Proteinuria

What is proteinuria?

The kidneys filter the blood continuously, removing waste while retaining essential proteins that the body needs. Healthy kidneys keep virtually all protein in the bloodstream. Proteinuria occurs when the kidney's filtering units become damaged or inflamed, allowing protein (primarily albumin) to leak through into the urine.

A small amount of protein in urine is normal. Proteinuria is defined as protein excretion consistently above 150 mg per day. It is classified by severity:

• Microalbuminuria is a mild but clinically important elevation in urinary albumin, often the earliest detectable sign of kidney damage in diabetes and hypertension.

• Macroalbuminuria reflects more significant kidney damage and is associated with progressive kidney function decline.

• Nephrotic range proteinuria above 3.5 g per day indicates severe glomerular damage and is associated with marked fluid retention, low albumin, and high cholesterol.

Proteinuria is not a disease in itself but a marker of an underlying condition affecting the kidneys. Identifying the cause is as important as identifying the proteinuria.

Symptoms of proteinuria

Mild proteinuria typically causes no symptoms and is detected only through laboratory testing. As protein loss increases, symptoms may include:

• Foamy or frothy urine, caused by albumin reducing the surface tension of urine

• Swelling in the ankles, feet, or around the eyes from fluid retention as blood albumin falls

• Persistent fatigue and weakness

• Reduced urine output in advanced cases

• In nephrotic syndrome: severe swelling, weight gain from fluid retention, and increased infection risk from loss of immune proteins

What causes proteinuria?

Proteinuria results from damage to the glomeruli, the tiny filtering units within the kidneys. Common contributing causes include:

• Diabetes is the most common cause worldwide. Persistently high blood sugar damages glomerular capillaries, causing progressive protein leakage. Microalbuminuria is the earliest detectable sign of diabetic kidney disease.

• Hypertension increases pressure within the glomeruli, causing mechanical damage to the filtering membrane over time.

• Glomerulonephritis is inflammation of the glomeruli from immune-mediated conditions including IgA nephropathy, lupus nephritis, and post-infectious glomerulonephritis.

• Pre-eclampsia causes proteinuria during pregnancy as a consequence of placental dysfunction and endothelial damage.

• Medications including non-steroidal anti-inflammatory drugs, certain antibiotics, and contrast agents can cause transient or persistent proteinuria.

• Multiple myeloma causes a specific form of proteinuria from overflow of immunoglobulin light chains (Bence Jones protein).

• Transient causes including strenuous exercise, fever, dehydration, and standing for prolonged periods can cause temporary proteinuria that resolves at rest.

How is proteinuria detected?

Proteinuria is primarily detected through urine testing, supported by blood tests assessing kidney function and the underlying conditions driving glomerular damage.

Blood tests Elfcare's panel includes the key markers for assessing kidney health and the conditions most closely associated with proteinuria:

• Creatinine, cystatin C, and eGFR assess kidney filtering capacity. Proteinuria and reduced eGFR together indicate more advanced kidney disease than either alone.

• Albumin reflects both nutritional status and protein loss. Low serum albumin in the context of proteinuria indicates significant ongoing protein loss.

• HbA1c and glucose assess blood sugar control, the leading cause of proteinuria worldwide.

• Total cholesterol, LDL, and triglycerides are elevated in nephrotic syndrome as the liver overproduces lipoproteins to compensate for low albumin.

• CRP reflects systemic inflammation driving glomerular damage in immune-mediated conditions.

• Electrolytes including sodium and potassium assess the kidneys' regulatory function alongside protein handling.

• Calcium and phosphate become dysregulated as kidney disease progresses.

Abdominal MRI Elfcare's full body MRI images both kidneys directly, identifying structural changes including cortical thinning, scarring, asymmetry, and any masses that may be contributing to abnormal kidney function. While urine testing is the primary tool for detecting proteinuria itself, MRI provides essential structural context.

Why early detection matters

Proteinuria detected at the microalbuminuria stage is the earliest opportunity to intervene in diabetic and hypertensive kidney disease, when the damage is still largely reversible with tight blood pressure and blood sugar control. Left untreated, proteinuria predicts progressive kidney function decline, cardiovascular disease, and ultimately kidney failure requiring dialysis. It is also a systemic risk marker, as even mild proteinuria significantly raises cardiovascular mortality independent of kidney function. Identifying the underlying cause and treating it aggressively at the earliest stage is the most effective way to preserve long-term kidney and cardiovascular health.

How Elfcare can help

Elfcare's blood panel covers a comprehensive kidney health profile including eGFR, cystatin C, albumin, HbA1c, lipids, and metabolic markers, providing a detailed picture of kidney function and the conditions most commonly driving proteinuria.

Our abdominal MRI images both kidneys directly, providing the structural assessment that blood tests alone cannot give.

If your results suggest a potential issue, we coordinate the necessary follow-up, such as a urine albumin-to-creatinine ratio (uACR) test, to confirm proteinuria. From there, we manage further diagnostics or refer you directly to the appropriate specialist to ensure a clear path for your treatment and recovery.