irreversible kidney damage and decreased kidney function over time.
- Hypertension: Nephritic syndrome can contribute to the development of high blood pressure (hypertension). The underlying inflammation, sodium and water retention, and impaired kidney function can all contribute to increased blood pressure.
- Nephrotic-range proteinuria: In some cases, nephritic syndrome can progress to nephrotic-range proteinuria, where the amount of protein excreted in the urine becomes similar to that seen in nephrotic syndrome. This can lead to more severe hypoalbuminemia and edema.
- Renal vein thrombosis: The inflammation and damage to the glomeruli can increase the risk of blood clot formation in the renal veins, leading to renal vein thrombosis. This condition can further impair kidney function and cause pain and swelling in the affected area.
- Cardiovascular complications: Nephritic syndrome, particularly when associated with hypertension and dyslipidemia, can increase the risk of cardiovascular complications. These include heart disease, heart failure, and an increased risk of heart attacks and strokes.
- Infections: As with nephrotic syndrome, nephritic syndrome can also increase the susceptibility to infections due to the loss of immunoglobulins and other immune factors in the urine. Infections can be both localized, such as urinary tract infections, and systemic, such as sepsis.
- Complications in pregnancy: Nephritic syndrome can have implications for pregnancy. It can increase the risk of complications such as preeclampsia, preterm birth, and low birth weight babies.
Investigations:
The investigation of nephritic syndrome involves various tests and procedures to determine the underlying cause and assess kidney function. Here are some common investigations that may be performed:
Urine tests:
- Urinalysis: This test examines the urine for the presence of blood, protein, and other abnormalities.
- Urine protein-to-creatinine ratio: It measures the amount of protein in the urine relative to the level of creatinine, a waste product.
- Urine culture: This test helps identify any bacterial infection in the urinary tract.
Blood tests:
- Kidney function tests: These include measurements of blood urea nitrogen (BUN) and creatinine levels to assess kidney function.
- Serum electrolytes: Imbalances in electrolyte levels, such as sodium, potassium, and calcium, may be present in nephritic syndrome.
- Complete blood count (CBC): It can reveal changes associated with inflammation, anemia, or infections.
- Serum complement levels: Complement proteins, such as C3 and C4, may be measured to evaluate immune system activation and complement consumption.
Kidney imaging:
- Renal ultrasound: This non-invasive test uses sound waves to produce images of the kidneys, helping to identify structural abnormalities or obstruction.
- CT scan or MRI: These imaging techniques may be performed to obtain more detailed information about the kidneys and surrounding structures.
- Kidney biopsy: A kidney biopsy involves the removal of a small tissue sample from the kidney using a needle. The sample is examined under a microscope to determine the specific cause of nephritic syndrome and assess the extent of glomerular damage.
Serologic tests: Depending on the suspected cause, serologic tests may be ordered to detect specific antibodies or markers associated with certain conditions. Examples include antinuclear antibodies (ANA) for lupus nephritis or anti-streptolysin O (ASO) titers for post-streptococcal glomerulonephritis.
Treatment:
The treatment of nephritic syndrome aims to control the underlying cause, manage symptoms, and prevent complications. The specific treatment approach will depend on the underlying cause and the severity of the condition. Here are some common treatment strategies:
Medications:
- Corticosteroids: These anti-inflammatory medications, such as prednisone, are commonly used to reduce inflammation and suppress the immune response in nephritic syndrome. They may be prescribed for a specific duration and dose, depending on the underlying cause.
- Immunosuppressive drugs: In certain cases, such as lupus nephritis or severe glomerulonephritis, additional immunosuppressive medications may be prescribed, such as cyclophosphamide, mycophenolate mofetil, or rituximab. These drugs help to suppress the immune system and reduce inflammation.
- Blood pressure medications: Medications to control blood pressure, such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), may be prescribed to manage hypertension and reduce proteinuria.
- Diuretics: These medications, such as loop diuretics (e.g., furosemide), can help reduce fluid retention and edema.
- Anticoagulants: In certain cases, anticoagulant medications may be prescribed to prevent blood clots in individuals at high risk, such as those with renal vein thrombosis.
Dietary and lifestyle modifications:
- Sodium restriction: Limiting sodium intake can help manage fluid retention and hypertension.
- Protein restriction: In some cases, a moderate protein restriction may be recommended to reduce proteinuria.
- Fluid management: Monitoring and adjusting fluid intake may be necessary to balance hydration and prevent fluid overload.
Supportive measures:
Infections management: Prompt treatment of infections, such as antibiotics for bacterial infections, is important to prevent complications and minimize immune system activation.
Symptom management: Managing symptoms such as edema, hypertension, and fatigue through lifestyle modifications and medications can improve overall well-being.
Monitoring and follow-up:
Regular follow-up visits with a healthcare provider are essential to monitor kidney function, blood pressure, and response to treatment. This helps to detect any changes or complications and make adjustments to the treatment plan as needed.
It’s important to note that the treatment plan for nephritic syndrome should be individualized based on the underlying cause and the specific needs of the patient. Close collaboration with a healthcare provider, such as a nephrologist, is crucial to ensure optimal management and prevent long-term complications.