Amyloidosis

Question 1

what is it?

Answer 1

deposition of extracellular amyloid (insoluble protein fibrils) in tissues/ organs
abnormal folding of proteins - aggregate - insoluble: breakdown of usual degradation pathways for abnormally folded proteins
>30 identified proteins
inherited/acquired
UK wide - approx 800 new cases

Question 2

what are the different types of amyloidosis?

Answer 2

primary/ light chain (AL)
secondary/ systemic/ inflammatory (AA)
dialysis (AB2M)
hereditary and old age (ATTR)

Question 3

AL amyloidosis

Answer 3

abnormal immunoglobulin light chain from plasma cells
light chains enter bloodstream - amyloid deposits
3-13 / million/ year
common sites: bowel, skin , nerves, kidney
age: 55-60
life expectancy 6 months - 4 yrs (untreated)

Question 4

AA amyloidosis

Answer 4

is associated with systemic inflammation
production acute phase protein - serum amyloid protein (SAA)
in 5% of patients with chronic inflammatory conditions/chronic infections
- RA, IBD, psoriasis
- TB, osteomyelitis, bornchoiectasis
2/ million/ year
common sites: liver, spleen, kidneys, adrenals

Question 5

how does it present?

Answer 5

depends on organs/ tissues involved
renal (nephrotic range) proteinruria +/- impaired renal function
cardiac - cardiomyopathy
nerves - peripheral/ autonomic neuropathy
hepatomegaly/splenomegaly
GI - malabsorption

Question 6

how is it investigated?

Answer 6

urinalysis + uPCR
blood test - renal function markers of inflammation, SFLC
renal biopsy - congo red staining - apple green under polarised light
other biopsy - abdominal fat pad/ rectal biopsy
SAP scan - scintigraphy with radiolabelled serum amyloid

Question 7

how is it managed?

Answer 7

not curative
aim - reduce further deposition
AA - treat underlying condition
AL - immunosuppression - steroids, chemo, stem cell transplant