Can Hashimoto’s Disease Cause Liver Problems?

Hashimoto’s thyroiditis can affect the liver through several distinct pathways, ranging from fatty liver disease driven by thyroid hormone deficiency to autoimmune conditions that attack the liver directly. The connection is not a single, neat mechanism but a web of metabolic, immune, and hormonal links that researchers have been mapping with increasing precision. Some of these liver effects are reversible once thyroid function is restored; others require their own treatment.

Fatty Liver Disease Is the Most Common Link

The liver depends on thyroid hormones to manage fat. When Hashimoto’s causes hypothyroidism, the liver’s ability to break down and export lipids slows, and fat begins to accumulate in liver cells. This condition, now called metabolic dysfunction-associated steatotic liver disease (previously known as non-alcoholic fatty liver disease or NAFLD), is the most frequently studied liver complication tied to hypothyroidism. Deficiency of thyroid hormones has been linked to abnormal lipid metabolism, and NAFLD remains an important and well-documented association with the hypothyroid state.¹

A Mendelian randomization study looked specifically at whether Hashimoto’s thyroiditis itself, rather than hypothyroidism in general, drives fatty liver risk. Using genetic data, the researchers found that Hashimoto’s modestly increased the odds of developing NAFLD, with no evidence that the relationship works in the other direction. In other words, Hashimoto’s appears to promote fatty liver, but fatty liver does not appear to cause Hashimoto’s.²

The encouraging part: liver dysfunction tied to hypothyroidism is usually reversible when thyroid hormone levels are brought back to normal with medication like levothyroxine.¹ That said, if fatty liver has progressed to significant scarring before treatment begins, the damage may not fully resolve, which is one reason endocrinologists emphasize keeping thyroid levels well-controlled.

Thyroid Antibodies Can Affect the Liver Even When Hormone Levels Look Normal

One of the more surprising findings in recent research is that the antibodies characteristic of Hashimoto’s, specifically thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb), are linked to fatty liver even in people whose thyroid-stimulating hormone (TSH) levels are within the normal range. A large cross-sectional study found that the presence of these antibodies was positively associated with NAFLD in both men and women, and that people who tested positive for both antibodies and showed ultrasound evidence of thyroid abnormality had a further elevated risk.³

A separate study looking at patients with type 2 diabetes and fatty liver found that rising TPOAb levels correlated with the severity of fatty liver on imaging.⁴ This matters because many people with Hashimoto’s spend years in a “euthyroid” phase where their hormone numbers look fine on standard blood work but their antibody levels are elevated. The implication is that the autoimmune process itself, not just the resulting hormone shortage, may contribute to liver fat accumulation.

Researchers exploring the shared biology between Hashimoto’s and NAFLD at the cellular level have identified an increase in a specific type of immune cell, CD4+ central memory T cells, in people with both conditions. They also found a gene called MAGI3 that appears to be causally linked to both diseases, suggesting a shared genetic susceptibility rather than a simple one-causes-the-other relationship.⁵

Autoimmune Hepatitis Overlaps With Hashimoto’s More Than Expected

Hashimoto’s is an autoimmune disease, and autoimmune diseases tend to travel together. Autoimmune hepatitis (AIH), a condition in which the immune system attacks liver cells, is one of the liver-specific autoimmune diseases that clusters with Hashimoto’s. A bidirectional Mendelian randomization study found that Hashimoto’s was associated with a roughly 40% increase in the odds of developing autoimmune hepatitis.⁶ Autoimmune hepatitis typically shows up as persistently elevated liver enzymes, fatigue, and sometimes jaundice. It can progress to cirrhosis if untreated, but it responds well to immunosuppressive therapy in most cases.

Case reports have documented patients whose Hashimoto’s and autoimmune hepatitis were diagnosed simultaneously, with liver biopsy confirming the hepatitis diagnosis.⁷ These are not coincidences. Autoimmune thyroid disease is the most frequently overlapping extrahepatic autoimmune condition seen alongside autoimmune liver diseases.⁸

The practical takeaway for someone with Hashimoto’s: if your liver enzymes are persistently elevated and there is no obvious explanation like alcohol use or medication side effects, autoimmune hepatitis is worth investigating. A standard metabolic panel alone will not distinguish it from other causes; your doctor may need to check for specific autoantibodies (anti-smooth muscle antibodies, anti-nuclear antibodies) and potentially refer you for a liver biopsy.

