Liver stiffness assessment through 2D shear wave elastography (2D SWE) could be valuable for liver disease screening in patients with cystic fibrosis (CF), according to a new study published in the Journal of Cystic Fibrosis. Evidence shows that increased liver stiffness is directly correlated with low vitamin D levels and abnormalities in glucose metabolism.

Although liver disease is a common complication in young patients with CF, with up to 10% developing severe symptoms and cirrhosis, the early stages are usually asymptomatic. Thus, this situation creates the need for regular liver disease screening in patients with CF.

Currently, there is no gold standard for liver disease screening in patients with CF; due to the uneven distribution of lesions in these patients, liver biopsies can be unreliable. The most commonly used method is a combination of liver ultrasound with biochemical workup. Therefore, the interest in new diagnostic methods for liver disease in patients with CF is high.

Elastography is a diagnostic tool that measures tissue stiffness; several studies have tested transient elastography and demonstrated a low sensitivity. However, the evidence on 2D SWE remains scarce.

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The authors performed a retrospective cohort study involving 51 children with CF subjected to yearly liver disease screening with liver ultrasonography, biochemical workup, and 2D SWE. The results of lung function tests, vitamin D measurements, and glucose tolerance testing were also obtained. 

The results showed that almost 40% of patients had some degree of liver abnormalities noted on ultrasound, ranging from fibrosis to mere enlargement. The 4 patients with liver biopsy-confirmed cirrhosis had a significantly higher liver stiffness measured by 2D SWE than the rest of the population (15 kPa compared to a mean value of 5 kPa). Patients with fibrosis also had mildly elevated liver stiffness compared to those without fibrosis.

The authors noted a statistically significant inverse correlation between vitamin D levels and liver stiffness. Furthermore, patients with abnormalities in glucose metabolism tended to have higher liver stiffness.

“Increased liver stiffness is associated with lower vitamin D levels, inferior lung function and abnormal glucose tolerance,” they wrote.

They believe that due to its noninvasive nature, 2D SWE could be a great complement to an ultrasonographic evaluation in patients with CF and a valuable individual tool in the surveillance of disease progression.

Reference

Elidottir H, Hansen CR, Diemer S, Eklund EA. 2D shear wave elastography, a promising screening tool for cystic fibrosis liver disease, shows a correlation between vitamin D and liver stiffness. J Cyst Fibros. Published online July 3, 2022. doi:10.1016/j.jcf.2022.06.009