Efficacy of Spot Urinary Albumin Excretion Test for the Detection of Early Nephropathy

  • Adeeba Fakhar Senior Registrar, Department of Nephrology, Pakistan Institute of Medical Sciences, Islamabad
Keywords: Albuminuria, Diabetes mellitus, Microalbumnuria, Nephropathy, Proteinuria, Spot urinary albumin


Objective: To compare the effectiveness of spot urinary microalbumin excretion for detection of early diabetic nephropathy in comparison with 24 hours urinary proteins in patients with diabetes mellitus.
Materials and Methods: The study was conducted at Nephrology Department of Pakistan Institute of medical Sciences, Islamabad. It included diagnosed cases of type 1 or 2 diabetes mellitus, (with type 2 diabetes of any duration and type 1 diabetes of more than 5 years duration) who tested negative for overt albuminuria on standard urinary dipstick done on two occasions. Each patient was provided a plastic container with capacity of 4000 ml for 24 hours collection of urine. The study group subjects were requested to provide early morning urine sample for spot urine test. Urinary microalbumin was determined by the immunoturbidimetric method. 24-hour urinary albumin excretion was determined by photometric test according to biuret method. SPSS version 12 was used to record and analyze the gathered data. Descriptive statistic and frequencies of the spot urine albumin and 24 hours urinary albumin were measured. The sensitivity, specificity, negative predictive value, positive predictive value, accuracy and efficacy of spot urine microalbumin test was calculated in comparison to 24-hour urine protein test.
Results: Out of 289 patients of Diabetes mellitus included in the study, 39 (13.5%) had type 1 Diabetes mellitus and 250 (86.5%) had type 2 Diabetes mellitus. The mean age of the patients was 54.079.5 years. Among total patients 113 (39.1%) patients had positive 24-hour urine protein and 98 (33.9%) had positive spot urine microalbumin test. The sensitivity, specificity, positive predictive value and negative predictive value of the spot urinary microalbumin test in comparison to 24-hour urine protein test was 83%, 97.7%, 96% and 90% respectively. In total spot urinary microalbumin test was accurate in 92% cases. When the results of spot urine microalbumin test and 24-hour urinary protein test were compared using the chi-square test, it was found that patients with a positive spot urine microalbumin test had a statistically significant probability of having a confirmed diabetic nephropathy on 24-hour urinary protein test; p= 0.00.
Conclusion: Spot urine microalbumin test is a highly sensitive and specific tool in the diagnosis of early diabetic nephropathy with high positive predictive value. Spot urine microalbumin test offers the advantage of speed, simplicity and early diagnosis. Spot urine microalbumin test has acceptable accuracy as compared to 24-hour urine protein test. 

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