Kidney Biopsies: Indications, Techniques, and Importance in Diagnosing Glomerular Diseases

We have completed nearly 79 episodes so far, with a primary focus on chronic kidney disease (CKD)—its management, and raising awareness among the general public. Our goal has been to help people better understand kidney disease and improve its management. Now, we're starting a new journey, shifting our focus towards glomerular diseases and kidney transplants. However, before diving into these topics, it's crucial to understand one of the most important diagnostic procedures in nephrology: the kidney biopsy. A kidney biopsy is essential for diagnosing glomerular diseases, which makes it vital to grasp its significance before moving forward.

In this two-part series, I will first explain what a kidney biopsy is, including its indications, who should avoid it, and the associated risks. In the next episode, I will teach you how to interpret a kidney biopsy report.

Assalamualaikum, I am Dr. Vaseeka from Expert Consult Clinic of Lahore, speaking to you from our clinic studio. In our region, encompassing both Pakistan and India, kidney biopsies are still considered a major medical intervention, and many people avoid it due to fear. While some concerns are valid—especially if a biopsy is performed unnecessarily—a properly timed and accurately executed biopsy for the right patient is an invaluable diagnostic tool. A biopsy not only helps us avoid incorrect treatments but, when done correctly, can lead to proper treatment that may even cure the patient.

One of my favorite diagnostic tests following kidney disease screening is the kidney biopsy. This procedure allows for precise diagnosis, which is critical for treatment. To understand its value, let’s take a brief look at its historical background.

Historical Background of Kidney Biopsies

About 100 to 200 years ago, kidney biopsies were only performed surgically. Later, the development of needle biopsies, which we commonly use today, originated somewhat accidentally. A doctor performing a liver biopsy inadvertently inserted the needle into the kidney, leading to the realization that kidney tissue could also be biopsied using this method. Over the past 70 to 80 years, the kidney biopsy has become a well-established and highly effective diagnostic test, with significant improvements over time.

Modern Kidney Biopsy Techniques

Currently, there are three main techniques for performing a kidney biopsy. I will explain each one in detail:

1. Core Needle Biopsy: This is the most common method, performed in about 99% of cases. If you've had a kidney biopsy, it was likely done using this technique. It's widely accepted and easy to perform, with relatively few complications, which is why it's the preferred method globally.

2. Transjugular Biopsy: This technique involves accessing the kidney through a large vein in the neck (the jugular vein). It's used in cases where the patient has a horseshoe-shaped kidney or a high risk of bleeding. Research suggests that this method may reduce the risk of bleeding compared to the core needle biopsy. However, in practice, the reduction in bleeding risk isn't significant enough to make it the first choice. Moreover, not all hospitals or countries have experts skilled in performing transjugular biopsies.

3. Surgical Biopsy: This method is rarely used today. It's typically reserved for cases where the patient is already undergoing nephrectomy (kidney removal surgery) or when a small portion of the kidney needs to be removed due to a tumor, cyst, or other abnormalities. During surgery, the surgeon may save a small piece of tissue for biopsy. The only other scenario where a surgical biopsy might be considered is in a patient on a ventilator with acute kidney injury (AKI) that cannot be diagnosed by less invasive methods. However, in my 10-15 years of experience, I've rarely seen a surgical biopsy performed, especially in ventilated patients.

Indications for a Kidney Biopsy

Now, let’s discuss the indications—when a kidney biopsy is recommended:

1. Nephrotic-Range Proteinuria: The most important indication for a kidney biopsy is when a patient's urine shows a protein level exceeding 3 grams per day. This condition, known as nephrotic-range proteinuria, necessitates a biopsy to determine the underlying cause.

2. Acute Kidney Injury (AKI) of Unknown Origin: If a patient has AKI and the cause cannot be determined, and the condition does not improve within 7 to 14 days, a kidney biopsy is recommended. The biopsy may reveal glomerular disease, which can be treated, or tubular disease, which may have limited treatment options. In any case, a biopsy helps in making a proper diagnosis that could lead to timely treatment and potentially save the kidney.

3. Rapidly Worsening Chronic Kidney Disease (CKD): If a CKD patient, say in Stage 3, suddenly experiences a rapid increase in creatinine levels—going from 1.2 or 1.3 to 3 or 4 within weeks or months—a biopsy may be necessary, especially if no obvious cause for AKI is found. This could help identify an underlying condition that requires urgent treatment.

4. Microscopic Hematuria: The presence of blood cells in urine visible only under a microscope can indicate a glomerular origin, suggesting possible glomerular disease. In such cases, a kidney biopsy is clearly indicated to determine the exact cause.

5. Unexplained Worsening of Diabetic Kidney Disease: If a diabetic patient with stable kidney function and proteinuria suddenly experiences a significant increase in proteinuria, it may indicate the development of a new disease in addition to the existing diabetic kidney disease. A biopsy is crucial in such cases to make the correct diagnosis and initiate appropriate treatment.

Doubtful Cases and Discussions Between Doctor and Patient

In some cases, the decision to perform a kidney biopsy is not straightforward and requires a detailed discussion between the doctor and the patient. Recently, I discussed a case where the patient had mild proteinuria (around 500 to 1000 mg/day) with normal kidney function. In such situations, there are two possible approaches:

1. Close Monitoring: The patient can be closely monitored with monthly checks of creatinine and urine protein levels while optimizing treatment. If kidney function remains stable and proteinuria does not increase, a biopsy may not be necessary.

2. Biopsy for Definitive Diagnosis: If proteinuria worsens or if the patient prefers a definitive diagnosis, a biopsy might be recommended to ensure that no underlying disease is missed.

Repeat Kidney Biopsies

Typically, repeat kidney biopsies are not performed after initial treatment. However, there are two specific situations where repeat biopsies might be recommended:

1. Transplant Cases: The frequency of repeat biopsies can vary between transplant programs. Some nephrologists or transplant surgeons advocate for frequent biopsies of the transplanted kidney, as it is easier to biopsy compared to the native kidney.

2. Worsening Condition Post-Treatment: In cases where the patient’s condition worsens after initial treatment, a repeat biopsy may be considered to reassess the situation and adjust the treatment plan accordingly.