What is a renal (kidney) biopsy?
A renal (kidney) biopsy is a medical procedure that collects a tissue sample from the kidney so it can be examined under a microscope. It can provide doctors with a comprehensive understanding of a patient’s kidney disease and the best treatment.
Reasons to do a kidney biopsy include blood or protein found in the urine; abnormal blood test results; acute or chronic kidney disease with no clear cause; nephrotic syndrome and other glomerular disease (which happens when the filtering units of the kidney are damaged).
Dr Jonathan Zwi, Histopathology Department, LabPLUS in Auckland, explains that nearly all kidney biopsies are percutaneous (through the skin).
“A needle is placed through the skin and is guided to the right place in the kidney, usually with the help of an ultrasound” says Dr Zwi.
A kidney biopsy can assess a patient’s type of kidney disease, what caused the disease, how severe it is, what treatment is necessary, whether it might run in the family, if the disease is getting better or worse with treatment, and why a transplanted kidney is not working well. A kidney biopsy can also help to identify lesions seen on imaging, which could be cysts or benign or malignant tumours.
Dr Zwi explains that pathology plays a crucial role not only in the diagnosis of kidney disease, but also in the recommendation of therapies and subsequent monitoring.
“Part of what we do here is not only diagnosing the condition but also grading the severity of it. We assess how much permanent damage is present in the kidney, for example scarring. If the kidney is too scarred then, even if you’ve got the diagnosis, it may not be worth treating. If the disease has significantly and permanently damaged the kidney, then a transplant is necessary.
“After a transplant, biopsies are also done at set times to monitor the progress, but also at any time if the kidney starts to not function properly. A biopsy is done to see if there is rejection or a viral disease of the kidney, which can happen in immunocompromised patients. That evaluation very much guides the therapies of a patient, particularly anti-rejection therapy.”
Dr Zwi says that, in addition to biopsies, blood tests offer further insights in relation to the cause of the disease. As well as the more common causes of kidney disease, such as diabetes and high blood pressure, a number of other factors can affect the glomerulus, which is the kidney’s filtering unit.
“Quite often, kidney disease is diagnosed as a result of a blood or urine test. The laboratory plays a crucial role in picking up blood and or protein that may be present in the urine. Sometimes the disease is identified quite late when patients are really presenting renal failure with anaemia and lethargy,” says Dr Zwi.
“Blood tests are used to determine some of the main causes of renal impairment. For example, a blood test may identify lupus (systemic lupus erythematosus), which is an auto-immune disease that is quite common in causing renal impairment, or diabetic renal disease. Other diseases that could be identified include, post infectious glomerulonephritis, which usually occurs in children after a sore throat or skin infection with streptococci, and IgA nephropathy, which is a primary disease of the kidney. There are also diseases that are a consequence of treatment with medications. These are quite important to diagnose because, if caught early, they are treatable. The role of the laboratory is crucial in diagnosing and monitoring kidney disease, offering a range of information in order to treat the patient effectively,” says Dr Zwi.
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This article appeared in the April 2018 Edition of ePathWay which is an online magazine produced by the Royal College of Pathologists of Australasia (http://www.rcpa.edu.au/Library/Publications/ePathway).
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