What is Kidney Biopsy?

Understanding Your Kidney Biopsy Results: A Guide for Newly Diagnosed Patients.

If you’ve recently been diagnosed with kidney disease, your doctor might have recommended a kidney biopsy to understand your disease better. Receiving the results of a biopsy can feel overwhelming, especially when faced with a new diagnosis which seems like medical jargon.

What is a Kidney Biopsy?

A kidney biopsy is a procedure in which a small piece of kidney tissue is removed and examined under a microscope. This helps doctors identify what is causing kidney problems, how much damage has occurred, and the best treatment options.

Key Sections of a Kidney Biopsy Report

When you receive your biopsy results, you may see several sections. Each part offers important insights into your kidney health:

1. Gross Description

This section provides a basic description of the tissue sample, including its size and color. While it doesn’t contain diagnostic information, it ensures that the sample is large enough for proper evaluation.

2. Light Microscopy (LM)

Light microscopy involves examining the kidney tissue under a regular microscope. Here are the key parts of the kidney that are checked:

• Glomeruli: These are tiny filtering units in your kidneys.

  • Normal: Healthy filtering structures.

  • Scarring or Sclerosis: Some of the glomeruli are damaged and have scar tissue, which can reduce kidney function and/or cause protein in urine.

  • Inflammation: If present, it could indicate an immune response causing damage.

• Tubules: These structures transport filtered fluid through the kidney.

  • Atrophy: This means the tubules have shrunk or been damaged, often due to long-standing kidney disease.

• Interstitium: This is the tissue surrounding the tubules.

  • Fibrosis: Fibrosis means scarring of the interstitial tissue, which can reduce how well your kidneys work.

• Blood Vessels: The report may mention thickening or narrowing of the blood vessels, which can affect blood flow to your kidneys.

3. Immunofluorescence (IF)

This test looks for immune deposits in the kidney tissue. Immune deposits occur when your immune system mistakenly attacks your kidneys. These deposits can be made up of antibodies or proteins. Here are some common findings:

• IgA, IgG, IgM: These are types of antibodies. For example, finding IgA deposits may indicate a condition called IgA nephropathy.

• C3, C4: These are proteins involved in your immune system. Their presence might suggest an autoimmune disease.

• Kappa and Lambda Light Chains: These proteins are part of normal antibodies but can be produced a lot in like multiple myeloma, a disease where abnormal proteins can damage the kidneys.

4. Electron Microscopy (EM)

Electron microscopy provides a highly detailed view with a magnification of 10,000X of your kidney tissue, showing tiny structures that regular microscopes can’t see. Here are a few things doctors look for:

• Podocyte Effacement: Podocytes are special cells that help filter your blood. Effacement means they’re damaged, which is common in diseases like minimal change disease (MCD) or focal segmental glomerulosclerosis (FSGS).

• Deposits: Electron-dense deposits can indicate the presence of immune complexes or abnormal proteins.

Common Terms You Might See

Here are some terms commonly found in biopsy reports and what they mean:

• Global vs. Segmental:

  • Global: The entire glomerulus is affected.

  • Segmental: Only part of the glomerulus is affected.

• Diffuse vs. Focal:

  • Diffuse: Most or all of the glomeruli are affected.

  • Focal: Only some glomeruli are affected.

• Proliferative: This means there are more cells than normal, often due to inflammation.

• Necrosis: Tissue death, indicating severe damage.

• Crescent Formation: This is a sign of severe injury to the glomeruli and is often seen in rapidly progressing kidney diseases.

How to Use This Information

Your biopsy results help your doctor:

• Identify the type of kidney disease you have (e.g., IgA nephropathy, lupus nephritis, or diabetic nephropathy).

• Determine whether your disease is active (inflammation) or chronic (scarring).

• Assess how much damage has already occurred.

• Decide on the best treatment plan for you.

Questions to Ask Your Doctor

When discussing your biopsy results, consider asking these questions:

1. What type of kidney disease do I have?

2. Is my kidney disease active or chronic?

3. How much permanent damage or scarring is present?

4. What are my treatment options?

5. How will this affect my kidney function in the long term?

Takeaway

Understanding your kidney biopsy report can help you feel more informed and empowered in managing your condition. While the medical terms may seem intimidating at first, your healthcare team is there to explain what they mean and guide you through your treatment options.

If you have specific questions or concerns about your results, don’t hesitate to contact your nephrologist—they’re your best resource for understanding your kidney health.