Clinical Biochemistry 43 (2010) 534–536
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Clinical Biochemistry j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / c l i n b i o c h e m
Case Report
Bisalbuminuria detected by agarose gel electrophoresis Ahmad Al-Sarraf a,⁎, Chiman Chow b, Arun Garg b a b
University of British Columbia Department of Pathology and Laboratory Medicine, Vancouver, BC, Canada Department of Laboratory Medicine and Pathology, Royal Columbian Hospital, Vancouver, BC, Canada
a r t i c l e
i n f o
Article history: Received 10 November 2009 Accepted 6 December 2009 Available online 21 December 2009 Keywords: Bisalbuminuria Agarose gel electrophoresis Bisalbuminemia Capillary electrophoresis Electrophoresis using cellulose acetate
Bisalbuminuria is a rare condition characterized by the presence of two distinct fractions of urinary albumin on electrophoresis. While many cases of bisalbuminemia have been reported there are only a few reports of bisalbuminuria [1–3]. Urinary albumin can dimerize when it is stored at − 14 °C in urine with high protein content or if the patient is on steroids [4]. We report the presence of a dimerized albumin in freshly voided urine from a patient who was not taking steroid or any other drug known to be associated with the presence of a dimerized albumin. The patient was an 82–year-old Canadian aboriginal woman who presented with multiple problems that included ischemic heart disease, type 2 diabetes, chronic renal failure, hyperlipidemia, hypothyroidism, hypertension and chronic obstructive pulmonary disease. She was taking levothyroxine, temazepam, lisinopril, amlodipine, plavix, metoprolol, lasix, insulin and ventolin. She was admitted for hip fracture, underwent surgery and was discharged from hospital after a few weeks in a stable condition. Results In hospital, investigations showed hemoglobin 90 g/L, leukocyte count 8.8 × 109/L with 60% neutrophils. Serum creatinine was 162 μmol/L and eGFR 26 mL/min/1.73 m2 BSA. Qualitative urine examination was negative for proteinuria. Given the history of anemia and hip fracture, serum protein electrophoresis was performed to rule out multiple myeloma. This test revealed a single albumin fraction and no monoclonal peaks in the gamma globulin region (Fig. 1). Quantitative urine examination showed 0.45 gram protein. Urinary ⁎ Corresponding author. 2502-928 Beatty Street, Vancouver, BC, Canada V6Z366. E-mail address:
[email protected] (A. Al-Sarraf).
electrophoresis revealed two unequal albumin bands (Fig. 2). The mobility of the albumin variant relative to the normal albumin was determined by comparison with the normal albumin peak in the instrument database and by electrophoresis of a different patient urine sample. The fraction of albumin was 64% of total urine protein. The globulin fraction was 0.14 g (alpha one globulin 0.02, beta globulin 0.05 and gamma globulin 0.07). On immunofixation there was a single albumin fraction in the serum (Fig. 3) but urine showed presence of two albumin components (Fig. 4). Method Total protein measurement was measured via the biuret method. The biuret method operates on the principle that amino acid chains (containing 2 or more peptide bonds) will form a blue complex with cupric salts in basic conditions. Serum albumin, a negatively charged protein that binds to anionic dyes, was measured by the bromocresol purple dye method. Urine and serum proteins were electrophoresed on agarose gel using SEBIA hydragel HR/ Hydrasys. Hydragel uses a support gel of agarose which has pH of 8.6, at which all proteins form anions. When an electrical current is applied to the electrodes at either end of the gel the proteins travel to the anode according to their charge to mass ratio, allowing the proteins to be separated into distinct zones. The relative amounts of urinary albumin were quantified by densitometry. Serum and urine proteins were separated by immunofixation on agarose gel using SEBIA Hydrogel 4 IF acid violet. Discussion In this case, bisalbuminuria was identified using agarose gel as opposed to capillary electrophoresis or electrophoresis using cellulose
0009-9120/$ – see front matter © 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.clinbiochem.2009.12.006
A. Al-Sarraf et al. / Clinical Biochemistry 43 (2010) 534–536
Fig. 1. Serum protein electrophoresis on agarose gel reveals single albumin fraction in patient.
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Fig. 3. Serum protein immunofixation on agarose gel indicates single albumin fraction.
acetate [3,5,6]. In previous studies, it had been reported that capillary electrophoresis had an advantage over agarose gel electrophoresis for albumin separation [5,6]. While capillary electrophoresis may identify more cases of bisalbuminuria, in this study, agarose gel electrophoresis was successful in identifying the condition.
Several authors reported that North American Indian populations have a relatively high frequency of bisalbuminemia [1]. This patient's bisalbuminuria may be related to her ethnicity; however, family members were not available and, as such, we could not investigate this hypothesis further. Beilby et al. [3] described a case of bisalbuminuria in an Australian aboriginal with chronic renal failure. We speculate that renal failure may be a contributing cause of the bisalbuminuria in our patient. Medications are another possible reason for this patient's results given that steroids are a reported cause of bisalbuminemia. Acquired bisalbuminemia (which potentially results in bisalbuminuria) could be indicative of overdose of antibiotics, or of the presence of a pancreatic cyst or pseudocyst [7,8].
Fig. 2. Urine protein electrophoresis on agarose gel reveals two distinct fractions of albumin in affected member patient (lane 7).
Fig. 4. Urine protein immunofixation on agarose gel reveals two distinct fractions of albumin.
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