Magnesium disorders

Magnesium is the second most abundant intracellular cation. Magnesium serves as an essential cofactor for numerous enzymes and in many biochemical reactions, including reactions involving adenosine triphosphate (ATP).17 Magnesium disorders can be multifactorial and can be related to renal function, disease... 

Uses and Economic Aspects. Magnesium bromide is used in medicine as a sedative in treatment of nervous disorders, in electrolyte paste for magnesium dry cells, and as a reagent in organic synthesis reactions. The price of magnesium bromide hexahydrate in January 1995 was 5.51/kg (33). 

Other Calcium Disorders. In addition to hypocalcemia, tremors, osteoporosis, and muscle spasms (tetary), calcium deficiency can lead to rickets, osteomalacia, and possibly heart disease. These, as well as Paget s disease, can also result from faulty utilization of calcium. Calcium excess can lead to excess secretion of calcitonin, possible calcification of soft tissues, and kidney stones when combined with magnesium deficiency. 

OtherMa.gnesium Disorders. Neuromuscular irritabHity, convulsions, muscle tremors, mental changes such as confusion, disorientation, and haHucinations, heart disease, and kidney stones have aH been attributed to magnesium deficiency. Excess Mg " can lead to intoxication exemplified by drowsiness, stupor, and eventuaHy coma. 

Because of very high dielectric constants k > 20, 000), lead-based relaxor ferroelectrics, Pb(B, B2)02, where B is typically a low valence cation and B2 is a high valence cation, have been iavestigated for multilayer capacitor appHcations. Relaxor ferroelectrics are dielectric materials that display frequency dependent dielectric constant versus temperature behavior near the Curie transition. Dielectric properties result from the compositional disorder ia the B and B2 cation distribution and the associated dipolar and ferroelectric polarization mechanisms. Close control of the processiag conditions is requited for property optimization. Capacitor compositions are often based on lead magnesium niobate (PMN), Pb(Mg2 3Nb2 3)02, and lead ziac niobate (PZN), Pb(Zn 3Nb2 3)03. 

Magnesium cadmium, alloy (MgCd3), 128 alloy (Mg3Cd), 129 Magnetic entropy, 132 disordering, 131... 

Any time an ABG is analyzed it is wise to concurrently inspect the serum chemistry values to calculate the anion gap. The body does not generate an anion gap to compensate for a primary disorder. As such, if the calculated anion gap exceeds 12 mEq/L (mmol/L) there is a primary metabolic acidosis regardless of the pH or the serum HC03 concentration. The anion gap may be artificially lowered by decreased serum albumin, multiple myeloma, lithium intoxication, or a profound increase in the serum potassium, calcium, or magnesium. 

Rajput, S.S., Prasad, R., Singru, R.M., Triftshauser, W., Eckert, A., Kogel, G., Kaprzyk, S. and Bansil, A. (1993) A study of the Fermi surface of lithium and disordered lithium-magnesium alloy theory and experiment, J. Phys. Condens. Matter, 5,6419-6432. 

Laboratory tests for identifying disorders that may cause or worsen HF include compete blood count serum electrolytes (including calcium and magnesium) renal, hepatic, and thyroid function tests urinalysis lipid... 

Fluid and electrolyte homeostasis is maintained by feedback mechanisms, hormones, and many organ systems and is necessary for the body s normal physiologic functions. Disorders of sodium and water, calcium, phosphorus, potassium, and magnesium homeostasis are addressed separately in this chapter. 

Hypomagnesemia is usually associated with disorders of the intestinal tract or kidneys. Drugs (e.g., aminoglycosides, amphotericin B, cyclosporine, diuretics, digitalis, cisplatin) or conditions that interfere with intestinal absorption or increase renal excretion of magnesium can cause hypomagnesemia. 

See Chap. 52, Disorders of Sodium and Water Homeostasis, authored by James D. Coyle and Melanie S. Joy Chap. 53, Disorders of Calcium and Phosphorus Homeostasis, authored by Amy Barton Pai, Mark Rohrscheib, and Melanie S. Joy and Chap. 54, Disorders of Potassium and Magnesium Homeostasis, authored by Donald F. Brophy and Todd W. B. Gehr, for a more detailed discussion of this topic... 

Subcutaneous administration of -hexanc at 143 mg/kg/day for 30 days has been reported to decrease the threshold for ventricular fibrillation in perfused hearts from male Wistar rats (Khedun et al. 1996). Myocardial magnesium and potassium levels were reduced in treated rats. When these levels were corrected by supplementation, the ventricular fibrillation potential was still reduced. Histological alterations (disordered myocardial Z-bands) were also observed in exposed rats. 

Mineral deficiencies are not uncommon and can have quite a variety of causes—e. g., an unbalanced diet, resorption disturbances, and diseases. Calcium deficiency can lead to rickets, osteoporosis, and other disturbances. Chloride deficiency is observed as a result of severe Cr losses due to vomiting. Due to the low content of iodine in food in many regions of central Europe, iodine deficiency is widespread there and can lead to goiter. Magnesium deficiency can be caused by digestive disorders or an unbalanced diet—e.g., in alcoholism. Trace element deficiencies often result in a disturbed blood picture—i. e., forms of anemia. 

Electrolyte disorders In patients with hypokalemia or hypomagnesemia, toxicity may occur despite serum digoxin concentrations less than 2 ng/mL, because potassium or magnesium depletion sensitizes the myocardium to digoxin. Therefore, it is desirable to maintain normal serum potassium and magnesium concentrations in patients being treated with digoxin. 

Electrolyte disturbances Correct potassium or magnesium deficiency before therapy begins as these disorders can exaggerate the degree of QTc prolongation and increase the potential for torsades de pointes. 

Magnesium bromide occurs in sea water, surface and subterranean brines, and salt deposits. It is an electrolyte component in certain dry cells. In medicine, it is a sedative and anticonvulsant for treatment of nervous disorder. It also is used in organic synthesis forming several addition compounds. 

Neurological symptoms, which tend to appear in the first week of therapy, consist of dizziness, confusion, irritability, psychotic behavioral changes, and even suicidal ideation. Cycloserine is contraindicated in patients with underlying psychiatric and seizure disorders. Other side effects include occasional peripheral neuropathy and low magnesium levels. 

Molin G.M., Saxena S.K., and Brizi E. (1991) Iron-magnesium order-disorder in an orthopyroxene crystal from the Johnstown meteorite. EarthPlanet. Sci. Lett. 105, 260-265. 

Contraindications Allergy to tartrazine dye, bleeding disorders, GI bleeding or ulceration, history of hypersensitivity to choline magnesium trisalicylate, aspirin, or NSAIDs. 

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