Monoclonal Gammopathy of Undetermined Significance

Question 1

MGUS

Answer 1

Monoclonal gammopathy of undetermined significance (MGUS, also known as benign paraproteinaemia and monoclonal gammopathy) is a common condition that causes a paraproteinaemia and is often mistaken for myeloma.

Around 10% of patients eventually develop myeloma at 5 years, with 50% at 15 years

Features
usually asymptomatic
no bone pain or increased risk of infections
around 10-30% of patients have a demyelinating neuropathy

Question 2

Differentiating Features from Myeloma

Answer 2

Differentiating features from myeloma
normal immune function
normal beta-2 microglobulin levels
lower level of paraproteinaemia than myeloma (e.g. < 30g/l IgG, or < 20g/l IgA)
stable level of paraproteinaemia
no clinical features of myeloma (e.g. lytic lesions on x-rays or renal disease)

ABSENCE OF Cx inc:

• immune paresis (?)
• hypercalcaemia
• bone pain

Question 3

MGUS - Diagnosis

Answer 3

The diagnosis of MGUS can be made in patients who fulfil the following criteria -
A monoclonal paraprotein band lesser than 30 g/L (< 3g/dL)
Plasma cells less than 10% on bone marrow examination
No evidence of bone lesions,anemia, hypercalcemia, or renal insufficiency related to the paraprotein
No evidence of another B-cell proliferative disorder

Question 4

MGUS - Example Question

Answer 4

A 62 year old man is attending his GP as part of regular screening. He has a past medical history significant only for hypertension for which he has been taking amlodipine for many years. He reports no specific symptoms of note and is still working full time as an accountant. His blood pressure on this visit is 132/78mmHg and his urinalysis shows no abnormalities. Blood tests were taken for routine monitoring.

Hb 13.8 g/dl
Platelets 362 * 109/l
WBC 6.3 * 109/l

Na+ 142 mmol/l
K+ 4.2 mmol/l
Urea 4.6 mmol/l
Creatinine 84 µmol/l

Adjusted calcium 2.41mmol/l
Lactate Dehydrogenase 300 IU/l
Albumin 36 g/l
Globulin 52 g/l

An abnormal protein band is detected during analysis and the GP arranges for further review with the Haematologist at the hospital. Further investigations are undertaken:

Monoclonal paraprotein 18g/l
Bone Marrow examination showing 6% plasma cells
Skeletal Survey showing no abnormalities

What is the diagnosis?

Multiple Myeloma
Hodgkins Lymphoma
Waldenström's macroglobulinemia (lymphoplasmacytic lymphoma)
Asymptomatic Myleoma
> Monoclonal gammopathy on uncertain significance (MGUS)

Monoclonal gammopathy on uncertain significance (MGUS) is a condition where an abnormal paraprotein is found in the blood, often during routine testing. It is on a spectrum that includes multiple myeloma but at the MGUS stage no treatment is indicated. The level of serum paraprotein is lower than in myeloma (under 30g/l) and the number of plasma cells in the bone marrow is also lower (less than 10%). The condition is totally asymptomatic. There is an annual risk of progression to myeloma of 1-2% and as such annual surveillance is recommended.

Question 5

MGUS

Answer 5

Monoclonal gammopathy on uncertain significance (MGUS) is a condition where an abnormal paraprotein is found in the blood, often during routine testing. It is on a spectrum that includes multiple myeloma but at the MGUS stage no treatment is indicated. The level of serum paraprotein is lower than in myeloma (under 30g/l) and the number of plasma cells in the bone marrow is also lower (less than 10%). The condition is totally asymptomatic. There is an annual risk of progression to myeloma of 1-2% and as such annual surveillance is recommended.