Amyloid proteins can build up for a long time before causing any symptoms, so the disease usually is not diagnosed until it is well established. Because the symptoms associated with amyloidosis are common to several different diseases, your doctor may run many different tests to check for other diseases first.
He or she will begin with a general examination to look for signs of disease that might be caused by amyloidosis. The examination might include:
Examining joints for signs of joint swelling
Examining the skin for rashes or discoloration
A test checking for blood in the stool or an endoscopic procedure (in which a flexible, lighted tube with a tiny camera on the end is inserted into the rectum to the colon, or into the stomach through the mouth) to detect gastrointestinal bleeding
Testing the heart for evidence of heart failure or enlargement
Testing muscles for signs of weakness
Examining hands, feet, arms and legs for signs of fluid swelling or poor sensation
Checking mental status to assess possible dementia
Urine will be collected to test for excess protein, which is often a first sign of systemic amyloidosis that has infiltrated the whole body. Blood will be drawn and tested to look for evidence of abnormal blood counts, kidney or liver disease, or abnormal protein.
The only definitive test for amyloidosis is a biopsy, in which a small sample of affected tissue is removed surgically and examined. The amyloid protein can be identified when the biopsy specimen is stained and viewed under a microscope. Increasingly, DNA and protein analysis are used to identify different types of amyloidosis.
When the entire body is affected (a condition called systemic amyloidosis), biopsies of the rectum or from abdominal fat often reveal the diagnosis. If the amyloid has accumulated in a single organ, such as the brain, the biopsy needs to come directly from that organ. For this reason, many types of amyloidosis are difficult to diagnose. For example, in Alzheimer's disease, a biopsy of brain tissue rarely is done. The biopsy could injure the brain and while the results might provide a diagnosis, it would be unlikely to change treatment (because there is no effective treatment for amyloid in the brain). When amyloidosis is diagnosed or highly suspected, additional blood and urine tests will be done to look for diseases that could cause the protein accumulation.