The Rheumatoid Arthritis Factor is often evaluated in patients suspected of having any form of arthritis or destructive articular disease even though positive results can be due to other causes, and negative results do not rule out disease. But, in combination with signs and symptoms, it can play a role in both diagnosis and disease prognosis. It is part of the usual disease criteria of rheumatoid arthritis.

This lab test panel includes Total CK (or CPK) and relative percentage of BB (CK-1), MB (CK-2), and MM (CK-3); the percentage of macro CK, if present. The CK or CPK isoenzyme test is used to diagnose myocardial infarction (MI). Three fractions normally may be found, each an isoenzyme: • MM is found in normal serum. • MB is the myocardial fraction associated with MI and occurs in certain other states. MB can be used in the estimation of infarct size.

Quest Diagnostics test code 17911 is for a DNA mutation analysis of Methylenetetrahydrofolate Reductase (MTHFR). The test determines if a patient has one, two, or no copies of either of the two mutations in the MTHFR gene, C677T and A1298C.

Changes in the methylenetetrahydrofolate reductase gene can lead to certain health conditions. One of them is hyperhomocysteinemia (high blood levels of homocysteine), which is a risk factor for cerebrovascular disease, cerebral vein thrombosis, coronary artery disease, myocardial infarction, and venous thrombosis. At least 40 mutations in the MTHFR gene have been identified in people with homocystinuria, a disorder in which the body is unable to process certain amino acids properly.