Glomerulonephritis (blood in urine) - Causes, Treatment & When to See a Doctor

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What is Glomerulonephritis (blood in urine)?

Glomerulonephritis (GN) refers to inflammation of the glomeruli – the tiny filtering units inside each kidney that remove waste and excess fluid from the blood. When the glomeruli become inflamed, they lose their ability to filter properly, allowing red blood cells, protein, and sometimes pus to leak into the urine. The presence of visible blood in the urine (hematuria) or microscopic blood detected on a urine test is a hallmark sign of many forms of GN.

Glomerulonephritis can be acute (developing quickly over days‑weeks) or chronic (persisting for months‑years). Some cases are self‑limited and resolve with treatment, while others may progress to chronic kidney disease (CKD) or end‑stage renal disease (ESRD) if not recognized early.

Common Causes

Inflammation of the glomeruli can be triggered by a wide range of conditions. The most frequent causes include:

• Post‑infectious GN – follows streptococcal throat or skin infections.
• IgA nephropathy (Berger disease) – deposition of immunoglobulin A in the glomeruli.
• Membranous nephropathy – immune complex deposits on the glomerular basement membrane.
• Rapidly progressive GN (RPGN) – aggressive inflammation that can lead to kidney failure within weeks.
• Lupus nephritis – systemic lupus erythematosus affecting the kidneys.
• ANCA‑associated vasculitis (e.g., granulomatosis with polyangiitis, microscopic polyangiitis).
• Goodpasture syndrome – antibodies attack both the kidneys and lungs.
• Infective endocarditis – bacterial infection of heart valves can cause immune‑complex GN.
• Hereditary diseases – Alport syndrome, thin‑basement‑membrane disease.
• Drug‑induced GN – NSAIDs, penicillamine, gold salts, or certain antibiotics.

Rarely, GN can be a manifestation of malignancy, HIV infection, or hepatitis B/C.

Associated Symptoms

Blood in the urine is often the first clue, but many patients experience additional “nephritic” or “nephrotic” features:

Nephritic‑type signs (inflammation‑dominant)

• Dark, cola‑colored or smoky urine (gross hematuria).
• Swelling (edema) of the face, hands, feet, or ankles.
• Reduced urine output (oliguria) or feeling of incomplete bladder emptying.
• High blood pressure (hypertension).
• Painful or tender kidneys on examination.
• Fever, malaise, or recent sore throat/skin infection.

Nephrotic‑type signs (protein‑leak dominant)

• Foamy or frothy urine (proteinuria).
• Marked swelling especially around the eyes and abdomen.
• Weight gain from fluid retention.
• High cholesterol and triglyceride levels.

When to See a Doctor

Because GN can progress quickly, early medical evaluation is essential. Seek care promptly if you notice:

• Visible blood in the urine (pink, red, or brown urine).
• Persistent dark urine that does not clear after hydration.
• Swelling of the face, hands, or feet that worsens over a few days.
• Sudden rise in blood pressure or headache.
• Painful urination accompanied by fever or back pain.
• Reduced urine output (< 400 mL/day) or feeling that you cannot fully empty your bladder.

If any of these occur, especially after a recent infection, schedule a medical appointment within 24‑48 hours.

Diagnosis

Diagnosing GN requires a combination of history, physical examination, laboratory testing, and imaging.

1. Urine Tests

• Urinalysis – looks for red blood cells, casts, protein, and white cells.
• Urine microscopy – identifies dysmorphic red cells (indicating glomerular origin) and red‑cell casts.
• Protein quantification – 24‑hour urine protein or spot urine protein‑to‑creatinine ratio.

2. Blood Tests

• Serum creatinine & eGFR – gauge kidney function.
• Blood urea nitrogen (BUN).
• Complement levels (C3, C4) – often low in post‑infectious, lupus, or membranoproliferative GN.
• Auto‑antibodies: ANA, anti‑dsDNA (lupus), ANCA, anti‑GBM (Goodpasture).
• Serologies for hepatitis B/C, HIV, and streptococcal antibodies (ASO titer).

3. Imaging

• Renal ultrasound – assesses kidney size, obstruction, or chronic scarring.
• CT or MRI – rarely needed unless complexities such as renal masses are suspected.

