Metformin Overdose Symptoms

Introduction to Metformin Overdose

Metformin is a widely prescribed medication for managing type II diabetes mellitus. However, an overdose of metformin can lead to severe and potentially life-threatening symptoms. This article synthesizes findings from multiple case reports and studies to outline the primary symptoms and complications associated with metformin overdose.

Metabolic Acidosis and Hyperlactatemia

Severe Metabolic Acidosis

One of the most critical symptoms of metformin overdose is severe metabolic acidosis, often accompanied by hyperlactatemia. This condition, known as metformin-associated lactic acidosis (MALA), is characterized by a significant drop in blood pH and elevated lactate levels. Patients often present with symptoms such as nausea, vomiting, and general weakness . In severe cases, the pH can drop below 7.0, necessitating urgent medical interventions like hemodialysis to correct the acidosis .

Hyperlactatemia

Hyperlactatemia, or elevated lactate levels in the blood, is a hallmark of metformin toxicity. This condition can exacerbate metabolic acidosis and lead to further complications. In one case, a patient had lactate levels as high as 33 mmol/L, which required immediate hemodialysis for stabilization.

Respiratory and Cardiovascular Complications

Acute Respiratory Distress Syndrome (ARDS)

Metformin overdose can lead to hypoxaemic respiratory failure secondary to ARDS. This condition results in severe breathing difficulties and requires mechanical ventilation for management. In one reported case, a patient developed ARDS and required extracorporeal membrane oxygenation (ECMO) to stabilize her condition.

Hemodynamic Instability

Patients with metformin overdose often experience hemodynamic instability, including hypotension and shock. This can be resistant to standard vasopressor support, necessitating advanced interventions like ECMO or continuous renal replacement therapy (CRRT) .

Neurological Symptoms

Altered Mental Status

Altered mental status is a common symptom in metformin overdose cases. Patients may present with obtunded mental status, lethargy, and unresponsiveness. These symptoms are often a result of severe metabolic acidosis and require immediate medical attention .

Hypoglycemia

Hypoglycemia, or low blood sugar levels, is another critical symptom. It can lead to asphyxial syndrome, cyanosis of the extremities, and even death if not promptly treated. In one case, a patient was found dead with signs of hypoglycemia and multi-visceral congestion.

Renal and Hepatic Complications

Kidney Failure

Acute kidney failure is a severe complication of metformin overdose. It often necessitates renal replacement therapies like hemodialysis or CRRT to manage the condition and remove the toxin from the body .

Hepatotoxicity

Although rare, metformin-induced hepatotoxicity can occur, leading to liver damage. Symptoms include jaundice, fatigue, and elevated liver enzymes. Discontinuation of metformin usually results in the normalization of liver function over time.

Conclusion

Metformin overdose can lead to a range of severe symptoms, including metabolic acidosis, hyperlactatemia, respiratory and cardiovascular complications, altered mental status, hypoglycemia, kidney failure, and hepatotoxicity. Prompt medical intervention, often involving hemodialysis or other advanced therapies, is crucial for managing these symptoms and improving patient outcomes. Understanding these symptoms can aid in the timely diagnosis and treatment of metformin toxicity.

Metformin overdose symptoms

Summary

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