Microalbumin in Human Urine with Roche c502

Detection of Microalbumin in Human Urine with Roche c502

Test Name: In vitro test for the quantitative determination of albumin in human urine on Roche/Hitachi cobas c systems.
Method Name: The Roche Diagnostics Microalbumin assay is based on the immunoturbidimetric method. In the assay, anti‑albumin antibodies react with the antigen in the sample to form antigen/antibody complexes which, following agglutination, are measured turbidimetrically.
Results: Technical Range: 12-400 mg/L
Reportable Range: 12-361.5 mg/L
Reference Ranges: <30 mg/L
Clinical Significance: Albumin is a non-glycosylated protein with a molecular weight of 66000 daltons. It is synthesized in liver parenchymal cells at a rate of 14 g/day. Quantitatively, albumin is normally the most important protein component (> 50 %) in plasma, CSF and urine. A small, but abnormal albumin excretion in urine is known as microalbuminuria. Causes of microalbuminuria can be glomerular (e.g., due to diabetic microangiopathy, hypertension, minor glomerular lesion), tubular (inhibition of reabsorption) or postrenal. Albumin is also a marker protein for various forms of proteinuria.

In selective glomerular proteinuria, 100-3000 mg albumin/g creatinine are excreted in the urine. Non-selective glomerular proteinuria is characterized by elevated excretion of high-molecular weight proteins (IgG more than 10 % of the albumin value). Prerenal proteinuria is recognized by a discrepancy between albumin and total protein (albumin accounting for less than 30 %, with concurrent elevation of total protein). Simultaneous elevation of albumin and microproteins is found in glomerulotubular proteinuria occurring due to overloading of tubular reabsorption in glomerulopathy (e.g., nephrotic syndrome), combined glomerular tubulointerstitial nephropathy or in renal failure following diabetic nephropathy or other causes (overflow proteinuria). Albumin has two main functions in plasma: maintaining the oncotic pressure (80 % due to albuminin plasma) and transport. It is the most important transport protein for substances having low water solubility (such as free fatty acids, bilirubin, metal ions, hormones and pharmaceuticals).

Depressed albumin levels are caused by hyperhydration, hepatocellular synthesis insufficiency, secretion disorders in the intravascular space, abnormal distribution between the intravascular and extravascular space, catabolism and loss of albumin, acute phase reactions and congenital analbuminemia.

Blood brain barrier disorders can be reliably quantified with the aid of the albumin CSF/serum ratio. Elevated albumin ratios are indicative of a blood brain barrier disorder.

By simultaneously determining IgG in CSF and serum while considering the individual albumin ratios, it is possible to differentiate between IgG originating from the blood and CNS-synthesized immunoglobulin. IgG predominates in multiple sclerosis, chronic HIV encephalitis, neurosyphilis and herpes simplex encephalitis.

Submission Criteria: For specimen collection and preparation, only use suitable tubes or collection containers. Only the specimens listed below were tested and found acceptable.
Use Spontaneous, 24‑hour urine or 2nd morning urine specimens.
Use no preservatives. Refrigerate specimen during collection.

The sample types listed were tested with a selection of sample collection tubes that were commercially available at the time of testing, therefore not all available tubes of all manufacturers were tested. Sample collection systems from various manufacturers may contain differing materials which could affect the test results in some cases.  When processing samples in primary tubes (sample collection systems), follow the instructions of the tube manufacturer.
Storage and Stability:    6 months at -20°C
1 month at 4-8°C
7 days at 20-25 °C

Rejection Criteria: Rejection criteria include but are not limited to:
1. Mismatched requisitions
2. Specimens without patient identifiers
3. Specimens stored or shipped incorrectly
4. Specimens collected using expired tubes/cups
5. Specimens with inappropriate preservatives such as formalin or formaldehyde, disinfectant, or detergent added
6. Specimens not analyzed within the appropriate time frame
7. Specimens with quantity not sufficient
8. Hematuria
9. Specimens contaminated with fecal matter10.
Specimens submitted without approval
Authorization: Diagnostic testing can only be performed with approval from an authorized provider/agency.
Turn Around Time: