Does a normal lactic acid level rule out ischemic colitis?

From the Guidelines

No, a normal lactic acid level does not rule out ischemic colitis. According to the most recent guidelines from the World Society of Emergency Surgery, published in 2022 1, there are no laboratory parameters that are sufficiently accurate to conclusively identify the presence or absence of ischemic or necrotic bowel. While elevated l-lactate, leukocytosis, and D-dimer may assist in the diagnosis, they are not definitive. The guidelines emphasize that laboratory results are not reliable for differentiating early ischemia versus irreversible bowel injury based on lactate levels alone, unless accompanied by other clinical evidence.

Key Points to Consider

• Elevated serum lactate levels > 2 mmol/l are associated with irreversible intestinal ischemia, but normal levels do not rule out the condition 1.
• More than 90% of patients with acute mesenteric ischemia will have an abnormally elevated leukocyte count, and 88% will have metabolic acidosis with elevated lactate levels 1.
• D-dimer has been reported to be an independent risk factor for intestinal ischemia, but its specificity and sensitivity are limited 1.
• Computed tomography angiography (CTA) is the diagnostic study of choice for suspected acute mesenteric ischemia, and should be performed as soon as possible 1.

Clinical Implications

• Clinicians should maintain a high index of suspicion for ischemic colitis in at-risk patients, even when lactic acid levels are normal.
• Diagnosis of ischemic colitis should rely on a combination of clinical presentation, imaging studies, and ultimately colonoscopy with biopsy.
• Other laboratory markers like leukocytosis or elevated inflammatory markers may be present, but are also nonspecific.
• The presence of lactic acidosis in combination with abdominal pain should lead to consideration of early CTA, especially in patients who may not otherwise appear clinically ill 1.

From the Research

Ischemic Colitis Diagnosis

• Ischemic colitis is a common cause of hospital admissions, often confused with other conditions such as infectious diarrhea or Clostridium difficile colitis 2.
• The diagnosis of ischemic colitis can be challenging and requires proficient knowledge of the disease 2.
• Colonoscopy is the procedure of choice for diagnosis, and computed tomography may have suggestive findings 3.

Lactic Acid Levels

• Elevated lactic acid levels can be an indicator of ischemic colitis, as seen in a case report of stercoral colitis complicated with ischemic colitis 4.
• However, a normal lactic acid level does not necessarily rule out ischemic colitis, as the condition can present with a range of symptoms and laboratory findings 3, 5.
• Lactic acidosis is a significant finding in some cases of ischemic colitis, particularly those with severe disease or complications such as stercoral colitis 4.

Diagnostic Considerations

• Ischemic colitis can be classified as non-gangrenous or gangrenous, with non-gangrenous cases accounting for 80-85% of all cases 6.
• The diagnosis of ischemic colitis requires a combination of clinical evaluation, laboratory tests, and imaging studies, including colonoscopy and computed tomography 2, 3, 6.
• A high index of suspicion is necessary to diagnose ischemic colitis, particularly in patients with risk factors such as advanced age, cardiovascular disease, or medications that can cause vasoconstriction 2, 5.