From the Guidelines
An anion gap of 20 in a 20-month-old child is elevated and requires prompt medical evaluation, as it suggests metabolic acidosis which can indicate serious underlying conditions, and the child should be taken to a pediatrician or emergency department for immediate assessment. The normal range for anion gap is typically 8-16 mEq/L, and an elevated anion gap can be caused by various factors such as diabetic ketoacidosis, ingestion of toxins, severe dehydration, kidney dysfunction, or certain inborn errors of metabolism 1.
The healthcare provider should obtain a complete metabolic panel, urinalysis, and possibly blood gas analysis to determine the cause of the elevated anion gap. Parents should report any symptoms such as vomiting, unusual breathing patterns, lethargy, or confusion, as well as any possible ingestions or exposures. Treatment will depend on the underlying cause but may include IV fluids, electrolyte correction, and specific treatments for the identified condition.
According to a recent study published in Critical Care in 2023, the anion gap is a useful surrogate marker for glycolate and correlates linearly with glycolate and is associated with clinical outcomes 1. However, the anion gap may overestimate or underestimate the glycolate concentration in certain circumstances, such as concomitant acute kidney injury or ketoacidosis, and other acid-base parameters such as pH, HCO3–, and base excess should also be consulted 1.
In cases of suspected ethylene glycol poisoning, the anion gap can be used to guide the decision for extracorporeal treatment, with an anion gap of 24-28 mmol/L suggesting the need for treatment and an anion gap greater than 28 mmol/L indicating a high risk of mortality 1. However, the anion gap should not be used indiscriminately, and other clinical manifestations such as respiratory failure and pulmonary edema should also be considered.
Overall, an elevated anion gap in a 20-month-old child requires prompt medical attention, and a thorough evaluation should be performed to determine the underlying cause and guide treatment. The most recent and highest quality study on this topic is from 2023, which provides guidance on the use of anion gap in the diagnosis and treatment of ethylene glycol poisoning 1.
From the Research
Anion Gap Interpretation
The anion gap is a useful calculation in diagnosing acid-base disorders, particularly in pediatric patients 2.
Normal Anion Gap Values
A study published in 2020 derived a new reference interval for anion gap values, which is 7 to 18 mmol/L with a median of 13 mmol/L in healthy adults 3.
Anion Gap of 20 in a 20-month-old
Given the anion gap of 20 in a 20-month-old, this value is slightly above the upper limit of the reference interval. However, it is essential to consider that the reference interval may vary depending on the population and laboratory methods used 3, 4.
Clinical Significance
An elevated anion gap can indicate metabolic acidosis, but it can also reflect laboratory error, metabolic alkalosis, hyperphosphatemia, or paraproteinemia 4. In pediatric patients, metabolic acidosis can occur due to various causes, including hypoxia, sepsis, gastroenteritis, and hypovolaemia 2.
Diagnostic Approach
To determine the cause of the elevated anion gap, it is crucial to consider the patient's clinical presentation, laboratory results, and medical history. The anion gap should be used in conjunction with other diagnostic tools, such as plasma osmolality and osmolal gap calculations, to guide clinical decision-making 5.
Key Points to Consider
- The anion gap is a useful calculation in diagnosing acid-base disorders.
- The reference interval for anion gap values may vary depending on the population and laboratory methods used.
- An elevated anion gap can indicate metabolic acidosis, but it can also reflect other conditions.
- A comprehensive diagnostic approach is necessary to determine the cause of the elevated anion gap.