Polymyositis and Liver Disease
Serum CK levels can vary according to several factors, including age, race, gender, activity level, and health status. However, elevated levels of CK in the blood often indicate muscle damage, a chronic disease, or acute injury. In addition, a higher level of CK can indicate various conditions, including myositis. However, an elevated CK level does not necessarily mean a patient has polymyositis. Further testing may be needed to diagnose the condition.
Unconjugated bilirubin
The enzymatic breakdown of heme produces bilirubin, a yellow-orange pigment found in bile. The liver's hepatocytes quickly conjugate the bilirubin with glucuronic acid. It is then rapidly transported into the bile. If the bilirubin level is high enough, the patient develops jaundice. Usually, the conjugated bilirubin level in the serum does not reach clinically detectable levels until liver failure or obstruction of the liver duct.
Patients with bilirubinemia may experience jaundice, an enlarged liver, and sclera. Yellow coloration in the tissues characterizes the disease. When the bilirubin level reaches 43 micromol/L (2.5 mg/dL), jaundice will appear in the skin and sclera. Jaundice will resolve in the reverse order of appearance. Bilirubin is a by-product of the heme metabolism process and is excreted through the biliary tract and gallbladder. Hyperbilirubinemia occurs when there is excess heme degradation or disruption of bile flow.
TIF1-g
The presence of anti-TIF1-g antibodies is associated with a rash of typical dermatomyositis. It is also associated with a reduced risk of neoplasia and arthralgia. In addition, it is the most common route of mutant allele loss in human cancers. However, anti-TIF1-g-positive patients also have widespread lesions on the skin, including poikiloderma and red-on-white telangiectatic patches.
Although there are no definitive tests for myositis, specific autoantibodies for TIF1-g may help distinguish cancer-associated myositis from other autoimmune diseases or noninflammatory myopathies. In addition to its diagnostic utility, TIF1-g has a negative predictive value of 92, which is higher than the positive predictive value of 66.7%, meaning that a negative result is a reasonable indication that there is no associated cancer.
NXP-2
Anti-NXP-2 antibodies have been associated with atypical DM in adults, but these findings are rare. Patients with anti-NXP-2 antibodies usually present with more severe muscle complaints, including dysphagia and myalgias. Therefore, the presence of anti-NXP-2 antibodies is diagnostic of DM, although other causes of polymyositis are possible.
In approximately 30% of DM patients, myositis-specific antibodies are detected. Some of these antibodies are anti-MDA-5 and anti-TIF-1, markers of myositis.
HLA-DR3
Several studies have shown an association between HLA-DR4/DR1 sequences and rheumatoid arthritis. These findings suggest that the shared epitope is involved in the etiopathogenesis of rheumatoid arthritis and may influence the disease's susceptibility, severity, and outcome.
Several other genetic factors have been implicated in the disease. For example, a person's HLA-DR3 haplotype (HLA-DR3) is a risk factor for autoimmune hepatitis, a chronic disease caused by an imbalance of immune cells in the liver. Genetic predisposition, as well as deficiencies in the complement system, can cause autoimmune hepatitis.
Dermatomyositis
People with dermatomyositis are often at a higher risk of developing cancer, which is not uncommon for those with inflammatory myopathies. In addition, the risk of developing certain types of cancer is increased with age and may also increase when patients have specific antibodies to specific cancer-causing agents. Because of these risks, people with polymyositis and dermatomyositis should be regularly screened for cancer and other diseases. This may include blood tests, chest X-rays, Pap tests, and transvaginal ultrasounds.
While symptoms may appear slowly over time, they can also occur suddenly. The condition may also wax and wane without a specific cause. If you experience any of these symptoms, you should consult a physician as soon as possible.
