Nephritic Syndrome (Hematuria)

What is Nephritic Syndrome (Hematuria)?

Nephritic syndrome is a collection of clinical findings that result from inflammation of the glomeruli, the tiny filtering units of the kidneys. The hallmark sign is hematuria—the presence of red blood cells in the urine—often visible as a pink, red, or brown discoloration. In addition to hematuria, patients typically have proteinuria (usually < 3 g/day), hypertension, decreased urine output, and varying degrees of kidney impairment.¹ The term “nephritic” distinguishes this inflammatory picture from “nephrotic” syndrome, which is dominated by heavy protein loss.

Common Causes

Numerous diseases can trigger an inflammatory response in the glomeruli, leading to nephritic syndrome. The most frequently encountered causes include:

• IgA nephropathy (Berger disease) – the most common primary glomerulonephritis worldwide.
• Post‑streptococcal glomerulonephritis (PSGN) – follows infection with nephritogenic strains of Streptococcus pyogenes.
• Lupus nephritis – renal involvement in systemic lupus erythematosus (SLE).
• Rapidly progressive glomerulonephritis (RPGN) – a group of severe, crescentic diseases (e.g., anti‑GBM disease, ANCA‑associated vasculitis).
• Membranoproliferative glomerulonephritis (MPGN) – associated with complement dysregulation or hepatitis C.
• Alport syndrome – a hereditary disorder of type IV collagen causing progressive hematuria.
• Infection‑related glomerulonephritis – e.g., hepatitis B, hepatitis C, HIV, or endocarditis.
• Drug‑induced GN – caused by medications such as penicillamine, gold salts, or NSAIDs.
• Henoch‑Schönlein purpura (IgA vasculitis) – a small‑vessel vasculitis that often presents with skin rash and renal involvement.
• Metabolic diseases – e.g., diabetes‑related GN with a nephritic component, though less common.

Associated Symptoms

While hematuria is the defining feature, patients often experience a constellation of other signs:

• Dark, tea‑colored or cola‑colored urine (gross hematuria).
• Foamy or mildly protein‑laden urine.
• Puffy or “bloated” face and periorbital edema, especially in the morning.
• High blood pressure (often newly diagnosed).
• Reduced urine output (oliguria) or a feeling of incomplete emptying.
• Flank or abdominal pain in some glomerulonephritides.
• Systemic signs such as fever, rash, joint pain, or sore throat when the underlying cause is infectious or immune‑mediated.

When to See a Doctor

Early evaluation can prevent permanent kidney damage. Seek medical attention if you notice:

• Visible blood in the urine that persists for more than 24 hours.
• New or worsening high blood pressure.
• Significant swelling of the face, hands, or feet.
• Decreased urine volume or an inability to urinate.
• Painful urination accompanied by fever—possible infection.
• Recent streptococcal throat infection, skin infection, or rash.

Diagnosis

Diagnosing nephritic syndrome involves a stepwise approach:

1. Medical History & Physical Exam

The clinician asks about recent infections, medication use, family history of kidney disease, and systemic symptoms (rash, joint pain, etc.). A blood pressure check and a careful examination for edema are essential.

2. Laboratory Tests

• Urinalysis – looks for red blood cells (often dysmorphic), red‑cell casts, protein, and sometimes casts of white cells or cylinders.
• Quantitative protein measurement – 24‑hour urine protein or spot urine protein/creatinine ratio.
• Blood tests – serum creatinine, BUN, electrolytes, complement levels (C3, C4), anti‑streptolysin O (ASO) titer, ANA, anti‑dsDNA, ANCA, anti‑GBM antibodies, hepatitis serologies.
• Complete blood count – to check for anemia or leukocytosis.

3. Imaging

• Renal ultrasound – assesses kidney size, echogenicity, and rules out obstruction.
• In select cases, CT or MRI may be used to evaluate renal vasculature.

4. Kidney Biopsy

When the cause is unclear or the disease is rapidly progressive, a percutaneous renal biopsy provides definitive histologic diagnosis and guides therapy. The sample is examined under light microscopy, immunofluorescence, and electron microscopy.²

Treatment Options

Treatment is tailored to the underlying cause, severity of kidney involvement, and presence of systemic disease.

General Measures

• Blood pressure control – ACE inhibitors or ARBs are first‑line; they reduce proteinuria and protect renal function.
• Low‑salt diet – 1500–2300 mg sodium/day to help control edema and hypertension.
• Fluid management – restriction may be needed if oliguria or pulmonary edema is present.
• Smoking cessation – improves overall cardiovascular and renal outcomes.

Cause‑Specific Therapies

• IgA Nephropathy – supportive care; steroids or immunosuppressants (e.g., cyclophosphamide, mycophenolate) are considered for progressive disease.
• Post‑streptococcal GN – usually self‑limited; treatment focuses on blood pressure control and diuretics for edema. Antibiotics eradicate the original streptococcal infection.
• Lupus nephritis – high‑dose corticosteroids plus immunosuppressants (mycophenolate mofetil, cyclophosphamide, or azathioprine). Hydroxychloroquine is continued for systemic disease.
• RPGN (e.g., anti‑GBM disease) – urgent plasmapheresis combined with high‑dose steroids and cyclophosphamide.
• MPGN – treat underlying cause (e.g., hepatitis C with antiviral therapy) and consider complement inhibitors (e.g., eculizumab) in select cases.
• Drug‑induced GN – discontinue the offending medication; most patients improve after removal of the trigger.
• Infection‑related GN (HIV, hepatitis) – antiviral therapy, plus standard renal protective measures.

Supportive Home Care

• Maintain adequate hydration (unless fluid‑restricted).
• Monitor blood pressure at home and keep a log for your provider.
• Track urine color and volume; report any change promptly.
• Follow a kidney‑friendly diet: limit protein to 0.8‑1 g/kg/day if advised by a dietitian.
• Adhere to scheduled laboratory follow‑ups to monitor kidney function.

Prevention Tips

While many causes are not fully preventable, several strategies reduce risk:

• Prompt treatment of streptococcal throat or skin infections; complete the full antibiotic course.
• Vaccinate against hepatitis B and maintain safe practices to avoid hepatitis C.
• Control systemic diseases such as diabetes, hypertension, and lupus aggressively.
• Avoid nephrotoxic drugs (NSAIDs, certain antibiotics) unless necessary; use the lowest effective dose.
• Practice good hand hygiene and avoid exposure to infections, especially in community settings.
• Stay hydrated and limit high‑protein or high‑salt meals if you already have chronic kidney disease.

Emergency Warning Signs

Sources:
1. Mayo Clinic. “Nephritic syndrome.” mayoclinic.org.
2. National Kidney Foundation. “Kidney Biopsy.” kidney.org.
3. KDIGO Clinical Practice Guideline for Glomerulonephritis, 2021.
4. CDC. “Strep throat and scarlet fever.” cdc.gov.
5. NIH National Institute of Diabetes and Digestive and Kidney Diseases. “IgA Nephropathy.” niddk.nih.gov.