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| LETTER TO THE EDITOR |
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| Year : 2012 | Volume
: 60
| Issue : 3 | Page : 242 |
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Microalbuminuria and hemoglobin risk predictors of eye diseases - Comment
S Vivekanandan
Consultant Clinical Biochemist, Dr. Vivek's Health Centre, Madipakkam, Chennai, India
| Date of Web Publication | 8-May-2012 |
Correspondence Address:
S Vivekanandan
Consultant Clinical Biochemist, Dr. Vivek's Health Centre, 6, 2nd Main Road, Sadasiva nagar, Madipakkam, Chennai-600091
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0301-4738.95888
How to cite this article:
Vivekanandan S. Microalbuminuria and hemoglobin risk predictors of eye diseases - Comment. Indian J Ophthalmol 2012;60:242 |
How to cite this URL:
Vivekanandan S. Microalbuminuria and hemoglobin risk predictors of eye diseases - Comment. Indian J Ophthalmol [serial online] 2012 [cited 2019 Dec 12];60:242. Available from: http://www.ijo.in/text.asp?2012/60/3/242/95888 |
Dear Editor,
Ajoy Mohan et al. [1] propose microalbuminuria and hemoglobin (Hb) as strong predictors of severe diabetic eye diseases - an important practical issue for laboratories. The authors have measured microalbumin in an early morning spot urine sample and calculated the albumin excretion for 24 hours. I would like to highlight the following points.
Firstly, the measurement accuracy must be clinically/optimally acceptable for any analyte when used for risk prediction. The authors have chosen the first morning void spot urine to measure albumin, which is the best sample approach. [2] But they calculated the albumin excretion for 24 hours, which is error prone. The preferred method of screening for microalbuminuria is measurement of the urine albumin to creatinine ratio (ACR) in the first morning spot urine. [3],[4] ACR reduces the variation from urine volume variability and the inconvenience of an error-prone 24-hour collection. The variation of albumin concentration in urine is more than 40% when it is expressed as mg/L. [5] [This means the true result of 50 mg/L may vary between 20 and 70 mg/L and it is apparent that the probability of misclassification into normal albumin is high (microalbuminuria: 30-300 mg/L)]. This is the rationale of requirement of multiple assays to confirm microalbuminuria, in order to improve the accuracy of the result as recommended by various clinical professional bodies such as the National Kidney Foundation (NKF), the American Diabetes Association (ADA), National Institute of Clinical Excellance (NICE), and others. In case a specific individual is followed over time with serial urine samples, the ACR may offer an advantage over albumin concentration alone.
Secondly, the currently used automated hematology cell counters adopt electrical impedance technique only to count the cells in the whole blood and not to directly measure the Hb concentration. Instead, spectrophotometry/complicated calculation is used to derive Hb concentration from the whole red blood cells. The authors mention "serum Hb" instead of blood Hb in their conclusion, in addition to the statement of non-existent method used for the measurement of Hb, which confuses the readers. Optimally achievable accuracy and consistency are of paramount importance for risk prediction testing. Participation in quality assurance program and accreditation for medical testing program also ensure that Hb and microalbuminuria testing is performed at an accepted standard, since their study results revolve around the urine albumin and blood Hb concentrations. Unfortunately, vital method details are missing in this paper to evaluate the scientific soundness of their study.
| References | |  |
| 1. | Ajoy Mohan VK, Nithyanandam S, Idiculla J. Microalbuminuria and low hemoglobin as risk factors for the occurrence and increasing severity of diabetic retinopathy. Indian J Ophthalmol 2011;59:207-10.  [ PUBMED]  |
| 2. | Witte EC, Lambers Heerspink HJ, de Zeeuw D, Bakker SJ, de Jong PE, Gansevoort R. First morning voids are more reliable than spot urine samples to assess microalbuminuria. J Am Soc Nephrol 2009;20:436-43. [ PUBMED] [ FULLTEXT] |
| 3. | Jafar TH, Chaturvedi N, Hatcher J, Levey AS. Use of albumin creatinine ratio and urine albumin concentration as a screening test for albuminuria in an Indo-Asian population. Nephrol Dial Transplant 2007;22:2194-200. [ PUBMED] [ FULLTEXT] |
| 4. | Justesen T, Petersen J, Ekbom P, Damm P, Mathiesen E. Albumin-to-creatinine ratio in random urine samples might replace 24-h urine collections in screening for micro- and macroalbuminuria in pregnant woman with type 1 diabetes. Diabetes Care 2006;29:924-5. |
| 5. | Greg Miller W, Bruns DE, Hortin GL, Sandberg S, Aakre KM, McQueen MJ, et al. Current issues in measurement and reporting of urinary albumin excretion. On behalf of the National Kidney Disease Education Program-IFCC Working Group on Standardization of Albumin in Urine. Clin Chem 2009;55:24-38. |
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