Thyroid hormone metabolism in patients with liver cirrhosis, as judged by urinary excretion of triiodothyronine

Joint Analysis of Genetic Correlation, Mendelian Randomization and Colocalization Highlights the Bi-Directional Causal Association Between Hypothyroidism and Primary Biliary Cirrhosis

Background: Hypothyroidism and primary biliary cirrhosis (PBC) are often co-existed in observational epidemiological studies. However, the causal relationship between them remains unclear.

Methods: Genetic correlation, Mendelian randomization (MR) and colocalization analysis were combined to assess the potential causal association between hypothyroidism and PBC by using summary statistics from large-scale genome-wide association studies. Various sensitivity analyses had been conducted to assess the robustness and the consistency of the findings.

Results: The linkage disequilibrium score regression demonstrated significant evidence of shared genetic architecture between hypothyroidism and PBC, with the genetic correlation estimated to be 0.117 (p = 0.006). The OR of hypothyroidism on PBC was 1.223 (95% CI, 1.072–1.396; p = 2.76 × 10⁻³) in MR analysis with inverse variance weighted (IVW) method. More importantly, the results from other 7MR methods with different model assumptions, were almost identical with that of IVW, suggesting the findings were robust and convincing. On the other hand, PBC was also causally associated with hypothyroidism (OR, 1.049; 95% CI, 1.010–1.089; p = 0.012), and, again, similar results can also be obtained from other MR methods. Various sensitivity analyses regarding the outlier detection and leave-one-out analysis were also performed. Besides, colocalization analysis suggested that there existed shared causal variants between hypothyroidism and PBC, further highlighting the robustness of the results.

Conclusion: Our results suggest evidence for the bi-directional causal association between hypothyroidism and PBC, which may provide insights into the etiology of hypothyroidism and PBC as well as inform prevention and intervention strategies directed toward both diseases.

Gastric estrogen increases pituitary estrogen receptor α and prolactin mRNAs during the different pathological conditions of the liver

Mammalian liver is an estrogen-responsive tissue mediated by hepatic estrogen receptors. Although Ueyama et al. (Endocrinology 143:3162-3170, 2002) have reported the presence of aromatase and active production of gastric 17β-estradiol in parietal cells, there are a few studies on gastric 17β-estradiol exploring the relationship between gastro-hepato function and the gastro-pituitary-gonadal axis. The alteration of gastric 17β-estradiol flow into the systemic circulation by portal vein ligation (PVL) or partial hepatectomy (PH), and the effect of gastric 17β-estradiol on the pituitary function was investigated. In the PVL rats, arterial 17β-estradiol increased 9.5 times that of controls on day 3, and gradually decreased near to control levels in the portal vein by 4 weeks, which was still 5 times higher than those in the arteries of the control rats. In the PH rats, arterial 17β-estradiol increased 2 times that of controls on day 3, and gradually decreased to the control levels. Regeneration and growth of the liver remnants were observed about 2 weeks after PH. In the PVL and PH animals, pituitary ERα and prolactin mRNAs levels increased, positively correlating with an increase of arterial 17β-estradiol levels. Both reduced LHβ mRNA. It is apparent that hepatic dysfunction causes changes in gastric 17β-estradiol levels in the systemic circulation; and that elevated gastric 17β-estradiol affects pituitary function(s). This data suggest that gastric 17β-estradiol has a pivotal role in the regulation of the gastro-hepato-pituitary axis.

[Thyroid hormones in women with liver cirrhosis]

Basal thyroid hormone levels were measured in 68 women with liver cirrhosis (LC) of different etiology (alcoholic n = 34, posthepatitic B n = 9, PBC n = 5, cryptogenetic n = 18, M. Wilson n = 2). In addition the rise of TSH after 400 micrograms TRH was measured in 23 women with LC and compared with the data obtained from 17 women of a control group. There was no difference of the median T4-concentrations (LC 8.0 micrograms/dl versus 7.2 micrograms/dl) but a significant correlation of T4 to the grade of decompensation of LC. In contrast of T4 there was a marked decrease of T3 in LC-patients (109 ng/dl versus 143 ng/dl) and a rise of reverse T3 (0.21 ng/ml versus 0.13 ng/ml). The decrease of T3 and rise of reverse T3 equally correlated to the severeness of LC. TBG concentrations fell according to the grade of decompensation of LC and T4/TBG-quotient exhibited no difference to the control data (0.51 both). Though basal thyroid hormones and TSH show euthyroidism the significant augmented TSH release after TRH (delta-TSH 7.0 versus 3.2 microU/ml) indicate a status of latent hypothyroidism. In alcoholic cirrhosis the degree of TSH release was much higher than in non alcoholic cirrhosis. Estradiol and estrone levels correlated significantly negatively to T4, T3, estrone negatively to TBG and positively to reverse T3 but not to TSH and TSH release. Otherwise TSH release correlated positively to estradiol. The thyroid status in women with liver cirrhosis does not differ from the thyroid hormone profile found in men with cirrhosis.