Understanding tests

Tests before, during and after treatment are primarily designed to do two things to see whether the treatment is working and to make sure that there are no side effects so severe that it is necessary to reduce the dosage or even discontinue treatment completely. This section looks at the key tests in relation to treatment and how they are interpreted.

NICE guidelines on who is eligable for treatment changed in August 2006 to include people with mild to moderate disease. This means it is no longer necessary for consultants to order a liver biopsy to check that the disease is in the moderate to severe category, however a biopsy may be needed for other reasons.

The biopsy will show inflammation and scarring. Inflammation is the indication of the ongoing assault on the liver and is most commonly measured on the Ishak scale of 0 to 18, where 0 is none and 18 is the maximum. Scarring is the result of past damage to the liver and is usually measured either on the Ishak scale of 0 to 6, whre 0 represents no scarring and 6 cirrhosis, the Metavir scale of 0 to 4, where 0 represents no scarring and 4 cirrhosis, or on the Knodell scale of 0 to 6, where 0 is no scarring and 6 cirrhosis. In between no scarring and cirrhosis the numbers measure the degree of fibrosis, higher numbers meaning more fibrosis.

A pre-treatment biopsy may be useful for comparing against a biopsy some time after treatment has finished because interferon can cause a reversal in both inflammation and scarring.

A genotype test is the basis for deciding the length of treatment.

• Types 2 and 3 are recommended to do treatment for 24 weeks
• Types 1,4, 5 and 6 are recommended to do treatment for 48 weeks

A liver function test measures a whole range of the livers functions, all of which bear to some degree on the health of the liver. During treatment particular attention is paid to the AST and ALT levels. These are generally above normal in people with hepatitis C and are expected to return into the normal range (0-40) if treatment works. An early fall towards normal levels, within the first 3 months, is a good sign but normalisation may not occur until after treatment has finished.

3 indicators are closely monitored, as very low levels are dangerous. If they get too low, the dose may have to be cut or treatment stopped altogether :

• Haemoglobin, which is required to transport oxygen around the body. Ribavirin can cause levels to fall.
• Platelets, which are required for blood clotting. Interferon can reduce levels.
• Neutrophils, which are part of white blood cells and fight infection. Interferon can lower levels.

A thyroid function test is used to check for thyroid disease. This can be either an overactive or an underactive thyroid (hyperthyroidism or hypothyroidism). Your thyroid gland secretes hormones that regulate growth and development by controlling your metabolism. Hyperthyroidism increases your metabolism whereas hypothyroidism decreases it. These are measured by the relative levels of thyroid stimulating hormone and thyroxin. The test will also measure whether you have any thyroid antibodies, which could indicate a tendency to develop thyroid disease, which can occasionally be caused by interferon.

Because of the dangers of ribavirin to foetuses in the womb, pregnancy tests are required before treatment starts (if you are pregnant, you cannot start treatment) and regularly throughout.

A quantitative PCR test will measure the amount of virus in your blood. This is measured before treatment starts to determine a reference or baseline level. A follow-up test will be performed after 6 months, although sometimes after 3 months. If treatment is working, you should expect to see at least a hundred-fold drop (often referred to as a 2 log drop) in your viral load. So, if you started treatment with a viral load of 2 million parts per mil, you should expect to see it drop to 20,000 or lower, certainly less than 100,000.

This is the test that shows whether the virus can be detected at all. If it remains undetectable 6 months after you have finished treatment, then it has been successful.