Blood tests are important to help diagnose lupus and to monitor its activity. There seem to be a lot but they can usually be done with just one blood or urine test, which is usually taken at each clinic visit.

These laboratory tests can include:

• Anti-nuclear antibody tests (ANA) - the ANA test is positive in almost all patients with lupus. However, it may be positive in many other illnesses, and therefore cannot be used to diagnose lupus on its own. If it is negative the diagnosis of lupus is far less likely.

• Anti-double-stranded DNA antibodies (dsDNA) - if positive, a diagnosis of lupus is very likely. An increase in dsDNA levels can be a signal of a flare.

• Extractable nuclear antigen antibodies (anti-ENA) - this is a group of tests, some of which can be indicators of lupus which can be linked to certain lupus symptoms.

• Serum Complement (C3 and C4) - a fall below normal levels often indicates a flare, as both C3 and C4 proteins are "used up" in active lupus.

• Erythrocyte Sedimentation Rate (ESR) - this test is raised by inflammation. It is not specific to lupus and can go up when you have various illnesses such as colds or flu.

• Full Blood Count (FBC) - this counts the number of cells in a sample of blood. The white blood cells, red blood cells and/or platelets can go down in lupus.

• Urine Test - this is an important test to check whether the kidneys are affected, as often kidney inflammation will not cause any noticeable symptoms. If the kidneys are inflamed, red bloods cells, and/or protein may be found when the lab tests your urine. There is not usually enough blood for your urine to look red. A urine sample will therefore be requested at each clinic visit.

• Other tests may only be carried out routinely every year. These may include levels of cholesterol and other antibodies (e.g. anti-cardiolipin antibodies) which can be abnormal in lupus, but importantly are treatable.