Sorted By Test Name - Mayo Medical Laboratories

FMRBC
57272
MGS
8448
changes in calcium-, potassium-, and phosphate-homeostasis, which are associated with cardiac disorders
such as ventricular arrhythmias that cannot be treated by conventional therapy, increased sensitivity to
digoxin, coronary artery spasms, and sudden death. Additional concurrent symptoms include
neuromuscular and neuropsychiatric disorders. Conditions associated with hypomagnesemia include
chronic alcoholism, childhood malnutrition, lactation, malabsorption, acute pancreatitis, hypothyroidism,
chronic glomerulonephritis, aldosteronism, and prolonged intravenous feeding
Useful For: Assessing the cause of abnormal serum magnesium concentrations Determining whether
the body is receiving adequate nutrition
Interpretation: With normal dietary intake of 200 mg to 500 mg of magnesium per day, urine
excretion is typically 30 mg/L to 210 mg/L in children and adults. The remainder of the dietary intake
passes through the gastrointestinal tract and is excreted in the feces. Decreased renal function, such as in
dehydration, diabetic acidosis, or Addison's disease, results in reduced output of magnesium. Poor diet
(alcoholism), malabsorption, and hypoparathyroidism result in low urine magnesium due to low uptake
from the diet. Chronic glomerulonephritis, aldosteronism, and drug therapy (cyclosporine, thiazide
diuretics) enhance excretion, resulting in high output of magnesium.
Reference Values:
0-15 years: 110-210 mg/L
> or =16 years: 29-107 mg/L
Clinical References: 1. Fenton TR, Eliasziw M, Lyon AW, et al: Low 5-year stability of
within-patient ion excretion and urine pH in fasting-morning-urine specimens. Nutr Res
2009;29:320–326 2. Mircetic RN, Dodig S, Raos M, et al: Magnesium concentration in plasma,
leukocytes and urine of children with intermittent asthma. Clin Chim Acta 2001;312:197–203
Magnesium, RBC
Reference Values:
3.5 – 7.1 mg/dL
Test Performed by: Medtox Laboratories
402 W. County Road D
St. Paul, MN 55112
Magnesium, Serum
Clinical Information: Magnesium along with potassium is a major intracellular cation. Magnesium is
a cofactor of many enzyme systems. All adenosine triphosphate (ATP)-dependent enzymatic reactions
require magnesium as a cofactor. Approximately 70% of magnesium ions are stored in bone. The
remainder is involved in intermediary metabolic processes; about 70% is present in free form while the
other 30% is bound to proteins (especially albumin), citrates, phosphate, and other complex formers. The
serum magnesium level is kept constant within very narrow limits. Regulation takes place mainly via the
kidneys, primarily via the ascending loop of Henle. Conditions that interfere with glomerular filtration
result in retention of magnesium and hence elevation of serum concentrations. Hypermagnesemia is found
in acute and chronic renal failure, magnesium overload, and magnesium release from the intracellular
space. Mild-to-moderate hypermagnesemia may prolong atrioventricular conduction time. Magnesium
toxicity may result in central nervous system (CNS) depression, cardiac arrest, and respiratory arrest.
Numerous studies have shown a correlation between magnesium deficiency and changes in calcium-,
potassium-, and phosphate-homeostasis which are associated with cardiac disorders such as ventricular
arrhythmias that cannot be treated by conventional therapy, increased sensitivity to digoxin, coronary
artery spasms, and sudden death. Additional concurrent symptoms include neuromuscular and
neuropsychiatric disorders. Conditions that have been associated with hypomagnesemia include chronic
alcoholism, childhood malnutrition, lactation, malabsorption, acute pancreatitis, hypothyroidism, chronic
glomerulonephritis, aldosteronism, and prolonged intravenous feeding.
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