4. Kidney Biopsy

Considered the gold standard when the cause is unclear or when rapid progression is suspected. A tiny core of kidney tissue is examined under a microscope to identify the specific pattern of inflammation, immune deposits, and degree of scarring. Results guide targeted therapy (e.g., steroids, immunosuppressants, plasmapheresis).

Treatment Options

Treatment is tailored to the underlying cause, severity of kidney involvement, and patient factors.

1. General Measures

• Blood pressure control – ACE inhibitors or ARBs are first‑line; they lower intraglomerular pressure and reduce protein loss.
• Fluid and sodium restriction – 2 g of sodium per day and fluid intake limited to 1.5–2 L/day if edema is present.
• Dietary protein moderation – 0.8 g/kg/day (unless on dialysis).
• Quit smoking and limit alcohol, both of which exacerbate kidney damage.

2. Specific Medical Therapies

• Corticosteroids (prednisone, methylprednisolone) – reduce inflammation in many immune‑mediated GNs.
• Immunosuppressive agents – cyclophosphamide, mycophenolate mofetil, azathioprine, or rituximab based on disease type.
• Plasmapheresis – used in rapidly progressive GN, Goodpasture syndrome, or severe ANCA‑vasculitis.
• Antibiotics – indicated for post‑infectious GN (to eradicate residual streptococcal infection) or for underlying infections.
• Antimalarial drugs – hydroxychloroquine for lupus nephritis.
• Supportive therapy for nephrotic syndrome – statins for hyperlipidemia, diuretics for edema, and anticoagulation if high clot risk.

3. Home / Self‑Care Measures

• Maintain a hydration target of 1.5–2 L of plain water per day unless fluid restriction is ordered.
• Monitor blood pressure at home; aim for <130/80 mmHg unless your doctor advises otherwise.
• Track urine color daily; note any new pink or brown hues.
• Adopt a kidney‑friendly diet: limit processed foods, choose fresh fruits/vegetables, avoid high‑potassium items (bananas, oranges) if hyperkalemia develops.
• Keep a medication list and discuss any over‑the‑counter NSAIDs, herbal supplements, or “protein powders” with your provider.

Prevention Tips

While not all forms of GN are preventable, several strategies lower risk or reduce recurrence:

• Prompt treatment of streptococcal throat or skin infections – complete the full course of prescribed antibiotics.
• Control chronic diseases – keep diabetes and hypertension well‑managed.
• Avoid unnecessary NSAIDs and nephrotoxic drugs – especially in people with prior kidney injury.
• Vaccinations – flu, pneumococcal, hepatitis B, and COVID‑19 vaccines reduce infection‑related GN triggers.
• Regular health check‑ups – annual urine dipstick screening for high‑risk individuals (those with lupus, vasculitis, or a family history of kidney disease).
• Safe sex practices – reduce risk of hepatitis B/C and HIV, which can cause GN.
• Healthy lifestyle – balanced diet, regular exercise, and weight control maintain overall vascular health and kidney perfusion.

Emergency Warning Signs

These symptoms require immediate medical attention (call 911 or go to the nearest emergency department):

• Sudden inability to urinate or a dramatic decrease in urine output.
• Severe flank or abdominal pain accompanied by vomiting.
• Rapidly rising blood pressure (>180/120 mmHg) with headache, visual changes, or confusion.
• Sudden, massive hematuria (bright red urine or clots).
• Shortness of breath, chest pain, or coughing up blood (possible Goodpasture syndrome).
• Signs of fluid overload: severe swelling, rapid weight gain (>2 kg in 24 h), or difficulty breathing.

Key Take‑aways

Glomerulonephritis is an inflammation of the kidney’s filtering units that often presents with blood in the urine. A wide variety of infections, autoimmune diseases, and drugs can trigger it. Early recognition, prompt laboratory work‑up, and targeted therapy are essential to preserve kidney function. Patients should monitor urine color, blood pressure, and swelling, and seek urgent care if any emergency warning signs appear. With appropriate treatment and preventive measures, many individuals achieve remission and maintain healthy kidneys.

References:

• Mayo Clinic. “Glomerulonephritis.” https://www.mayoclinic.org
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). “Glomerular Diseases.” https://www.niddk.nih.gov
• Cleveland Clinic. “Hematuria (Blood in Urine).” https://my.clevelandclinic.org
• American College of Rheumatology. “ANCA‑Associated Vasculitis.” https://www.rheumatology.org
• Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for Glomerulonephritis. 2022.

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