Yes, nephrotic syndrome is frequently caused by other underlying health conditions that damage the kidneys’ filtering units. When the syndrome is a result of another disease elsewhere in the body, it is referred to as ‘secondary nephrotic syndrome’. In the UK, systemic conditions like diabetes and autoimmune diseases such as lupus are among the most common reasons adults develop this type of kidney protein leak.
Secondary nephrotic syndrome occurs because chronic illnesses can cause long-term inflammation or structural changes to the glomeruli (the tiny filters in the kidneys). Unlike primary causes that start within the kidney itself, secondary causes require a dual treatment approach: managing the protein leak and strictly controlling the parent condition. Identifying these links is a vital part of NHS diagnostic pathways, as it ensures that the root cause such as high blood sugar or an overactive immune system is addressed to prevent permanent kidney scarring.
What We’ll Discuss in This Article
- The mechanism of how systemic diseases damage kidney filters.
- Detailed look at diabetic nephropathy and its role in protein leakage.
- How autoimmune conditions like lupus and vasculitis affect the kidneys.
- Other secondary factors, including infections and certain medications.
- Differences in managing primary versus secondary nephrotic syndrome.
- The importance of regular screening for high-risk patients.
Diabetes as a cause of nephrotic syndrome
Diabetes is the leading cause of secondary nephrotic syndrome in adults within the UK. Over time, high levels of glucose in the blood can damage the small, delicate blood vessels inside the kidneys. This process, known as diabetic nephropathy, causes the filters to become ‘leaky’, allowing albumin to escape into the urine.
Initially, this may only cause tiny amounts of protein to leak (microalbuminuria), but if left unmanaged, it can progress to full-blown nephrotic syndrome. Patients with both Type 1 and Type 2 diabetes are at risk, particularly those who have had the condition for many years or those with poorly controlled blood pressure.
Clinical Context
NICE guidelines recommend that all patients with diabetes undergo annual urine and blood tests to check their albumin-to-creatinine ratio (ACR). Early detection of protein in the urine allows doctors to prescribe ACE inhibitors or ARBs, which can slow down kidney damage and prevent the onset of nephrotic syndrome.
Autoimmune diseases and kidney damage
Autoimmune diseases occur when the body’s immune system mistakenly attacks its own healthy tissues. When this attack targets the glomeruli, it can lead to severe inflammation and nephrotic syndrome.
The most common autoimmune causes include:
- Systemic Lupus Erythematosus (SLE): This condition often leads to ‘lupus nephritis’, where immune complexes build up in the kidney filters, causing them to leak massive amounts of protein.
- Vasculitis: Conditions that cause inflammation of the blood vessels can reduce blood flow to the kidneys and damage the filtration barrier.
- Sjögren’s Syndrome: Though less common, this can occasionally involve the kidneys and lead to secondary glomerular issues.
In these cases, the treatment often involves powerful immunosuppressant medications to ‘calm’ the immune system and stop it from further damaging the kidneys.
Other secondary causes and triggers
Beyond diabetes and autoimmune disorders, several other systemic issues or external factors can lead to the development of nephrotic syndrome.
- Infections: Certain viral infections like Hepatitis B, Hepatitis C, and HIV are known to trigger changes in the kidney filters.
- Amyloidosis: This is a rare condition where abnormal proteins (amyloids) are deposited in organs, including the kidneys, disrupting their structure and function.
- Cancers: Some types of cancer, such as lymphoma or leukaemia, can sometimes present with nephrotic syndrome as a ‘paraneoplastic’ symptom.
- Medications: Long-term use of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), such as ibuprofen, has been linked to kidney filter damage in sensitive individuals.
| Category | Specific Condition | Mechanism |
| Metabolic | Diabetes Mellitus | High sugar damages blood vessel walls |
| Autoimmune | Lupus (SLE) | Immune complexes cause inflammation |
| Infectious | Hepatitis B/C | Viral trigger of immune-mediated damage |
| Protein-related | Amyloidosis | Abnormal protein deposits in filters |
Primary vs. Secondary Nephrotic Syndrome
It is crucial for clinicians to differentiate between primary and secondary causes, as the long-term outlook and treatment strategies differ significantly.
| Feature | Primary Nephrotic Syndrome | Secondary Nephrotic Syndrome |
| Origin | Starts in the kidney itself | Starts as a systemic disease |
| Common Example | Minimal Change Disease | Diabetic Nephropathy |
| Diagnostic Key | Often requires kidney biopsy | Often diagnosed via blood/history |
| Treatment Focus | Steroids / Immunosuppressants | Managing the underlying disease |
| Age Group | More common in children | More common in adults |
Nephrotic vs. Nephritic Syndrome in Systemic Disease
Some systemic diseases, like lupus, can cause both nephrotic and nephritic features. Doctors must determine which ‘pattern’ is dominant to provide the right care.
- Nephrotic Pattern: Heavy protein loss, significant swelling, and high cholesterol. Often seen in diabetic patients.
- Nephritic Pattern: Blood in the urine, high blood pressure, and decreased urine output. Often seen in acute autoimmune flare-ups.
To Summarise
Nephrotic syndrome is frequently caused by other conditions like diabetes and autoimmune diseases. These systemic illnesses damage the kidneys’ filters over time, leading to significant protein loss and swelling. Managing the underlying disease is the most important step in treating secondary nephrotic syndrome. Regular screening and early intervention are essential for those with chronic conditions to prevent the progression to permanent kidney damage.
If you experience severe, sudden, or worsening symptoms, such as significant difficulty breathing or extreme facial swelling, call 999 immediately.
Can type 2 diabetes cause nephrotic syndrome?
Yes, it is one of the most common causes of secondary nephrotic syndrome in adults, usually developing after several years of living with the condition.
Will my kidneys get better if my lupus is treated?
In many cases, treating the underlying lupus with immunosuppressants can significantly reduce the protein leak and improve kidney function.
Can an infection cause my kidneys to leak protein?
Yes, certain viruses like Hepatitis or HIV can trigger the kidneys to leak protein, leading to nephrotic-range symptoms.
Is secondary nephrotic syndrome more serious than primary?
It isn’t necessarily more serious, but it is often more complex to manage because two or more health conditions must be treated at the same time.
Are children at risk of secondary nephrotic syndrome?
While possible, secondary causes are much rarer in children; their cases are almost always primary, such as Minimal Change Disease.
Can I prevent secondary nephrotic syndrome?
The best way to prevent it is to maintain good control of your blood sugar, blood pressure, and any autoimmune conditions you may have.
Authority Snapshot
This article was reviewed by Dr. Stefan Petrov, a UK-trained physician with experience in general medicine and emergency care. The information aligns with NHS and NICE clinical guidance regarding the management of secondary glomerular diseases. Our goal is to explain how systemic health impacts kidney function and why managing primary illnesses is crucial for long-term renal health.
