RENAL STATUS OF MULTIPLE MYELOMA PATIENTS IN IBADAN, NIGERIA

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F.A Fasola¹, K.I.I Eteng¹, W.A Shokunbi¹, J.O Akinyemi² and B.L Salako³

1. Departments of Haematology, University College Hospital, Ibadan.
2. Departments of Epidemiology and Medical Statistics, University College Hospital, Ibadan.
3. Departments of Medicine, University College Hospital, Ibadan.

Abstract

Introduction: The spectrum of clinical manifestation in multiple myeloma (MM) ranges from asymptomatic disease to severely debilitative state. Unexplained renal disease is an indication for the investigation of patients for MM. This study is a retrospective analysis of the renal profile of patients with multiple myeloma in relation to management strategy in our institution.

Methods: Medical records of 64 patients with multiple myeloma seen between 2000 and 2008 were retrospectively reviewed at an 850–bed tertiary hospital in South-Western Nigeria. The Mahn- Whitney test was used to compare laboratory features between patient with renal failure and those without renal failure. Subjects with serum creatinine >2mg/dL were regarded to have renal failure. Overall survival was calculated from diagnosis to death or lost to follow-up

Results: A total of forty three patients were eligible. The renal status was categorized into three according to serum creatinine level; those with normal serum creatinine level (0.5-1.5mg/dl) were 26 (60.5%), serum creatinine level (>1.6-1.9mg/dl), and creatinine level >2mg/ dl were 3(7%) and 14(32.5%) respectively. Hyperuricaemia was observed in 6(42.9%) of MM patients with renal failure compared with 7(26.9%) of patient without renal failure (p<0.05). Twenty– one percent of those with renal failure had hypercalceamia. Thirty– six percent of the renal failure patients had haemodialysis. The average survival for all patients with renal failure was 18 months after diagnosis.

Conclusion: The outcome in patients with renal failure remained poor with early mortality despite supportive management. Hyperuricaemia and dehydration, given the hot climate might have worked in concert with other factors to worsen the renal status in these patients.

Keywords: renal, creatinine, myeloma, dehydration

Introduction

Multiple Myeloma (MM) is a malignant clonal proliferation of plasma cells, which are terminally differentiated B–cell. It is invariably accompanied by production of monoclonal (M) protein. The diagnosis is hinged on bone marrow plasmacytosis >10% or histological confirmation of plasmacytoma, a monoclonal protein in the serum and/or urine (except in non-secretory myeloma) and bone disease. Spectrum of clinical manifestation ranges from asymptomatic disease to severely debilitative state. The tumor, its product and the host response to it result in a number of clinical features including organ dysfunction. Clinical features are heterogeneous and include renal failure, increased susceptibility to infection, anaemia, hypercalcaemia, occasionally neurological symptoms, vascular manifestation of hyperviscosity and clotting abnormality. The incidence of myeloma increases with advancing age. It is commonest among blacks¹, it accounts for 0.5% of all malignancies and 5.7% of haematological disorders in our hospital².

Kidney involvement is seen in up to 50% of cases³, and can be identified at presentation or during the course of the disease. Unexplained renal disease is an indication for the investigation of multiple myeloma. The pathology is heterogeneous with a variety of pathogenetic mechanisms³, many factors contribute to this renal lesion, most frequent being deposition of monoclonal immunoglobulins or fragments with cast nephropathy^3,4. Tubular damage associated with the excretion of light chains is almost always present⁴. Renal status of MM patients is an important prognostic determinant, and this forms the basis for subdivision of Durie-Salmon staging into A and B. Thus the approach to management is often modified by the patient’s renal status.

This aim of this study was to assess the renal profile of patients with multiple myeloma in relation to current management strategies in our institution.

MATERIALS AND METHOD
Medical records were retrospectively reviewed for all patients diagnosed as multiple myeloma in the Haematology department of a tertiary hospital in South-Western Nigeria between 2000 and 2008. Multiple myeloma was defined by at least 2 of the following-bone marrow with clonal plasma cells of at least 10% or histologic confirmation of a plasmacytoma; a monoclonal protein in the serum or urine (unless the patient has a nonsecretory myeloma); and end-organdamage evidenced by renal insufficiency, hypercalcemia, anemia, or lytic bone lesions (International Myeloma Working Group, 2003, Rajkumar & Kyle, 2005).

Forty three patients who met the diagnostic criteria and had complete data with regard to availability of serum creatinine, urea and electrolytes were included in the study. The presenting features and significant co-morbidity were recorded. All patients included in this study had bone marrow plasmacytosis greater than 30%. Clinical staging was determined according to the Durie -Salmon system. Drug regimen, supportive care and outcome were recorded.

Renal status was categorized into normal, renal insufficiency and renal failure using results of seru creatinine. Normal renal status was defined by the hospital laboratory reference value of serum creatinine level between 0.5 and 1.5mg/dl. Renal insufficiency was defined as a serum creatinine level of 1.6–1.9 mg/ dl while renal failure was defined as serum creatinine >2 mg/dl. In all the patients, diagnosis of renal disease was made at the time of investigating patient for MM. In line with the International Prognostic Index (IPI) hypoalbuminaemia was defined as serum albumin <3.5mg/l

A corrected calcium concentration = Serum calcium concentration + 0.02 (40 – serum albumin concentration) was calculated for each patient.

Statistical Analysis
The Kruskal Walliis test was used to compare the biochemical parameters of MM patients with renal failure and those without. The survival time was calculated as number of months from diagnosis to death or date of last follow-up. Survival rates were estimated using the Kaplan – Meier method while the long rank test was used to compare the survival rate between the two categories of MM patients (with and without renal failure). P-values less than 0.05 were considered statistically significant.