Commentary: how long does one need to fast before a Fibroscan examination?

Authors

  • K. L. Y. Lam,

    Corresponding author
    1. Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
    2. Institute of Digestive Disease and State Key Laboratory of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
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  • A. J. Hui,

    1. Institute of Digestive Disease and State Key Laboratory of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
    2. Department of Medicine, Alice Ho Miu Ling Nethersole Hospital, Hong Kong, China
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  • H. L. Y. Chan

    1. Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China
    2. Institute of Digestive Disease and State Key Laboratory of Digestive Disease, The Chinese University of Hong Kong, Hong Kong, China
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Liver stiffness measurement (LSM) is a well-validated non-invasive method to assess liver fibrosis in various liver diseases.[1] In chronic hepatitis B, aminotransferase has been shown to be the major factor affecting LSM.[2, 3] Fibroscan has the beauty of being simple and fast; it can be done in an out-patient setting for a large volume of patients throughout the day.

Recent data have shown that food intake might affect the LSM. One therefore needs to know how long a patient has to fast before the procedure, particularly when Fibroscan is performed in the middle of the day instead of in the early morning. Three studies showed that food intake increased LSM in chronic hepatitis C and cirrhotic patients and LSM returned to baseline after 3 h.[4-6]

Lemoine and colleagues demonstrated that food intake after a standardised meal increased liver stiffness in patients with chronic hepatitis B and healthy controls.[7] There was 0.9 kPa increased in LSM at 120 min, which might lead to overestimation of liver fibrosis. The reliability of LSM, as measured by the ratio of interquartile range to LSM, was also hampered after a meal – an intriguing finding that requires further validation. In the literature, obesity is the key factor that increases the failure rate and unreliable results of Fibroscan.[8]

In our hospital, we have studied 69 chronic hepatitis B patients with undetectable HBV DNA and normal aminotransferases under anti-viral treatment. Each patient had fasting and 4 h post meal, LSM was measured at week 0 and 2, and the results were combined for analysis. The mean LSM at fasting was 6.3 (2.3–21.3) kPa and 4 h post meal was 6.8 (2.1–35.3) kPa (difference 0.5 kPa; P = 0.05). Fibroscan still had a borderline tendency to overestimate the stage of fibrosis after fasting for 4 h (Table 1). In this study, the reliability of LSM was not affected by a meal.

Table 1. Differences in liver stiffness measurement at fasting and 4 h after meal in 69 patients with examinations at week 0 and week 2
 FastingTotal
No fibrosisFibrosisCirrhosis
  1. No fibrosis: Liver stiffness score <7.0k Pa; Fibrosis: Liver stiffness score 7.0–12.0k Pa; Cirrhosis: Liver stiffness score >12 kPa.

4 h post meal
No fibrosis92 (68%)6 (4%)0 (0%)98 (71%)
Fibrosis13 (9%)17 (12%)1 (1%)31 (22%)
Cirrhosis0 (0%)4 (3%)5 (3%)9 (6%)
Total105 (77%)27 (19%)6 (4%)138 (100%)

Putting all the evidence together, to avoid overestimation of liver fibrosis by Fibroscan, one should probably advise a patient to fast for at least 4 h before the procedure.

Acknowledgement

Declaration of personal interests: HLY Chan is an advisor for Bristol Myers Squibb, Gilead, Novartis Pharmaceutical, Merck and Roche; has received honorarium for lectures from Bristol Myers Squibb, Gilead, Novartis Pharmaceutical, Merck, Roche, Echosens and Glaxo-Smith-Kline; and has received an unrestricted grant for hepatitis B virus research from Roche.

Declaration of funding interests: None.

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