What Is Renal Amyloidosis, and How Is It Detected?

Amyloidosis is not a single disease, but a group of medical conditions caused by proteins that fold abnormally, known as “amyloid proteins.” This abnormal folding creates small fibers or “fibrils” that the body cannot break down, and which can accumulate in different organs. Over time this accumulation can cause damage or failure of the organ. When this happens in the kidneys, it is known as “renal amyloidosis.”

There are approximately 30 different forms of amyloidosis in humans, each involving different amyloid proteins, which may deposit in one organ or several different organs. Amyloid accumulation in the kidney is more likely to result in symptoms than some other organs, and for this reason, this is often where amyloidosis is first detected.

Different types of amyloidosis are named according to the type of amyloid protein which is produced. All begin with the initial ‘A’ which stands for amyloidosis. The ‘A’ is followed by one or more other letters, which identify the particular amyloid protein. For example: AL amyloidosis, ATTR amyloidosis, and ALECT2 amyloidosis (see table below for more details).

Learn more about the REFLECTION natural history study of individuals with ALECT2

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Symptoms and diagnosis of renal amyloidosis

There are many signs and symptoms that can indicate amyloidosis in the kidneys. Individuals may have different symptoms depending on the type of renal amyloidosis they have, and how far the damage to the kidneys has progressed.

These can include:

  • General symptoms of fatigue, shortness or breath, low blood pressure, and weight loss
  • Signs from blood and urine tests that indicate the kidney is not removing waste products from blood properly – called ‘renal insufficiency’
  • A group of symptoms that signal kidney damage called “nephrotic syndrome,” which include the following
    • Increased levels of albumin or protein in the urine (called albuminuria and proteinuria)
    • Higher than normal amounts of lipids (fats, such as cholesterol) in the blood
    • Swelling of legs, feet, ankles, hands, or face (called edema)
    • Lower-than-normal amounts of albumin in the blood (called hypoalbuminemia)

Renal amyloidosis is diagnosed by a kidney biopsy. Amyloid fibrils in the kidney tissue can be seen under a microscope using a special stain called “congo red.”

Most common types of renal amyloidosis

Amyloidosis diagnosis Amyloid protein Description
AL amyloidosis Antibody light chains
  • Most common renal amyloidosis
  • Sometimes called primary amyloidosis
  • Linked to a type of blood cancer called multiple myeloma
  • Can also affect the liver, heart, digestive tract and nerves
AA amyloidosis Amyloid A protein
  • Rare complication that may happen after prolonged infection or inflammatory disease
  • Sometimes called secondary amyloidosis
  • Can sometimes also impact the heart, liver and digestive tract
ATTR amyloidosis Transthryretin
  • Full name is transthyretin (TTR) amyloidosis
  • Often inherited, as a defect in the TTR gene, but can also occur later in life without a family history
  • Often affects the heart and/or nerves more than the kidney
ALECT2 amyloidosis Leukocyte chemotactic factor 2 (LECT2)

For more information on ALECT2, visit our “About LECT2 Amyloidosis (ALECT2)” page.

Learn more about the REFLECTION natural history study of individuals with ALECT2

See if you or someone you know might be eligible for this important clinical study.