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APRIL 2018 | Published by RCPA

Issue #079

Taking a detailed look at kidney disease through the electron microscope

Taking a detailed look at kidney disease through the electron microscope

In the 1970’s and 1980’s, the electron microscope had a very major diagnostic role in tumour diagnosis. Nowadays, that role has largely been replaced by alternative measures. As a result, the electron microscope is now almost wholly reserved for medical diagnostic problems in renal, muscle and other ultrastructural studies which include cilia analysis of the respiratory tract. In terms of the workload of the electron microscopy unit, renal biopsies account for approximately 80% of the unit’s workload.

Dr Julie Fletcher, Anatomical Pathologist, explains that there are four electron microscope units in New South Wales. Two machines are located at Concord General Hospital where she works.

“The unit at Concord takes referrals from a number of other institutions within New South Wales, elsewhere in Australia, New Zealand and some of the Pacific Islands. In addition to our unit, St Vincent’s Hospital, Westmead Hospital and Liverpool Hospital have electron microscopy units to process in-house hospital work.”

“With an electron microscope, we examine ultra-thin tissue sections stained with a heavy metal compound that allows the machine to focus an electron beam through the tissue. This provides high magnification, high resolution images at a subcellular or ultrastructural level. It is therefore quite a different form of tissue examination to the light microscope, allowing examination at a much higher level of detail.”

At Concord Hospital, Dr Fletcher explains that both machines are fully utilised supporting a busy diagnostic unit, where up to 80% of the workload is composed of renal biopsies. These biopsies include native kidney biopsies (when a patient’s own kidney is biopsied) or a transplant renal biopsy (a biopsy of a donor kidney transplanted into a recipient).

“Up to 80% of all kidney biopsies in Australia, or possibly even more, have electron microscopy studies as an integral part of the biopsy examination. In up to 30% of these cases, electron microscopy findings are either diagnostic beyond the light microscopy findings or add significantly to the light microscopy findings, thus influencing clinical treatment.”

“In the scenario of transplant biopsy examination, electron microscopy studies have become an integral part of the diagnostic classification for rejection of the graft (transplant), which is invaluable. Early diagnosis of graft rejection by electron microscopy can allow institution of added anti-rejection treatment and ultimately prolong the life of the graft. In Australia there is a very high referral rate of renal transplant biopsies for electron microscopy examination, which is possibly one of the reasons that Australia has one of the best overall renal graft survival rates globally.”

Dr Fletcher goes on to discuss the future of electron microscopy.

“Currently, there is no alternative technology available that has the degree of resolution that an electron microscope offers. For the foreseeable future, there are no alternative diagnostic tools that are going to fulfil this significant role in the diagnosis of the difficult cases which depend on EM to clarify the diagnosis.”

Dr Fletcher explains that the electron microscope is an expensive process and is labour intensive.

“In our institution, we are only able to charge about $180 for one of these cases and it costs us between $700 and $800 to actually examine one of the specimens. So we absorb the financial load for a lot of these referring institutions. The microscopes require specialised scientific staff to prepare biopsy material for examination, work both of the machines, recognise the ultrastructural changes and take the photographs. They require pathologists who have an understanding of electron microscopy to report the cases together with the scientific staff. Training in medical electron microscopy is not formal in any university, requiring training on the job training for all new personnel.”

“Replacement of a machine comes at a cost of around $700,000-$900,000. Fundraising and grants have contributed significantly to procurement of machines at Concord in the past. The availability of this important diagnostic test, which has a vital role in the diagnosis and evaluation of kidney disease in Australia, particularly for transplantation, should remain a priority for the Health Department.”

 


 

 

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