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Molybdenum is an essential trace element found in the daily diet. It is a cofactor for some enzymes important in nitrogen metabolism (aldehyde dehydrogenase, xanthine oxidase, NADH dehydrogenase). Due to the wide distribution of molybdenum in the environment and particularly in plant materials, molybdenum deficiency is rare in adults with normal, diverse diets. Typical molybdenum intake in most geographic locations is between 45 mcg/day and 90 mcg/day.(1) Urine is the primary source of excretion, though excesses are sometimes excreted by the biliary route.
Molybdenum deficiency associated with parenteral nutrition is indicated by symptoms such as stunted growth, reduced appetite, tachycardia, tachypnea, blindness, and coma. These symptoms can be corrected by introducing molybdenum supplementation.(3) Molybdenum cofactor disease is a severe genetic disorder that is due to defective mutations in the MOCS1, MOCS2, and GEPH genes.
Molybdenum toxicity is rare and usually related to molybdenum mining exposure; however it but has been observed in cases of intake >400 mcg/day. Molybdenum interferes with copper uptake; molybdenum toxicity is predominantly due to copper deficiency (hypochromic anemia and neutropenia) and inhibition of xanthine oxidase (uric acid accumulation).
Urine molybdenum 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. Prosthetic devices produced by Depuy Company, Dow Corning, Howmedica, LCS, PCA, Osteonics, Richards Company, Tricon, and Whiteside typically are made of chromium, cobalt, and molybdenum. This list of products is incomplete, and these products change occasionally; see prosthesis product information for each device for composition details.(4-5)
Monitoring of parenteral nutrition
Monitoring metallic prosthetic implant wear
As an indicator of molybdenum cofactor disease
Molybdenum excretion rates are variable and related to dietary intake. Evaluation of 124 healthy adults by Mayo Clinic suggested a reference range of 22 to 173 mcg/specimen.
Prosthesis wear is known to result in increased circulating concentration of metal ions.(5-6) No increase in urine molybdenum concentration is evident with a prosthetic device in good condition. Urine concentrations >200 mcg/specimen in a patient with a molybdenum-based implant suggest significant prosthesis wear. Increased urine trace element concentrations in the absence of corroborating clinical information do not independently predict prosthesis wear or failure.
Urine molybdenum <20 mcg/specimen indicates potential deficiency.
Increased urine molybdenum may be seen in acute viral hepatitis, chronic active hepatitis, alcoholic liver disease, and other forms of liver inflammation.
Molybdenum is a trace metal commonly used in alloys and readily present in the environment, thus, contamination of the specimen must be avoided. Failure to use metal-free collection procedures and devices may cause falsely increased results. See Specimen Required for collection and processing information.
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 should not be collected for 96 hours.
1. Department of Human Service, Centers for Disease Control and Prevention. Third National Report on Exposure to Environmental Chemicals (NHANES). NCEH Publication 05-0570. July 2005
2. Shenkin A, Baines M, Fell GS, Lyon TDG: Vitamins and trace elements. In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Edited by CA Burtis, ER Ashwood, DA Bruns. St. Louis, Elsevier Saunders, 2006, p 1132
3. Witzleb WC, Ziegler J, Krummenauer F, et al: Exposure to chromium, cobalt and molybdenum from metal-on-metal total hip replacement and hip resurfacing arthroplasty. Acta Orthop 2006;77:697-705
4. Reiss J, Johnson J: Mutations in the molybdenum cofactor biosynthetic genes MOCS1, MOCS2, and GEPH. Hum Mutat 2003 June;21:569-576
5. Chao EY, Prichard D, Moyer TP: Metal ion release in patients with porous coated megaprostheses. J Orthop Res 1995;11:A29
6. 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
7. Lhotka C, Szekes T, Stefan I, et al: Four-year study of cobalt and chromium blood levels in patients managed with two different metal-on-metal total hip replacements. J Orthop Res 2003; 21:189-195