Baylor University Medical Center Proceedings January 2014, Volume 27, Number 1 | Page 22

Table 1. Timeline of therapy and corresponding pertinent laboratory values
Free kappa
(mg/L)

Free lambda
(mg/L)

Kappa/lambda
ratio

M-band
(g/dL)

Urine protein
(mg/24 h)

On presentation (11/22/2011)

86.6

14.2

6.1

1.5

4340

On prednisone (2/21/2012)

16.6

7.9

2.1

0.3

4800

After cyclophosphamide and prednisone (8/8/2012)

29.7

7.7

3.9

0.6

2027

On prednisone (2/24/2013)

67.6

7.2

9.3

1

3456

On maintenance cyclophosphamide and dexamethasone
(3/24/2013)

54.1

9.3

5.8

1.1

Time

a calcium level of 9.1 mg/dL and a hemoglobin of 14.9 g/dL.
His skeletal survey did not show any lytic lesions. A magnetic
resonance imaging skeletogram was also negative.
The patient was started on oral prednisone 1 mg/kg in
addition to his angiotensin receptor blocker and angiotensinconverting enzyme inhibitor. Three months later, his proteinuria
had not decreased, whereas there was a reduction in his free
light chains and a monoclonal protein spike. Since the patient
was still having severe proteinuria, cyclophosphamide (1 g intravenously every month) was started, and the prednisone was
tapered to 5 mg/day. After 6 months of treatment with cyclophosphamide and low-dose prednisone, the patient’s proteinuria
and serum monoclonal protein were lower. Cyclophosphamide
was stopped and the low-dose prednisone continued. His serum free kappa light chain as well as his 24-hour proteinuria
increased within a matter of weeks (Table 1). At that time dexamethasone (20 mg by mouth weekly) and cyclophosphamide
(1 g every 8 weeks) were begun, and both the free light chains
and proteinuria responded to this treatment.
DISCUSSION
In most patients with plasma cell disorder, the renal lesion
is paraprotein related (1). The most common paraproteinassociated lesions are myeloma cast nephropathy, monoclonal immunoglobulin deposition disease, and amyloidosis. In
such cases the treatment for the renal lesion is to treat the
underlying cause, i.e., myeloma. The most common non–
paraprotein-associated lesions seen on renal biopsy are acute
tubular necrosis, hypertensive arteriosclerosis, and diabetic
nephropathy (1). These have been attributed to a variety of
causes: hypercalcemia, drug toxicity (e.g., nonsteroidal antiinflammatory drugs), contrast exposure, and other coexisting
illnesses such as diabetes mellitus and hypertension. The wellestablished connection of FSGS with myeloma is pamidronate;
it is used to treat hypercalcemia due to bone lesions, including
lytic lesions as seen in myeloma. Exposure to pamidronate has
been described to cause a characteristic collapsing variety of
FSGS (2). The absence of any myeloma-related renal pathology, the presence of glomerulosclerosis, and a negative etiological workup for proteinuria pointed towards an idiopathic
FSGS in our patient. However, some may still argue that the
two processes are in fact related (3).
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It has been reported that patients with smoldering multiple
myeloma (SMM) will progress to symptomatic myeloma or
amyloidosis at an approximate rate of 10% per year for the first
5 years, 3% per year for the next 5 years, and 1% to 2% per
year for the following 10 years (4). Risk factors for progression
include a high serum monoclonal protein level, a high proportion of plasma cells in the bone marrow, and a high serum
free light chain ratio (5). Currently, H