When a doctor orders blood tests to determine whether a patient has lupus, levels of white cells, red cells and certain immune-related proteins are all carefully scrutinized. It is vital that more than one test be performed, to verify that the disease really is lupus, but also to identify the type and severity, and if possible, the areas that are currently suffering damage. Because lupus is an autoimmune disorder that can affect any part of the body, it often looks like other kinds of disease, making it difficult to diagnose – and a wrong diagnosis means the patient is given the wrong treatment.
The American College of Rheumatology (ACR) has created a list of eleven symptoms that are typical of lupus; the rule of thumb is that any four symptoms in combination indicate the patient has the disease. Some of these symptoms, such as joint pain, fever, a prominent facial rash or headaches, are things the patient can feel and describe to the doctor. However, other symptoms – such as protein in the urine or unusually high numbers of immune cells – can only be discovered through medical testing, and are sometimes the only warning that lupus has injured the body enough to cause the development of a secondary disease.
The Immune System and Lupus CRP Levels
The immune system is a complex set of chemical checks and balances, set in motion when a foreign microorganism enters the body. Each cell in a person’s body has protein “markers” that translate as “self” to the immune system. Foreign invaders don’t have those markers; when they appear, several types of immune cells activate in a specific sequence, protecting the surrounding tissues, creating antibodies to target the invader and even storing a “memory” of the microorganism so the immune system will respond more efficiently, should it encounter the invader again.
The immune system has other cells that cause tissue inflammation – that isn’t necessarily a bad thing. Inflammation causes tissues to swell, containing the injury or infection to one area, rather than allowing it to spread. This reaction happens right at the beginning of the immune response, just as the immune cells start producing antibodies. The agents that begin, sustain and shut off the immune response are a series of proteins made in the liver, called C-Reactive Proteins, or CRP.
C-reactive proteins work a bit like dominoes. One protein activates a process that alerts a second protein, which activates a third, and so on. This chain of inter-dependant proteins is called the “complement system.” Low levels of certain complement proteins is one of the eleven lupus indicators as defined by the ACR.
Testing for CRP
The main reason to test complement levels in lupus patients is to determine whether inflammation is present. Testing for CRP isn’t a long or complicated process. The patient is asked for a blood sample; the sample is processed in a lab, where the protein counts and cell behaviors are analyzed. The doctor will usually have the test results in just a few days. Because a CRP test is a general indicator and can give similar results for several types of disease, it is used in combination with other blood tests to give an overall picture of the patient’s health.
Lastly, it is common for people to take NSAIDs (non-steroidal anti-inflammatory drugs) such as ibuprofen and Tylenol for the muscle and joint pain symptoms of lupus; CRP levels are affected by these medications. It is important that the patient give a full medical history, including the names of any current medications, to the doctor before donating a sample of blood for testing.
