MAGNESIUM
Serum magnesium constitutes only a small fraction of the total body stores and may not predict magnesium status correctly.
From a physiologic perspective, magnesium directs protein digestion, by polarizing minerals associated with protein digestion, from the entrance of protein into the body to its final deposition in the cell.
Approximately 40-60 % of the magnesium is found in the skeleton for bone formation, 20% is found in the muscle, 30% is found in the intracellular cytoplasm, with only 1 % of the magnesium found in the serum.
Magnesium affects membrane permeability, nerve impulses, muscle contraction, intracellular fluid regulation, activation of enzyme systems, where magnesium acts as a metallic cofactor in over 300 enzymatic reactions.
Regulates protein synthesis, carbohydrate metabolism, nucleic acid synthesis, and blood viscosity.
Magnesium along with sodium, potassium and calcium regulate neuromuscular irritability and the mechanism for clotting.
Less then 2% of calcium, magnesium and phosphates are found in the plasma and extracellular fluid and are controlled in narrow limits.
Albumin accounts for 70% of the bound calcium.
Magnesium also binds to albumin and since it has a lower specificity for the receptors it creates more free magnesium in the plasma.
Magnesium and calcium are very much linked in their body functions and a deficiency in either one will have an adverse affect on the other. Especially since calcium needs magnesium to be absorbed thru the intestinal membrane as well as needing magnesium for calcium metabolism.
For example, a magnesium deficiency will cause calcium to migrate out of the bone and into soft tissues such as the aorta and kidneys. 95% of all magnesium that is filtered thru the glomerulus is reabsorbed by the tubules where parathormone enhances tubular reabsorption of magnesium.
When there is a deficiency of magnesium you will see a decrease in urine stores before serum stores. Please note that even when magnesium is in a 20% depleted state, magnesium levels in the serum will appear normal.
Calcium, magnesium and phosphates continuously enter the plasma via the kidney, the intestinal brush borders, and the ruffled border from the bones. Steady states of calcium, magnesium, and phosphorus approximate urine loss against intestinal absorption and skeletal mineral apposition against mineral absorption.
Magnesium in the cells is complexed to phosphates, citrates and anions such as ATP, AMP and ADP (such as MgATP2-)
Magnesium also plays a key role in the hormonal regulation of insulin, estrogen and thyroid hormones.
Magnesium also stimulates secretions from the parathyroids and adrenal cortex (corticosteroids).
Magnesium is also affected just the way calcium is to parathormone (enhances distal tubular reabsorption of magnesium) and to a lesser degree calcitonin.
In fact, calcium, magnesium, and phosphates are depressed in vitamin D deficiencies and increased with vitamin D excess.
Magnesium is used in the treatment of elevated cholesterol and triglycerides, muscular contraction, hypertension (A causal relation between decreased Mg2+ content of cardiac muscle/coronary arteries and nonocclusive sudden-death ischemic heart disease has been proposed) and premenstrual syndrome. Magnesium is indicated in collagen and connective tissue diseases, inflammatory disorders, migraines, general endocrine function and neurological and psychosomatic disorders.