Dr. med. Dirk Manski

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Magnesium – Serum Blood Test

The human body contains about 25 g magnesium, 99% is localized intracellularly. Magnesium is essential in many metabolic pathways as coenzyme or enzyme component. Furthermore, magnesium is stabilizes the membrane potential and acts as a second messenger in signal transduction.

Standard value:

0.7–1.1 mmol/l.

Laboratory test method:

Spectrophotometry after color reaction.


Control of therapy with diuretics or nephrotoxic drugs such as aminoglycosides or cisplatin. Gastointestinal, muscular or cardiac complaints. Suspected intoxication with magnesium.

Differential Diagnosis of Hypomagnesemia:

Hypomagnesemia is a low concentration of magnesium in the blood leeding to instability of the membrane potential with nervousness, cardiac arrhythmias and muscle cramps. Causes are insufficient intake, gastrointestinal loss, acute pancreatitis, renal loss (Bartter syndrome, polyuria after acute renal failure, diuretics, treatment with aminoglycosides or cisplatin), hyperthyroidism, hyperparathyroidism, hyperaldosteronism or bone metastases.

Differential Diagnosis of Hypermagnesemia:

Hypermagnesemia is a high concentration of magnesium in the blood, in most cases without symptoms. Only very high concentrations above 4 mmol/l lead to cardiac and neurological symptoms. Causes are iatrogenic (infusions, antacids, laxatives), renal insufficiency, hypothyroidism or adrenocortical insufficiency.

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Guder, W. G. & Nolte, J.
Das Laborbuch für Klinik und Praxis
Urban + Fischer, 2009

Siegenthaler 1988 SIEGENTHALER, W. ; SIEGENTHALER, W. (Hrsg.):
Differentialdiagnose innerer Krankheiten.
Georg Thieme Verlag, Stuttgart, New York., 1988

  Deutsche Version: Elektrolyte im Serum: Magnesium