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276 / Chapter 21 Multiple myeloma and related disorders

4 Features of renal failure and/or hypercalcaemia: have IgD or IgE paraprotein and a similar
polydipsia, polyuria, anorexia, vomiting, consti- number are non - secretory.
pation and mental disturbance. 2 Elevated serum immunoglobulin - free light
5 Abnormal bleeding tendency: myeloma protein chains Immunoglobulin - free light chains
may interfere with platelet function and coagula- (FLC) are κ or λ light chain proteins, synthesized
tion factors; thrombocytopenia occurs in by plasma cells that have not been paired with

advanced disease. heavy chain (Fig. 21.4 ). They are normally made

6 Amyloidosis occurs in 5% with features such as in small quantities and filtered from the serum

macroglossia, carpal tunnel syndrome and into the kidney but can be measured in serum.
diarrhoea. Free light chains are produced by almost all
7 In approximately 2% of cases there is a malignant plasma cells and so the serum free light
hyperviscosity syndrome with purpura, haemor- chain assay is useful in diagnosis and monitoring
rhages, visual failure, central nervous system of myeloma and other forms of malignant para-
(CNS) symptoms, neuropathies and heart proteinaemia. Typically in myeloma there is an
failure. increase in either the κ or λ serum free light
chain value. The normal κ : λ serum free light

Laboratory findings include the following:
chain ratio of 0.6 (range 0.26 – 1.65) is also
1 Presence of a paraprotein Serum and urine skewed with an excess of either κ or λ chains.

should be screened by immunoglobulin electro- Light chain assays have largely replaced the need

phoresis. The paraprotein is immunoglobulin G for analysis of urine paraproteinaemia.
(IgG) in 60% of cases, IgA in 20% and light 3 Normal serum immunoglobulin levels (IgG,
chain only in almost all the rest. Less than 1% IgA and IgM) are reduced, a feature known as

(a)

Figure 21.4 The value of serum

immunoglobulin - free light chain (FLC)
measurement in multiple myeloma.
(a) Serum free light chains are
immunoglobulin light chains that are
synthesized by plasma cells but not paired
with heavy chains before they are released
(b) into the blood. Low levels are found in
10 5 4 normal individuals and these are increased
Serum lambda FLC (mg/L) 10 10 3 2 Normal sera patients with renal impairment and those
in patients with myeloma. (b) Profi le of
10
serum free light chains in healthy controls,
Kappa LCMM
with κ or λ light chain multiple myeloma
10
Lambda LCMM
(LCMM). As light chains are normally
Renal impairment
fi ltered by the kidney, their levels rise in

the κ : λ ratio remains normal. (From

0.1 1 patients with renal impairment although
0.1 1 10 10 2 10 3 10 4 10 5 Hutchison C. (2008) BMC Nephrology 9 ,
Serum kappa FLC (mg/L) 11 – 19; Bradwell A.R. (2003) Lancet 361 ,
489 – 91.)