Nickel (Ni) is a silvery white metal that is widely distributed in the earth's crust. Nickel is essential for the catalytic activity of some plant and bacterial enzymes but its role in humans has not been defined. Elemental nickel 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; is converted in the Mond process to nickel carbonyl, Ni(CO)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 nickel-cadmium rechargeable batteries, and is used as a catalyst in hydrogenation of oils.
Ni(CO)4, a liquid with low vapor pressure, is 1 of the most toxic chemicals known to man. Ni(CO)4 is absorbed after inhalation, readily crosses all biological membranes, and noncompetitively inhibits ATP-ase and RNA polymerase. When Ni(CO)4 vapor is inhaled it 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 Ni(CO)4 throughout the body. Urine is the specimen of choice for the determination of nickel exposure via inhalation.
Patients undergoing dialysis are exposed to nickel and accumulate nickel in blood and other organs; there appear to be no adverse health affects 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 nickel content has been associated with development of neoplasms of the respiratory system and nasal sinuses. Most reactions to nickel are localized skin sensitivity and allergic skin disorders that occur on contact with nickel-containing alloys. These reactions do not correlate to blood concentrations; patients experiencing skin sensitivity reactions to nickel are likely to have normal circulating concentrations of nickel.
Urine nickel is the test of choice for detecting nickel toxicity in patients exposed to nickel carbonyl
Values >2.0 ng/mL represent possible environmental or job-related exposure.
Toxic concentrations are > or =10 ng/mL.
Normal values are based on a Mayo Clinic study using healthy volunteers. Toxic values have been deduced from observation and unpublished internal study.
Clinical concern about nickel toxicity should be limited to patients with potential for exposure to toxic nickel compounds such as nickel carbonyl. Hypernickelemia, in the absence of exposure to that specific form of nickel, may be an incidental finding or could be due to specimen contamination.
Urine is the specimen of choice for detecting nickel toxicity.
This test cannot determine the source compound (eg, nickel sulfate) responsible for the exposure.
Specimen collection procedures for nickel 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 nickel 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.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Novelli EL, Rodrigues NL, Ribas BO: Superoxide radical and toxicity of environmental nickel exposure. Hum Exp Toxicol 1995;14:248-251
2. Nixon DE, Moyer TP, Squillace DP, McCarthy JT: Determination of serum nickel by graphite furnace atomic absorption spectrometry with Zeeman-effect background correction: values in a normal population and a population undergoing dialysis. Analyst 1989;114:1671-1674