Measurement of urine magnesium levels is used to evaluate pathological concentrations of serum magnesium, determine the adequacy of magnesium uptake, and assess the risk of kidney stones (along with the determination of other factors).
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Measurement of magnesium (Mg) levels is used as an indicator for the body's metabolic activity (such as carbohydrate metabolism, protein synthesis, nucleic acid synthesis, and muscle tissue contraction) and kidney function because 95% of magnesium which is filtered through the glomerulus is reabsorbed into the renal tubes. Most of the body's magnesium, an electrolyte, is concentrated in the bones, cartilage, and cells. In addition, magnesium is essential in the blood clotting mechanism. Magnesium regulates neuromuscular stimulation, acts as a cofactor that modifies many enzymes' activity, and significantly affects calcium metabolism. Magnesium along with potassium is the most important intracellular cations.
Symptoms of hypermagnesemia include lethargy, drowsiness, flushing, nausea, vomiting, speech disorders, hypotension, weakness or absence of tendon reflexes, and changes in electrocardiogram (such as prolongation of PR and QT interval, wide QRS, bradycardia), respiratory depression.
Magnesium-rich foods include seafood, meats, green vegetables, whole grains, and nuts. Excessive phosphate intake prevents the absorption of both magnesium and calcium.
Urine magnesium testing is useful in the evaluation of kidney disease and magnesium deficiency. In magnesium deficiency, urine magnesium decreases before serum magnesium.
Magnesium is an inhibitor of the growth of calcium crystals in the urine and contributes to the supersaturation of calcium oxalate and calcium phosphate. However, low magnesium in the urine is not considered a cause of kidney stones, nor is supplementation of magnesium an effective treatment to prevent kidney stone formation.
Possible Interpretations of Pathological Values
- Increase: Alcoholism, Bartter's syndrome, hypermagnesemia, nephrolithiasis. Medications: Aldosterone, cisplatin, corticosteroids, diuretics (ethacrynic acid), thiazides
- Decrease: Kidney disease, kidney stones, magnesium deficiency, osteoporosis, syndrome of inappropriate secretion of antidiuretic hormone
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
