MAGNESIUM (Mg++)

INTRODUCTION:  Magnesium is the fourth most abundant cation in the body and second most prevalent intracellular cation. Magnesium is mainly seen in intracellular fluid. Total body magnesium is about 25 g, 60% of which is complexed with calcium in bone.  One-third of skeletal magnesium is exchangeable with serum.  Magnesium orally produces diarrhea; but intravenously it produces CNS depression.

REQUIREMENT:  The requirement is about 400 mg/day for men and 300 mg/day for women. Doses above 600 mg may cause diarrhea. More is required during lactation. Major sources are cereals, beans, leafy vegetables and fish.

NORMAL SERUM LEVEL OF MAGNESIUM: Normal serum level Mg++ is 1.8-2.2 mg/dl. Inside the RBC, the magnesium content is 5 mEq/L. In muscle tissue Mg++ is 20 mEq/L. About 70% of magnesium exists in free state and remaining 30% is protein-bound (25% to albumin and 5% to globulin).  Homeostasis is maintained by intestinal absorption as well as by excretion by kidney.  Magnesium is reabsorbed from loop of Henle and not from proximal tubules.

FUNCTIONS OF MAGNESIUM:  1.  Mg++ is the activator of many enzymes requiring ATP. Alkaline phosphatase, hexokinase, fructokinase, phosphofructokinase, adenyl cyclase, cAMP dependent kinases among others. need magnesium.

2. Neuromuscular irritability is lowered by magnesium.

3. Insulin-dependent uptake of glucose is reduced in magnesium deficiency. Magnesium supplementation improves glucose tolerance.

 

RELATED;

1.  PLASMA PROTEINS

2. ENZYMES

3. VITAMIN C

4.  VITAMIN A

5.  VITAMINS AND MINERALS

6.  BIOCHEMISTRY

REFERENCES