Assays / Trace Metals/ Chromium

Chromium and chromium compounds are widely used in a number of industrial processes, such as chrome plating, pigment production, timber impregnation and photography. They are also present in small amounts in cement.
Chromium is thought to be an essential trace element which, although reasonably abundant in the environment, is present in the human body in relatively small amounts. Measurement of the element is difficult in view of the low concentrations and the possibility of contamination. It is probable that the element is poorly absorbed in its inorganic form, but more bioavailable when present as an organic complex. It may be transported in the blood bound to transferrin.

Deficiency
Chromium deficiency was first documented in animals when it resulted in impaired glucose tolerance. Deficiency of an organic complex of chromium, the so-called glucose tolerance factor, was considered to be responsible. A deficiency state in man was only revealed by the increasing use of total parenteral nutrition, (TPN) where patients presumed to be deficient in this element developed insulin resistance and neuropathy. In animals chromium deficiency has also been shown to impair growth and fertility and to be associated with hypercholesterolaemia.
In clinical practice there is some evidence that diabetes mellitus and hypercholesterolaemia may be associated with chromium deficiency, and evidence that supplementation may improve these conditions.

Toxicity
Chromium salts may have acute and chronic effects, producing both corrosive damage to mucus membranes and skin ('chrome ulcers'), and also allergic responses. A serious long-term effect is the increased incidence of malignancy in respiratory organs amongst workers inhaling chromium dust or fumes. There may also be an increased incidence of gastrointestinal tumours.

Laboratory Indices
Measurement of serum chromium concentration is the best available index of excess exposure, and concentrations may still be high some weeks after the incident. Urine chromium concentrations decline rapidly after removal from exposure, but appropriately collected samples are suitable for occupational monitoring.
For the assessment of deficiency, please note the special sampling precautions that need to be taken. The considerable doubt regarding nutritional requirements for chromium, and the variable concentration of contaminating chromium in TPN fluids, suggest that regular monitoring of serum chromium in patients receiving long term TPN is desirable. Supplementation should be adjusted accordingly.

References
Anderson RA. Chromium metabolism and its role in disease processes in man. Clin Physiol Biochem 1986; 4: 31-41
Angerer J, Amin W, Heinrich-Ramm R, Szadkowski D, Lehnert G. Occupational exposure to metals. 1. Chromium exposure of stainless steel welders - biological monitoring. Int Arch Occup Environ Health 1987; 59: 503-12
Mertz W. Chromium in human nutrition: a review. J Nutr 1993; 123: 626-33

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