Abstract: SA-PO224
A Case of Monoclonal Gammopathy Presenting with an Unexpectedly High Level of Serum Creatinine Due to Positive Interference in an Enzymatic Assay
Session Information
- Trainee Case Reports - V
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Reports
- 1502 Pathology and Lab Medicine: Clinical
Authors
- Mizuhara, Ryoko, Tokai University School of Medicine, Isehara, kanagawa, Japan
- Hamano, Naoto, Tokai University School of Medicine, Isehara, kanagawa, Japan
- Koizumi, Masahiro, Tokai University School of Medicine, Isehara, kanagawa, Japan
Group or Team Name
- Tokai University School of Medicine Division of Nephrology, Endocrinology, and Metabolism
Introduction
In Japan, serum creatinine level is routinely measured by enzymatic method and a variety of enzyme assay kits are available. Monoclonal gammopathy can interfere with enzymatic assay for creatinine.
Case Description
A 78-year-old man was referred to the department of thoracic surgery in our hospital for the evaluation of lung tumor. At the initial visit to our hospital, the level of serum creatinine increased sharply from 1.03 mg/dl to 4.68 mg/dl during 5 days before the referral. He was generally well, and did not complain of anorexia, fever or oliguria. (No causative drug or infection was detected.) Other laboratory tests revealed a BUN level of 21 mg/dL, almost normal urinalysis (with microscopic hematuria), and an IgM level of 1366 mg/dL. We performed kidney biopsy, but could not identify the cause of AKI. In the meantime, we diagnosed lymphoplasmacytic lymphoma based on bone marrow biopsy. Despite high creatinine level measured in our hospital, that measured in the other hospital soon after the biopsy was nearly normal. To elucidate the cause of the discrepancy in the measured values, we analyzed the measurement methods.
We observed the formation of white precipitation after addition of the reagent of the creatinine assay kit using in our hospital to the serum of this patient. This turbidity was not found when measuring by Jaffe method or by enzymatic method after protein removal from his sera, leading to the diagnosis of pseudohypercreatininemia secondary to paraproteinemia. GFR estimated from serum cystatin C was 33.3 ml/min/1.73m2, consistent with that from ”true” serum creatinine.
Discussion
Pseudohypercreatininemia should be considered in the search for the cause of isolated creatinine elevation in patients with paraproteinemia. In such patients, we should measure serum creatinine by multiple methods to evaluate renal function accurately. Comprehensive evaluation of creatinine measured by multiple methods and cystatin C may provide accurate renal function of patients with monoclonal gammopathy.