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Test Code MAU (timed), RMALB (random) Microalbumin, Quantitative, Urine

Specimen Type

Urine, timed (24 hour) or random collection

Container

Urine, random or timed 24 hour

Preferred Volume

4 mL

UCMC Collection Instructions

For timed specimens, send 10 mL of a well mixed sample. Indicate start and end times and total volume.
If collection duration is not specified, specimen will be considered a random sample. Any timed specimen less than 24 hours in duration may have compromised results. 

Availability

24/7

Turnaround Time

3 hours

STAT Availability

Not Available

Test Usage

Microalbuminuria testing is used to detect albuminuria in diabetes mellitus, pre-eclampsia, hypertension, and systemic lupus erythematosus. Its major role is to attempt to predict subsequent development of proteinuria, diabetic nephropathy, serious extrarenal cardiovascular disease, and early mortality in type I and/or II diabetes.

Test Methodology

Immunoturbidimetric

Additional Information

Microalbuminuria is defined as albumin excretion in the 30-300 mg/24 hr and 20-200mg/min range for timed (24 hour) urine specimens, or albumin/creatinine ratios in the 20-200mg/mg range for untimed (random) specimens. Overt albuminuria is defined as albumin excretion > 300 mg/24 hr and > 200mg/min for timed (24 hour) urine specimens, or albumin/creatinine ratios > 200mg/mg for untimed (random) urine specimens.
 

As there is considerable biologic variability in microalbumin excretion, it is recommended that all patients be evaluated for microalbuminuria based on more than an isolated determination on a single urine specimen (regardless of whether a timed or untimed urine specimen is used). Reports indicate that intraindividual biologic variability may be as high as 20 – 40% over the course of a one-month period. Moreover, various physiologic and pathologic factors are also known to potentially alter urinary microalbumin excretion, including: strenuous exercise, diurnal variation, pyrexia, urinary tract infection, menstruation, pregnancy, acute diuresis or fluid overload, hypertension, congestive heart failure, atherosclerosis, and postural (orthostatic) proteinuria. These factors must be taken into consideration when assessing patients for microalbuminuria, and before any clinical decision is made concerning the need to institute aggressive therapy (e.g., committing patients to a long-term course of management with ACE inhibitor antihypertensives). 
 

It is strongly advised that all positive test results for microalbuminuria be confirmed by follow-up testing on two additional urine specimens, collected on separate occasions. If a positive result is obtained by screening an untimed (random) urine specimen, it is preferable that the confirmatory quantitation of microalbumin be performed using timed (24 hour) urine collections. If confirmatory test results are consistent with microalbuminuria, and other physiologic or pathologic factors have been excluded as potential causes, these findings may be considered indicative of incipient nephropathy, and only then should aggressive therapy be considered.

CPT Code

RMALB: 82043

MAU: 82043

Test Includes

Random: Microalbumin and Creatinine
Timed: Microalbumin, Time and Volume Measurement

Critical Results

None

Reference Range

Random: albumin/creatinine ratio <30 µg/mg 
Timed: <30 mg/24 hours; excretion rate: <20 ug/min

Minimum Volume

2 mL

Fee Code

RMALB: 43853

MAU: 43853