Case 197 -- Monoclonal Protein in Serum

Contributed by Michael Torbenson, MD and Robert Kelly, PhD
Published on line in May 1999


The patient is a 47 year old man working in the paint industry with a complicated past medical history that includes the following diseases:

  1. Severe diabetes, diagnosed in 1996, with peripheral neuropathy, retinopathy, end-stage renal disease, and status post right transmetatarsal amputation for osteomyelitis.
  2. Autosomal dominant polycystic kidney disease
  3. Chronic renal insufficiency
  4. Renal stones
  5. Hypertension for the past 20 years
  6. Hyperlipidemia
  7. Gout, first diagnosed five years ago

The patient was hospitalized and treated in August of 1998 for bilateral transudative pleural effusions and a pericardial effusion of unknown etiology. As part of the workup, a serum protein electrophoresis (SPEP) was performed on 9/1/98, which showed a paraprotein.

At a clinic visit on 9/14, the patient was noted to have mild hepatomegaly and possible macroglossia. A fat-pad biopsy was negative for amyloid. The patient's blood showed a normochromic normocytic anemia. A bone marrow biopsy performed that day showed normocellular marrow with trilineage hematopoiesis and 1% plasma cells. A Congo-red stain (for amyloidosis) was negative. A repeat SPEP with immunofixation demonstrated a monoclonal IgG kappa of less than 100 mg/dl. A urine protein electrophoresis was negative for light chains (Bence Jones protein).

The patient continued to have a left sided pleural effusion that waxed and waned over the next several months. A follow-up SPEP on 4/26/99 was done (Figure 1). A UPEP (Figure 2a) with immunofixation (Figure 2b) was performed on 5/6/99 .

RESULTS (Captions):

Figure 1.    SPEP shows a probable paraprotein, approximately 340 mg/dL, but insufficient serum was available to characterize the protein further.

Figure 2.   UPEP (Figure 2a) and immunofixation (Figure 2b) showed a monoclonal IgG/kappa (approximately 3.3 mg/dl) and two free lambda light chain bands, one approximately 1.9 mg/dl and one approximately 0.5 mg/dl. Note the glomerular pattern of proteinuria. The control (Figure 2a) shows a patient with a large amount of Bence Jones protein but with otherwise a relatively normal protein pattern.


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