Coagulation Disorders in Patients with Monoclonal Gammopathies

The relationship between monoclonal gammopathy of undetermined significance and venous thromboembolic disease

INTRODUCTION

Monoclonal gammopathy of undetermined significance (MGUS) has been proposed to be a risk factor for venous thromboembolic disease (VTE). However, no series published to date has been population-based or included a control group with similar comorbidities to people with MGUS.

PATIENTS/METHODS

We reviewed the records of all the male veterans in a single VA healthcare system with MGUS between January 1, 1996 and December 31, 2005. We compared the rate of VTE in 166 patients with MGUS with the rate of VTE in an age-matched control group of 465 patients who had tested negative for monoclonal gammopathy by serum protein electrophoresis (SPEP).

RESULTS

The VTE rate in the MGUS group was 2.2 per 100 person-years, which was not significantly different from the rate in the control group, 1.4 per 100 person-years (HR 1.38, CI 0.63-3.01, p=0.42). Most VTE events occurred within 4 months of the diagnosis of MGUS. In univariate analysis, albumin level (HR 0.21, CI 0.1-0.41, p<0.001), abnormal leukocyte count (HR 2.53, CI 1.09-5.86, p=0.03), and history of prior VTE (HR 4.41, CI 1.69-11.54, p=0.003) were associated with increased risk of VTE. On multivariate analysis, albumin level and history of prior VTE remained significant, but presence of MGUS was still not significantly associated with VTE risk.

CONCLUSION

Our results suggest that the increased rate of VTE in people with MGUS may be primarily due to other underlying conditions that led to testing for a monoclonal gammopathy rather than to the monoclonal gammopathy itself.

Fibrinolytic activity in multiple myeloma

The incidence of thromboembolic events is high as a result of disease, disease-related complications, and therapy in multiple myeloma (MM). In patients with hematologic tumors, impaired fibrinolysis may be present and may contribute to the development of thrombotic complications. Therefore, we designed a study to investigate fibrinolytic activity in MM. We compared plasma levels of interleukin (IL)-6, C-reactive protein (CRP), IL-1beta, IL-11, tissue plasminogen activator (tPA) activity, plasminogen activator inhibitor-1 (PAI-1) activity, and global fibrinolytic capacity (GFC) in patients with MM (n = 66) and in control subjects (n = 18). The prevalence of venous thromboembolism was 4.5%, with a median follow-up period of 7 months in our myeloma group. Results are given as mean (median, range). Plasma levels of IL-6 (8.27 +/- 0.74 [9.65, 0.90-13.32] pg/mL versus 2.64 +/- 0.66 [1.80, 0.10-11.86] pg/mL, P < 0.001), CRP (45.57 +/- 9.92 [21.00, 1.34-330.00] mg/L versus 1.96 +/- 0.50 [1.05, 0.19-8.03] mg/L, P < 0.001), PAI-1 (7.40 +/- 0.67 [5.57, 2.40-31.80] IU/mL versus 4.73 +/- 0.65 [3.60, 2.32-11.00] IU/mL, P < 0.01), GFC score (1.90 +/- 0.02 [2, 1-3] versus 2.50 +/- 0.14 [3, 1-3], P < 0.001) were increased compared with controls. In patients with MM, the level of IL-6 was positively correlated with CRP (r = 0.66, P < 0.001), IL-1beta (r = 0.29, P < 0.05), and PAI-1 (r = 0.35, P < 0.01) and negatively correlated with GFC (r = -0.37, P < 0.01). CRP level was positively correlated with plasma PAI-1 level (r = 0.40, P < 0.01) and negatively correlated with GFC (r = -0.44, P < 0.001). A significant negative correlation between PAI-1 level and GFC (r = -0.75, P < 0.001) was also detected. IL-1beta levels were negatively correlated with tPA level (r = -0.26, P < 0.05). These results suggest that patients with myeloma have a decreased fibrinolytic activity mainly because of increased PAI-1 activity. In MM, increased PAI-1 activity seems to be related with elevated IL-6 level. MM should be considered as a hypercoagulable state as a result of both increased procoagulant activity and decreased fibrinolytic activity. Achieving a plateau by means of conventional chemotherapies does not improve the decreased fibrinolytic activity.

Monoclonal gammopathies of undetermined significance: a review

Monoclonal gammopathy of undetermined significance (MGUS) denotes the presence of a monoclonal protein (M-protein) in patients without evidence of multiple myeloma (MM), macroglobulinemia, amyloidosis (AL), or a related plasma cell proliferative disorder. MGUS is found in approximately 3% of persons older than 70 years and in about 1% of those older than 50 years. In a series of 1384 patients from south-eastern Minnesota in whom MGUS was diagnosed at Mayo Clinic from 1960 through 1994, the risk of progression was 1% per year. Patients were at risk of progression even after 25 years or more of a stable monoclonal gammopathy. The risk of development of MM was increased by 25-fold, the risk of macroglobulinemia was 46-fold, and the risk of primary AL was 8.4-fold when compared with a similar population (Surveillance, Epidemiology and End Results). The concentration of the serum M-protein was the major independent predictor of progression. Patients with an immunoglobulin M (IgM) or an IgA monoclonal gammopathy had a higher risk of progression than those with an IgG monoclonal gammopathy. The presence of a urine M-protein or the reduction of one or more uninvolved Igs was not a risk factor for progression. MGUS may be associated with many different disorders, including lymphoproliferative diseases, leukemia, connective tissue disorders, dermatologic diseases, and neurologic disorders.

Monoclonal gammopathy of undetermined significance (MGUS)

MGUS is characterized by a serum M-protein concentration of less than 30 milligrams (3 g/dl), fewer than 10% plasma cells in the bone marrow, no or only small amounts of M-protein (Bence Jones protein) in the urine, the absence of lytic lesions, anaemia, hypercalcaemia and renal insufficiency, and most importantly, stability of the M-protein and failure of the development of additional abnormalities. Electrophoresis on agarose, followed by immunoelectrophoresis or immunofixation for the identification of the type of M-protein, is recommended. In 1994, 971 patients at the Mayo Clinic were found with a serum M-protein. The most frequent diagnosis was MGUS, which occurred in 52% of patients. MGUS is found in approximately 3% of people older than 70 years and in at least 1% of those aged over 50. The incidence of monoclonal gammopathies increases with advancing age and is higher in African-Americans than in Caucasians. Two hundred and forty-one patients from the Mayo Clinic with a monoclonal gammopathy but no evidence of MM, macroglobulinaemia, amyloidosis, lymphoma or related disorders were followed for 24-38 years. In 62 patients (26%), multiple myeloma, macroglobulinaemia, amyloidosis or a malignant lymphoproliferative disorder developed (the actuarial rate of development of serious disease at 10 years was 16%; at 20 years, 33%; and at 25 years, 40%). Thirty patients (12%) were alive and had a stable M-protein value. In 23 patients (10%), the serum M-protein level increased to 30 milligrams (3 g/dl) or more, but they did not require therapy for myeloma or related disorders. Fifty-two per cent of patients (126) died of unrelated diseases without the development of a malignant plasma cell lymphoproliferative disorder. The actual rate of development of serious disease was the same for those with IgG, IgA and IgM M-proteins. Differentiation of MGUS from myeloma or macroglobulinaemia is difficult. The M-protein value must be measured periodically and clinical evaluation carried out to determine whether or not serious disease has developed.