Definition: is the serum concentration of magnesium.
Causes include inadequate intake of magnesium and increased absorption or excretion due to hypercalcemia caused by drugs such as furosemide.
Clinical manifestations are often due to hypokalemia and hypocalcemia that include: lethargy, tremors, tetany, seizures and arrhythmias. The treatment consists in the replacement of Magnesium.
The serum concentration of magnesium, even when measured with free magnesium ions, can be normal even with an intracellular or bone decrease in magnesium deposits.
The exhaustion produced by magnesium is usually the result of inadequate intake, plus deterioration of the kidneys or gastrointestinal absorption. There are numerous causes of clinically significant deficiency.
The causes of Hypomagnesemia
- Inadequate intake and excessive renal excretion with gastrointestinal losses
- Chronic diarrhea
Symptoms and signs
The clinical manifestations are: anorexia, nausea, vomiting, lethargy, weakness, personality changes, tetany (for example: positive Trousseau or Chvostek sign, spontaneous carpopedal spasm, hyperreflexia), muscle tremors and fasciculations.
Neurological signs, in particular tetany, correlate with the development of concomitant hypocalcemia, hypokalemia, or both, but are also compatible with hypocalcemia or hypokalemia. Severe hypomagnesemia can cause generalized tonic-clonic seizures, especially in children.
Considered in patients with high risk factors and with hypocalcemia or unexplained hypokalemia, hypomagnesemia is diagnosed by a concentration of magnesium in serum. Severe hypomagnesemia usually results in concentrations of associated hypocalcemia and hypocalciuria that are common.
Hypokalemia can increase urinary potassium excretion and metabolic alkalosis may be present. Magnesium deficiency should be suspected even when the serum magnesium level is normal in patients with hypocalcemia or hypokalemia.
The magnesium deficiency must also be suspected in patients with unexplained neurologic symptoms and alcoholism with chronic diarrhea, or after the use of cyclosporine, cisplatin – based chemotherapy, or prolonged therapy with amphotericin B or aminoglycosides.
* Magnesium salts orally
Treatment with magnesium salts is indicated when their deficiency is symptomatic or persistently. Patients with alcoholism are treated empirically.
Approximately twice the amount of the estimated deficit should be given in patients with intact renal function, since approximately 50% of the administered magnesium is excreted in the urine.
Magnesium salts orally (for example, Mg-gluconate 500 to 1000 mg orally three times a day) are given for 3 to 4 days. Oral treatment is limited by the onset of diarrhea.
Parenteral administration is reserved for patients with severe symptomatic hypomagnesemia who can not tolerate oral medications. Sometimes, a single injection is given in patients with alcoholism who are unlikely to adhere to oral therapy in progress.