TEST CATALOG ORDERING & RESULTS SPECIMEN HANDLING CUSTOMER SERVICE EDUCATION & INSIGHTS
Test Catalog

Test ID: ALCRU    
Aluminum/Creatinine Ratio, Random, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

Monitoring aluminum exposure when a 24-hour urine cannot be collected

 

Monitoring metallic prosthetic implant wear when a 24-hour urine cannot be collected

 

This test is not an acceptable substitute for serum aluminum measurements and is not recommended for routine aluminum screening.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Under normal physiologic conditions, the usual daily dietary intake of aluminum (5-10 mg) is completely eliminated. Excretion is accomplished by avid filtration of aluminum from the blood by the glomeruli of the kidney. Patients in renal failure (RF) lose the ability to clear aluminum and are candidates for aluminum toxicity. Many factors increase the incidence of aluminum toxicity in RF patients:

-Aluminum-laden dialysis water can expose dialysis patients to aluminum.

-Aluminum-laden albumin can expose patients to an aluminum burden they cannot eliminate.

-The dialysis process is not highly effective at eliminating aluminum.

-Aluminum-based phosphate binder gels are administered orally to minimize phosphate accumulation; a small fraction of this aluminum may be absorbed and accumulated.

 

If it is not removed by renal filtration, aluminum accumulates in the blood where it binds to proteins such as albumin and is rapidly distributed through the body. Aluminum overload leads to accumulation of aluminum at 2 sites: brain and bone. Brain deposition has been implicated as a cause of dialysis dementia. In bone, aluminum replaces calcium at the mineralization front, disrupting normal osteoid formation.

 

Urine aluminum concentrations are likely to be increased above the reference range in patients with metallic joint prosthesis. Prosthetic devices produced by Zimmer Company and Johnson and Johnson typically are made of aluminum, vanadium, and titanium. This list of products is incomplete, and these products change occasionally; see prosthesis product information for each device for composition details.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

0-17 years: not established

> or =18 years: <14 mcg/g Creatinine

Interpretation Provides information to assist in interpretation of the test results

Daily excretion more than 10 mcg/24 hours indicates exposure to aluminum. Prosthesis wear is known to result in increased circulating concentration of metal ions.(1) Modest increase (10-20 mcg/24 hours) in urine aluminum concentration is likely to be associated with a prosthetic device in good condition. Urine concentrations more than 50 mcg/24 hours in a patient with an aluminum-based implant, not undergoing dialysis, suggest significant prosthesis wear. Increased urine trace element concentrations in the absence of corroborating clinical information do not independently predict prosthesis wear or failure.

 

In renal failure, the ability of the kidney to excrete aluminum decreases, while the exposure to aluminum increases (aluminum-laden dialysis water, aluminum-laden albumin, and aluminum-laden phosphate binders).

 

Patients receiving chelation therapy with desferrioxamine (for iron- or aluminum-overload states) also excrete considerably more aluminum in their urine than normal.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Falsely increased results may be obtained if the specimen is collected in nonacid-washed polypropylene collection vessels or if metal caps are used to seal the container. Preanalytical steps (specimen collection and transport) are the most likely processes that can affect the quality of trace metals analysis in clinical samples. Specimens must be collected and processed following the instructions in the Mayo laboratories trace metal analysis specimen collection and transport document.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Liu TK, Liu SH, Chang CH, Yang RS: Concentration of metal elements in the blood and urine in the patients with cementless total knee arthroplasty. Tohoku J Exp Med 1998;185:253-262

2. O'Shea S, Johnson DW: Review article: Addressing risk factors in chronic kidney disease mineral and bone disorder: Can we influence patient-level outcomes? Nephrology 2009;14:416-427

3. Meyer-Baron M, Schuper M, Knapp G, van Thriel C: Occupational aluminum exposure: Evidence in support of its neurobehavioral impact. NeuroToxicology 2007;28:1068-1078

Special Instructions Library of PDFs including pertinent information and forms related to the test