About one of every five patients with NAFLD had hypothyroidism. Although being female increased the odds, any history of alcohol consumption, no matter how modest, reduced the association between NAFLD and hypothyroidism.

Mangesh Pagadala, MD, of the Cleveland Clinic, said in an interview at the American College of Gastroenterology meeting, "I think patients with hypothyroidism have to be considered as a risk group that might need to be screened for fatty liver disease, especially nonalcoholic steatohepatitis.... This might help decrease the burden of cirrhosis by identifying and treating patients earlier."

The findings add support to suspicions about an association between NAFLD and hypothyroidism. For example, a commentary on a study of fatigue in NAFLD included a suggestion that hypothyroidism might be the culprit behind fatigue (Gut 2009; 58: 149-50).

Pagadala noted that a rationale for the association can be found in the observation that elements of the metabolic syndrome are common to both hypothyroidism and NAFLD.

In an effort to confirm and characterize the association, investigators reviewed data on 266 patients with biopsy-proven NAFLD seen at the Cleveland Clinic between 2007 and 2009.

They were matched for age, sex, race, and body mass index with 479 patients who had normal liver enzyme and alkaline phosphatase levels, intact synthetic liver function, and no history of liver disease.

Hypothyroidism was defined as a clinical diagnosis of the condition or current treatment for hypothyroidism.

The NAFLD cohort and control group were similar except for a higher prevalence of hypertension, diabetes, and hyperlipidemia in the patients with NAFLD (P<0.001).

Pagadala reported that 19.2% of the NAFLD patients had hypothyroidism compared with 10.4% of the control group (P=0.003).

The difference translated into an odds ratio of 1.9 (95% CI 1.2 to 2.9), which remained statistically significant after adjustment for diabetes, hypertension, and hyperlipidemia (P=0.004). Hypothyroidism prevalence did not differ between patients with simple steatosis and nonalcoholic steatohepatitis.

In a multivariable analysis, women with NAFLD had an odds ratio of 5.3 for hypothyroidism (P<0.0001). Any history of alcohol intake (compared with total abstinence) reduced the risk of hypothyroidism by 70% (OR 0.3, P=0.001). Hypertension, diabetes, liver enzyme levels, and BMI did not have a significant impact on the association between NAFLD and hypothyroidism.

The results provide a starting point for investigating the association between NAFLD and hypothyroidism, said Pagadala. Other studies are needed to corroborate the findings, the associations described, and their pathogenesis.

Practice Pearl:   Explain to patients that this study showed that people with nonalcoholic fatty liver disease are twice as likely to have hypothyroidism as people who do not have the liver condition.

Pagadala M, et al "Assessment of the prevalence of hypothyroidism in nonalcoholic fatty liver disease" ACG 2009; Abstract P177.