Hi I am Dr Mittal. I have read your message. I think I can help you. First, a package test means that multiple tests are included that correlate to the test. CPK and SPE can both be package tests as there are many related tests needed in a diagnosis. The symptoms that you seem to be facing as per the query is basically severe backache that increases on lying down or bending- in other words, anything that causes the spine to be under pressure. Now SLE itself can cause the symptoms. The muscles and bone problems can arise in SLE itself and thus possibly one will feel that there is nothing more to do. However, in many situations, the doctors may get biased my a diagnosis. So, I think it is good that your doctor did not get biased with your pre existing diagnosis of SLE and continued to look for other causes of backache. A severe backache can happen due to muscle disorders, a condition known as myopathy. The cause of myopathy may be SLE itself. The test commonly done to test myopathy is CPK or creatine phosphokinase. This is a test done from blood. The idea is if the CPK is raised, it suggests myopathy. In this situation, your doctor will need to modify the therapy. I am unaware of your medication from the query. So I cannot really comment upon it. But some medicines themselves cause myopathy. And sometimes, the dose of existing medicines need to be stepped up for treatment of myopathy. So I presume your doctor wanted to check that. Second test was SPE or serum protein electrophoresis. This is one of the tests for multiple myeloma. This is a type of malignancy that affects the bones and causes bone pains and should be ruled out in middle aged to elderly commonly if the backache is worsening and is specially bad when lying down. If the test is negative, there is nothing to worry about. If it does come out to be positive, multiple myeloma can be treated. So again you need not worry since the treatment is available. Why the doctor did not tell you about the tests is something I can only speculate about. I guess it was because these are just doubts, considering you already have SLE- in medicine, the usual dictum is that one disease can explain the symptom, the other condition should not be sought. Having said that, its a folly to miss another diagnosis due to a pre existing condition. I think he would have told you if the tests came out positive. So there should be nothing to worry about- the doctor was just making sure that there is no other problem. Possibly since there was nothing else diagnosed, he did not tell you about it. I have tried to make it as simple as possible to understand the situation. in case there are still doubts, feel free to contact me for further details. Best of luck, Dr Mittal