Quick Review Cards for Medical Laboratory Science

Other Electrolytes Clinical Chemistry Review 95

ANALYTE REFERENCE RANGE CLINICAL SIGNIFICANCE OTHER

Magnesium
(Mg2+)

Calcium
(Ca2+)

1.6–2.6 mg/dL

Total: 8.6–10 mg/dL

Ionized: 4.60–

5.08 mg/dL

↑due to renal failure, ↑intake (e.g.,

antacids), dehydration, bone cancer,

endocrine disorders. Can cause cardiac

abnormalities, paralysis, respiratory

arrest, coma.

↓due to severe illness, GI disorders, en-

docrine disorders, renal loss. Can lead to

cardiac arrhythmias, tremors, tetany,

paralysis, psychosis, coma. Rare in non-

hospitalized patients.

↑with primary hyperparathyroidism,

cancer, multiple myeloma. Can cause

weakness, coma, GI symptoms, renal

calculi.

↓with hypoparathyroidism, malabsorption,

vitamin D deficiency, renal tubular

acidosis. Leads to tetany (muscle spasms),

seizures, cardiac arrhythmias.

Essential cofactor for many enzymes.

10× more concentrated in RBCs. Avoid

hemolysis. EDTA, citrate, oxalate bind Mg2+.

Colorimetric methods are most common.

Most abundant mineral in body. 99% in

bones. Regulated by parathyroid hormone

(PTH), vitamin D, calcitonin. Anticoagu-

lants other than heparin bind Ca2+.

Colorimetric methods for total Ca2+.

Ionized (free) Ca2+is biologically active

form, better indicator of Ca2+ status.

Measured by ISE. Affected by pH & temp.

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