Magnesium in plasma

Dawson and Heaton (DIO) determined magnesium in plasma and urine. A water-cooled burner was used with an air-acetylene flame. Good agreement was found with an ammonium phosphate precipitation method when allowance was made for the loss of magnesium during precipitation. 

Bone contains nearly all of the calcium (99%), most of the phosphate (85%), and much of the magnesium (55%) of the body. The concentrations of calcium, phosphate, and magnesium in plasma are dependent on the net effect of bone mineral deposition and resorption, intestinal absorption, and renal excretion. PTH and 1,25-dihydroxyvitamin D are the principal hormones regulating these three processes. 

Abernethy MH, Fowler RT. MiceUar improvement of the calmagite compleximetric measurement of magnesium in plasma. Cfin Chem 1982 28 520-2. 

In coronary arteriography, ionic monomers, because of their high osmolality and binding to calcium and magnesium in plasma, elicit more physiologic effects than nonionic monomers. The nonionic molecules do not combine calcium the chelators used in the formulation have less calcium binding capacity and the osmolality of nonionic monomers is only half that of the ionic monomers. Thus, nonionic contrast media cause fewer fluid shifts, less vasodilation, arrhythmia and fibrillation, and minimal cardiac depression. In an-... 

The methods in use in the author s laboratory for determination of calcium and magnesium in plasma and urine and in fecal and tissue ash are described below in detail. Willis (W2) has shown that absorption methods are also suitable. The methods described here have proved reliable in practice over several years of intensive use. 

The same dilution is used for analysis of both calcium and magnesium in plasma or serum, urine, tissue ash, and, where possible, in fecal ash. Occasionally a further dilution of the fecal ash solution may be appropriate where one element is in unusual concentration. 

Rayana, M. C. et al. 2008. IFCC guideline for sampling, measuring and reporting ionized magnesium in plasma. Clinical Chemistry and Laboratory Medicine 46 21-26. 

Hunt, B.J. (1969). The estimation of magnesium in plasma, muscle and bone, by atomic absorption spectrophotometry, Clin. Chem. 15, 979-996 lida, C., Uchida, T. and Kojima, I. (1980). Decomposition of bovine liver in a sealed teflon vessel for determination of metals by AAS, Anal. Chim. Acta, 113, 365 International Atomic Energy Agency (1978). Activation analysis of hair as an indicator of contamination of man by environmental trace element pollutants. A report of the co-ordinated research programme on nuclear based methods for analysis of pollutants in human hair. IAEA/RU/50... 

Petrow, H.G.and Cover, A. (1965). Magnesium in plasma, muscle and bone. Anal. Chem. 15,979-996. 

Magnesium. In the adult human, 50—70% of the magnesium is in the bones associated with calcium and phosphoms. The rest is widely distributed in the soft tissues and body duids. Most of the nonbone Mg ", like K", is located in the intracellular duid where it is the most abundant divalent cation. Magnesium ion is efftcientiy retained by the kidney when the plasma concentration of Mg fads in this respect it resembles Na". The functions of Na", K", Mg ", and Ca " are interrelated so that a deficiencv of Mg " affects the metaboHsm of the other three ions (26). Foods rich in magnesium are listed in Table 9. 

Magnesium deficiency has been long recognized, but hypermagnesia also occurs (Anderson and Talcott 1994). Magnesium can be determined in fluids by FAAS, inductively coupled plasma atomic emission spectrometry (ICP-AES) and ICP-MS. In tissue Mg can be determined directly by solid sampling atomic absorption spectrometry (SS-AAS) (Herber 1994a). Both Ca and Mg in plasma/serum are routinely determined by photometry in automated analyzers. 

Nygaard [752] has evaluated the application of the Spectraspan DC plasma emission spectrometer as an analysis tool for the determination of trace heavy metals in seawater. Sodium, calcium, and magnesium in seawater are shown to increase both the background and elemental line emission intensities. Optimum analytical emission lines and detection limits for seven elements are reported in Table 5.8. 

Several recent determinations of the alkali and alkaline earth metals in serum or urine have been reported. Barrett 29) determined potassium, sodium, and calcium in semm by diluting the samples with lanthanum chloride solution. Suttle and Field 3°) used atomic absorption spectroscopy to determine potassium and magnesium in sheep plasma. 

Many of the adverse effects of lithium can be ascribed to the action of lithium on adenylate cyclase, the key enz)nne that links many hormones and neurotransmitters with their intracellular actions. Thus antidiuretic hormone and thyroid-stimulating-hormone-sensitive adenylate cyclases are inhibited by therapeutic concentrations of the drug, which frequently leads to enhanced diuresis, h)rpoth)n oidism and even goitre. Aldosterone synthesis is increased following chronic lithium treatment and is probably a secondary consequence of the enhanced diuresis caused by the inhibition of antidiuretic-hormone-sensitive adenylate cyclase in the kidney. There is also evidence that chronic lithium treatment causes an increase in serum parathyroid hormone levels and, with this, a rise in calcium and magnesium concentrations. A decrease in plasma phosphate and in bone mineralization can also be attributed to the effects of the drug on parathyroid activity. Whether these changes are of any clinical consequence is unclear. 

Bond PA, Brooks BA, Judd A The distribution of lithium, sodium and magnesium in rat brain and plasma after various periods of administration of lithium in the diet. Br J Pharmacol 53 235-239, 1975... 

More than 300 enzyme systems of the human being are dependent on the presence of magnesium, hence the clinical importance of determining the input-output balance and homeostatic levels of this element. For estimation of Mg absorption two possible input avenues are considered, oral and intravenous injection, two output avenues, feces and urine, and the general pool in plasma. The input amounts are known by design ... 

Official methods have been published for the determination of exchangeable and extractable magnesium in soils [131]. Magnesium is extracted from the soil with 1M ammonium acetate and determined by atomic absorption spectrometry. The determination of magnesium in soils is also discussed under Multi-Metal Analysis of Soils in Sects. 2.55 (atomic absorption spectrometry), 2.55 (inductively coupled plasma atomic emission spectrometry), 2.55 (photon activation analysis) and 2.55 (ion chromatography). 

Gardner et al. [9] recognised that because component separations on size exclusion columns with distilled water are affected by chemical physical interactions as well as component molecular size, distilled water size exclusion chromatography will also fractionate dissolved metal forms. These workers interfaced distilled water size exclusion chromatography with inductively coupled argon plasma detection to fractionate and detect dissolved forms of calcium and magnesium in lake and river waters. 

About half the calcium and magnesium present in plasma is protein bound, the remainder being the ionised form. During occlusion the ionised... 

Haemolysis of the sample will cause a significant increase in plasma magnesium level. Lanthanum is added to samples and standard for convenience so that calcium and magnesium determinations may be made on each sample. 

---