Myeloma & Paraproteins Flashcards
Describe the basic structure of an antibody?
Y shaped with 2 heavy and 2 light chains
“Trunk” = FC portion (constant & defines subclass)
“Branches” = FAB portion (variable & defines antigen binding)
What’s the most common antibody?
IgG - 75% of total
So the heavy chain determines an immunoglobulins subclass. What does the light chain do?
Each cell randomly selects if it will have Kappa or Lambda light chains
Some free light chains can be tested for in the blood to indicate which is more common
What is a paraprotein?
A monoclonal Ab in blood or urine (i.e. lots of the same Ab) indicating monoclonal proliferation of a B-cell type
How can we test antibody levels?
Total Immunoglobulin levels
How do we assess for antibody diversity & paraproteins?
Serum Protein Electrophoresis
Seperates the proteins incl antibodies by size/charge
How do we determine which class of paraprotein is present?
Immunofixation
Light chains aren’t detected in electrophoresis but can cause myeloma, how do we test for them?
Light Chain Assay
What if we find a paraprotein in someone with no illness?
Diagnose with MGUS
Monoclonal Gammopathy of Uncertain Significance
How do we diagnose a myeloma?
Usually indicated by a paraprotein
Then we must find Excess Plasma Cells in the marrow (>10% of total marrow cell pop)
How do we stage myeloma?
BAsed on Albumin & Beta2 Microglobulin levels
What is a myeloma?
A neoplasm of plasma cells –> Excessive production of a single immunoglobulin
Who gets myeloma?
Peaks in the 7th decade
And is commonest amongst black people
Presentations of myeloma can occur through Plasma cells or the paraprotein. what could the plasma cells cause?
- Bone disease (Lytic lesions, path fractures, cord compression & hypercalcaemia)
- Marrow failure (esp anaemia)
- Infections
What presentations of myeloma can be caused by the paraprotein?
Renal failure (Cast Nephropathy)
Hyperviscosity Syndrome –> Bleeding e.g. retinal, oral, nasal or cutaneous. Sometimes HF, confusion or renal failure
Hypogammaglobulinaemia –> Infections
Amyloidosis
How can we treat Myeloma?
Chemo RT Bisphosphonate Steroids Surgery Autologous Stem Cell Transplant
Why use bisphosphonates in myeloma?
Treat the bone disease, very like osteoporosis
What is surgery used for in myeloma?
Pinning long bones and decompressing the spinal cord
How does an autologous stem cell transplant work?
ITs not the transplant that treats you, its the chemo:
1) Shrink myeloma as much as possible
2) Harvest healthy stem cells
3) Hardcore chemo destroys myeloma & normal marrow
4) Stem cell transplant (prevents you dying from the marrow damage of chemo)
Which immunoglobulins are present in myeloma?
IgA & IgG
IgM paraproteins can be found instead in lymphoma
So what is the most common presentation of myeloma?
Bone pain & anaemia
Sometimes with infection, fatigue or renal impairment
What tests can you do in myeloma?
Serum protein electrophoresis to identify presence of a paraprotein
Bone marrow aspirate/biopsy (>10% B cells)
Serum Ca, FBC, skeletal survey & U&Es + creatinine are all to assess complications
Albumin & B2 Microglobulins for Staging
