From the Guidelines
The most appropriate immediate treatment for this patient is intravenous calcium gluconate (option A). This patient is experiencing symptomatic hypermagnesemia due to ingestion of magnesium citrate in the setting of stage G4 chronic kidney disease. The clinical manifestations include hypotension, bradycardia, muscle weakness, and absent reflexes, which are classic signs of magnesium toxicity, as described in the 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1. The laboratory findings confirm severe hypermagnesemia with a magnesium level of 6.8 mg/dL. Key points to consider in the management of this patient include:
- The need for immediate intervention to counteract the effects of hypermagnesemia
- The role of calcium gluconate as a physiological antagonist to magnesium at the neuromuscular junction and cardiac tissue, as noted in the guidelines 1
- The importance of addressing the underlying cause of hypermagnesemia, in this case, the ingestion of magnesium citrate in a patient with impaired renal function Calcium gluconate acts as a physiological antagonist to magnesium at the neuromuscular junction and cardiac tissue, rapidly counteracting the neuromuscular and cardiovascular effects of hypermagnesemia, as outlined in the guidelines 1. This treatment will help stabilize the patient while additional measures to remove excess magnesium are implemented. Other options, such as furosemide, sodium bicarbonate, and patiromer, are not the most appropriate initial treatments for acute hypermagnesemia management in this critically ill patient. After calcium administration, hemodialysis may be necessary for definitive treatment given the patient's kidney dysfunction and inability to excrete the excess magnesium.
From the FDA Drug Label
2 DOSAGE & ADMINISTRATION
2.1 Important Administration Instructions Calcium Gluconate Injection contains 100 mg of calcium gluconate per mL which contains 9.3 mg (i.e., 0.465 mEq) of elemental calcium.
10 OVERDOSAGE
Overdosage of Calcium Gluconate Injection may result in hypercalcemia. Symptoms of hypercalcemia typically develop when the total serum calcium concentration is ≥12 mg/dL.
The patient has hypercalcemia is not present, but rather hypermagnesemia. However, the patient's symptoms such as generalized weakness, absent reflexes, and low blood pressure can be associated with hypermagnesemia. The most appropriate immediate treatment for hypermagnesemia is intravenous calcium gluconate as a calcium salt can help antagonize the effects of magnesium at the neuromuscular junction. Therefore, the correct answer is A Intravenous calcium gluconate 2 2.
From the Research
Immediate Treatment for Hypermagnesemia
The patient presents with generalized weakness, absent reflexes, and a high magnesium level of 6.8 mg/dL, indicating hypermagnesemia. The most appropriate immediate treatment for hypermagnesemia is:
- Administration of intravenous calcium gluconate to counteract the effects of magnesium on the nervous system and cardiovascular function 3, 4
Rationale for Treatment Choice
The use of intravenous calcium gluconate is supported by studies that demonstrate its effectiveness in treating hypermagnesemia and hypocalcemia:
- A case report of severe hypermagnesemia with normal renal function showed improvement with symptomatic treatment, including administration of calcium preparation 3
- A review of hypermagnesemia in clinical practice highlights the importance of prompt identification and management to prevent complications, and recommends discontinuing magnesium-containing therapies and considering intravenous fluid therapy or dialysis in severe cases 4
- Studies on the treatment of hypocalcemia also support the use of intravenous calcium gluconate, demonstrating its effectiveness in increasing serum ionized calcium concentrations and normalizing calcium levels in critically ill patients 5, 6
Other Treatment Options
Other treatment options, such as intravenous furosemide, intravenous sodium bicarbonate, and oral patiromer, may be considered in certain cases, but are not the most appropriate immediate treatment for this patient:
- Intravenous furosemide may be used to enhance magnesium excretion, but its use is not supported by the provided evidence as the primary treatment for hypermagnesemia 3, 4
- Intravenous sodium bicarbonate is not typically used to treat hypermagnesemia, and its use is not supported by the provided evidence
- Oral patiromer is a potassium-binding medication that may be used to treat hyperkalemia, but its use is not relevant to the treatment of hypermagnesemia in this case