What Tests Mean


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Dr Pram Mistry and Susie Noe facilitated this important session at the March 1998 Workshop in London. Interest was high. David Lewis reports.

Dr Mistry said that tests were needed for diagnosis and to see whether a patient needed treatment. They were also needed to monitor treatment. He said that he likes to see patients on therapy every two to three months and those not on therapy every six months.

Blood Tests

Some of the most important tests are performed in the laboratory using one blood sample. These provide a useful way to monitor progression of the disease and its response to enzyme treatment. Measurement of haemo-globin and platelets reflect function of bone marrow as well as the degree of enlargment of the spleen.

There are a number of markers of disease acitivity, for example acid phosphatase, angiotensin converting enzyme activity and blood cholesterol.

The recent discovery of the enzyme chitotriosidase by Dr Hans Aerts and his group in Amsterdam has provided a useful indicator of assessing the total body cellular burden of Gauchers cells in the form of chitotriosidase activity in blood.

In our clinic we perform this test every three months. Serial measurements are useful for following progression of Gauchers disease and 'fine-tuning' enzyme treatment.

The normal level of chitotrisidase is less than 150; in some patients the levels can exceed 25,000. After two to four years of enzyme therapy, the levels of chitotriosidase can drop to less than 500.

This test is now available at all designated centres in the UK and form part of the national database that is being compiled at present.'

Dr Mistry said that he thought it unlikely that a patient could stop enzyme replacement therapy altogether but the dose could be reduced and possibly given as infrequently as once a month.

X rays and CT Scans

X rays are needed to determine bone fractures and specific bone pain,' explained Dr Mistry. 'CT scans assist in evaluating involvement of the liver and spleen; a modification of this technique can also help assess the bones.'

MRI Scans

This is used for imaging the spleen and liver. The advantages of MRI (magnetic resonance imaging) is there is no radiation and it can assess liver, spleen and bone marrow at the same time. However some patients cannot tolerate the closed space in the scanner and the noise during scanning .

Its use for imaging the bones is more problematical as there can be false readings - one member in the audience reported a false reading of a malignant tumour in his wifeµs spine.

Ultrasound

Similar false readings can arise with ultrasound. Dr Mistry said that ultra-sound was a reliable way of measuring spleen and liver size but had the draw-back that it makes infarcts look like tumours which can lead to inapprop-riate tests and alarm the patient.

Liver biopsy

This test would be called for where a patient has abnormal liver function tests which are inconsistent with his general condition. However it was a dangerous procedure which should only be done when clearly indicated.

A liver biopsy can be hazardous because of a low platelet count and frequent occurance of abnormal clotting,' warned Dr Mistry.

A form of haemophilia, factor XI deficiency, may also be present in some patients with Gauchers disease. Thus extreme care has to be exercised in performing liver biopsy.

An alternative method is by the transjugular route which requires expertise available only in major liver centres.

Bone Marrow Aspiration

Dr Mistry thought there were very few indications where this should be used.

Screening

Dr Mistry said he was against mass screenings, even among the Jewish community because two thirds of those of Ashkenazi ancestry, who have the disease, never have any symptoms.


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Source: Gauchers News July 1998

© Copyright Gauchers Association 1998