What laboratory result is commonly associated with cystic fibrosis?

The laboratory result commonly associated with cystic fibrosis is a sweat chloride concentration greater than 60 mmol/L. This result is significant because cystic fibrosis is a genetic disorder that affects the transport of chloride and sodium ions across epithelial cells, leading to the production of sweat that is abnormally salty.

In individuals with cystic fibrosis, the dysfunctional CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) protein results in increased chloride levels in sweat. Therefore, when sweat is analyzed, a concentration of chloride greater than 60 mmol/L is considered diagnostic for cystic fibrosis in most cases. This test is a crucial part of the diagnostic process for the condition.

While elevated serum sodium and chloride could occur in cystic fibrosis due to the underlying dysfunction in ion transport, the sweat test remains the gold standard for diagnosis. Similarly, elevated fecal trypsin activity is not characteristic of cystic fibrosis but rather suggests pancreatic sufficiency, which is less common in severe cases of the disease. Low glucose levels are unrelated to the definitive diagnosis of cystic fibrosis and are not a characteristic feature of the disorder. Thus, the definitive nature of the sweat chloride test makes it the correct answer for identifying cystic fibrosis.