NICRU - Clinical: Nickel/Creatinine Ratio, Random, Urine

Test Catalog

Test Name

Test ID: NICRU    
Nickel/Creatinine Ratio, Random, Urine

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

Urine nickel is the test of choice for detecting nickel toxicity in patients exposed to nickel carbonyl.

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

Nickel (Ni), a silvery white metal widely distributed in the earth's crust, is essential for the catalytic activity of some plant and bacterial enzymes but its role in humans has not been defined. Elemental Ni may be essential for life at very low concentrations and is virtually nontoxic.


Nickel is commonly used in industry. It is a pigment in glass, ceramics and fabric dyes. It is converted in the Mond process to nickel carbonyl, NiCO(4), and used as a catalyst in petroleum refining and in the plastics industry, is frequently employed in the production of metal alloys (which are popular for their anticorrosive and hardness properties) in Ni-cadmium rechargeable batteries, and is used as a catalyst in hydrogenation of oils. NiCO(4) is very toxic.


NiCO(4), a liquid with low vapor pressure, is one of the most toxic chemicals known to man. NiCO(4) is absorbed after inhalation, readily crosses all biological membranes, and noncompetitively inhibits ATP-ase and RNA polymerase. NiCO(4) binds avidly to hemoglobin with resultant inability to take up oxygen. The affinity for hemoglobin is higher than carbon monoxide. The binding to hemoglobin is the main transport mechanism for spreading NiCO(4) throughout the body. Urine is the specimen of choice for the determination of Ni exposure via inhalation.


Patients undergoing dialysis are exposed to Ni and accumulate Ni in blood and other organs; there appear to be no adverse health effects from this exposure. Hypernickelemia has been observed in patients undergoing renal dialysis. At the present time, this is considered to be an incidental finding as no correlation with toxic events has been identified. Routine monitoring of patients undergoing dialysis is currently not recommended.


Breathing dust high in Ni content has been associated with development of neoplasms of the respiratory system and nasal sinuses. Most reactions to Ni are localized skin sensitivity and allergic skin disorders that occur on contact with Ni-containing alloys. These reactions do not correlate to urine concentrations; patients experiencing skin sensitivity reactions to Ni are likely to have normal Ni excretion.

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

Males > or =18 years: <3.8 mcg/g creatinine

Females > or =18 years: <4.3 mcg/g creatinine

Interpretation Provides information to assist in interpretation of the test results

Values of 3.8 mcg/g creatinine and higher for males, or 4.3 mcg/g creatinine and higher for females, represent possible environmental or occupational exposure.


Nickel (Ni) concentrations above 50 mcg/g creatinine are of concern, suggesting excessive exposure.


Clinical concern about Ni toxicity should be limited to patients with potential for exposure to toxic Ni compounds such as nickel carbonyl. Hypernickelemia, in the absence of exposure to that specific form of Ni, may be an incidental finding or could be due to specimen contamination.

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

Specimen collection procedures for nickel (Ni) require special collection containers, rigorous attention to ultraclean specimen collection and handling procedures, and analysis in an ultraclean facility. Unless all of these procedures are followed, increased urinary Ni results may be an incidental and misleading finding.

High concentrations of gadolinium and iodine are known to interfere with most metals tests. If either gadolinium- or iodine-containing contrast media has been administered, a specimen cannot be collected for 96 hours.

This test cannot determine the source compound (eg, Ni sulfate) responsible for the exposure.

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

1. Moreno ME, Acosta-Saavedra LC, Mez-Figueroa D, et al: Biomonitoring of metal in children living in a mine tailings zone in Southern Mexico: A pilot study. Int J Hyg Environ Health 2010;213:252-258

2. Schulz C, Angerer J, Ewers U, et al: Revised and new reference values for environmental pollutants in urine or blood of children in Germany derived from the German Environmental Survey on Children 2003-2006 (GerES IV). Int J Hyg Environ Health 2009;212:637-647

Special Instructions and Forms Library of PDFs including pertinent information and consent forms, specimen collection and preparation information, test algorithms, and other information pertinent to test