Principles of the Reaction
Magnesium reacts with Xylidyl Blue I to produce a Magnesium-xylidyl blue complex which is red in color at the alkaline pH of the reagent. The disappearance of the near-infrared absorbing blue color is proportional to the amount of magnesium present in the serum.
Xylidyl Blue I + Mg+2 -> Xylidyl Blue-Mg+2 complex
(blue) (red)
The disappearance of the initial blue color as the xylidyl-Mg complex is formed can be measured between 630 nm and 670 nm and is proportional to the magnesium concentration. Calcium is prevented from forming a complex with the xylidyl blue by the inclusion of EGTA in the reaction mixture.
Analytical Range
Most applications of this procedure have been found to be linear to 2.5 mmol/L (5.0 mEq/L) magnesium.
Expected Values
The normal range for magnesium is reported to be 0.7 - 1.0 mmol/L (1.4-2.0 mEq/L)
Expected Results
Decreased levels of serum magnesium are seen in a variety of pathologic conditions. The most common reason for lowered levels in otherwise normal patients is alcoholism. Causes of hypomagnesemia are classified below.
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- Gastrointestinal and nutritional causes
- Prolonged parental fluid administration without magnesium
- Prolonged severe diarrhea, e.g. ulcerative colitis, regional enteritis, and chronic laxative abuse
- Intestinal malabsorption
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- Idiopathic steatorrhea
- Tropical sprue
- Short-bowel syndrome from any cause
- Alcoholism
- Acute and recurrent pancreatitis
- Starvation with attendant metabolic acidosis
- Diabetic ketoacidosis
- Protein-calorie malnutrition including kwashiorkor
- Renal causes
- Prolonged use of diuretics
- Renal disease
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- Renal tubular acidosis
- Recovery from acute tubular necrosis
- Chronic glomerulonephritis and pyelonephritis
- Familial magnesium wastage
- Gentamycin-induced renal injury
- Endocrine and metabolic causes
- Hyperthyroidism
- Hyperparathyroidism with osteitis fibrosa cystica
- Malacic bone disease with hypercalcemia
- Primary and secondary aldosteronism
- Excessive lactation
- Congenital hypoparathyroidism
- Infant born of mother with hyperparathyroidism
- Neonatal and childhood causes
- Infantile convulsions
- Newborns of diabetic mothers
- Genetic (male) hypomagnesemia
- Exchange transfusions
Hypermagnesemia and intoxication occur mainly in patients with serious renal insufficiency and in eclampsia when large doses of magnesium salts are administered. The administration of magnesium-containing antacids in patients with renal failure is an important cause of magnesium intoxication.
Product Packaging and Storage
Cat No. |
Product Name |
Packaging |
Packaging Volume (mL) |
Storage |
IR170-X |
Magnesium |
2x250 mL |
500 |
20-25° C |
IR170 |
Magnesium |
6x250 mL |
1,500 |
20-25° C |
IR170-L |
Magnesium |
6x1000 mL |
6,000 |
20-25° C |
IR170-911 |
Magnesium |
4x20 mL |
80 |
20-25° C |
IR170-WK |
Magnesium |
2x55mL |
110 |
20-25° C |