DefinePK

Abstract

INTRODUCTION


More than 2000 years ago, the Greeks noted the medicinal properties of elements such as iodine, iron and arsenic. Since the industrial revolution and with this the increasing cxposure of man to metals, there has been increased interest in the biological aspects of metals and the recognition of their toxic states. Since the advent of atomic absorption spectrophotometry and many improve­ments in the technique over recent years, it has been possible to estimate more than 60 elements in various materials and at least 25 present in body fluids and tissues are known to be essential for health. Fourteen of these are termed trace elements as their concentration is less than 50 mg/kg body weight:
1. Iron
2. Iodine
3. Copper
4. Maganese
5. Zinc
6. Cobalt
7. Molybdenum
8. Selenium
9. Chromium
10. Tin
11. Vanadium
12. Flurine
13. Silicon
14. Nickel
Trace elements take part in bolic pathways, competing with each other for active metabolic sites, thus a change in concentra­tion of one element is expressed by a new balance worked out by the other competing trace elements. Evidence is accumulating that even the toxic element arsenic may have an essential role to play and may therefore be an essential element but no roles have yet been found for lead and aluminium which may therefore still be regarded as truly toxic elements. Amongst other elements, it is now known that even seemingly inert metals such as tungsten and tantalum when inspired as fine alloy dusts, appear in the blood and are ultimately excreted, and are therefore metabolized1. Studies have shown that an altered con­centration of a trace element can affect different systems. For example, copper deficiency has been associated with some forms of anaemia2, chromium deficiency with impaired glucose tolerance3, zinc deficiency with retarded growth4, and selenium deficiency with the cardiomyopathy, Keshan disease5, to mention but a few. The pos­sibility that a trace element abnormality can produce psychiatric illness has been considered in several studies6. The first real breakthrough providing evidence for the therapeutic potential of trace elements in neuropsychiatry came in 1948 with the use of lithium in the treatment of manic depressive psychosis7. This review is centered around the essential elements, copper, zinc and magnesium only, as the medical aspects of these metals have not been reviewed in any Pakistani journal.