Primary Biliary Cholangitis Is Another Autoimmune Overlap

Primary biliary cholangitis (PBC) is a chronic liver disease in which the immune system slowly destroys the small bile ducts inside the liver. It predominantly affects women, as does Hashimoto’s, and the two conditions co-occur at a rate well above chance. In one study of patients with PBC, about 20% had Hashimoto’s thyroiditis.⁹ PBC tends to cause fatigue, itching, and elevated alkaline phosphatase on blood work rather than the dramatic transaminase spikes seen in autoimmune hepatitis.

Some patients develop what clinicians call multiple autoimmune syndrome, where three or more autoimmune conditions exist together. A case report described a 78-year-old woman with primary biliary cholangitis, inflammatory myopathy, and Hashimoto’s disease simultaneously, treated with corticosteroids and immunosuppressive medication.¹⁰ Cases like this illustrate an important principle: when one autoimmune diagnosis is on the table, clinicians should keep a low threshold for testing for others, including liver-specific ones.

Gallstones and Sluggish Bile Flow

Beyond the liver tissue itself, hypothyroidism from Hashimoto’s can affect the biliary system, the network of ducts that carries bile from the liver to the intestine. Hypothyroidism appears to reduce bile secretion and impair the relaxation of the sphincter of Oddi, the muscular valve that controls bile flow into the small intestine. When bile sits stagnant, it can become supersaturated with cholesterol, creating conditions ripe for gallstone formation.¹¹

Animal research supports this connection. In a study of mice, cholesterol crystal formation occurred in 83% of hypothyroid animals compared to only 33% of mice with normal thyroid function. The researchers found that hypothyroidism promoted gallstone formation specifically by upregulating cholesterol production in the liver.¹² While mouse biology does not translate directly to humans, the pattern matches the clinical observation that hypothyroid patients have higher rates of gallstones. If you have Hashimoto’s with poorly controlled hypothyroidism and develop right-upper-quadrant abdominal pain, gallbladder disease should be on the differential.

Bilirubin Clearance Can Be Impaired

Thyroid hormones also influence how efficiently the liver processes bilirubin, the yellow pigment produced when red blood cells break down. This is most dramatically visible in newborns with congenital hypothyroidism, where prolonged jaundice is the most common clinical finding. A study of neonates found that TSH levels positively correlated with both total and indirect bilirubin concentrations in hypothyroid infants.¹³ In adults with Hashimoto’s, this effect is subtler, but mildly elevated bilirubin can sometimes show up on routine blood work in the setting of undertreated hypothyroidism and should not automatically be attributed to liver disease.

Hypothyroidism Changes How the Liver Handles Medications

The liver is responsible for metabolizing most drugs, and this process depends on a family of enzymes called cytochrome P450. Thyroid status directly affects the expression of these enzymes. Research in hypothyroid mice showed that expression of key cytochrome P450 enzymes was suppressed in the hypothyroid state, while a compensatory enzyme was upregulated through a different regulatory pathway. When hypothyroid mice were given the drug carbamazepine, their ability to clear it was altered, and in some genetically susceptible animals, chronic treatment was lethal.¹⁴

The human relevance is this: if your Hashimoto’s is not well-controlled, your liver may process certain medications more slowly or differently than expected. This is especially relevant for drugs with narrow therapeutic windows, where small changes in blood levels can mean the difference between an effective dose and a toxic one. It is one more reason to keep your thyroid levels in a good range, and to mention your thyroid condition to any doctor prescribing new medications.

Pregnancy Adds a Specific Liver Risk

Intrahepatic cholestasis of pregnancy (ICP) is a liver condition that causes intense itching, usually in the third trimester, and carries risks for the baby including preterm birth. A large study of pregnant women in Shanghai found that those with clinical hypothyroidism had roughly three times the odds of developing ICP compared to women with normal thyroid function. When the hypothyroidism was accompanied by positive TPOAb, as it typically is in Hashimoto’s, the risk was even higher and ICP tended to develop earlier in pregnancy.¹⁵ For women with Hashimoto’s who are pregnant or planning pregnancy, this underscores the importance of thyroid monitoring and close attention to any unexplained itching, particularly in the second half of pregnancy.

How the Liver Normally Relies on Thyroid Hormone

To understand why Hashimoto’s has so many liver effects, it helps to know that the liver is not just a passive target of thyroid hormones. It is a major site where thyroid hormone is activated. The thyroid gland mostly secretes T4, a relatively inactive precursor. Enzymes in the liver and other tissues convert T4 into T3, the biologically active form that drives metabolism.¹⁶ This means the liver is both a consumer and a processor of thyroid hormones, creating a feedback loop where reduced thyroid output weakens liver function, which in turn impairs thyroid hormone activation.

Research on thyroid hormone receptor beta (THRB), the main thyroid hormone receptor in the liver, has shown that activating this receptor protects liver cells from fat-induced damage. In laboratory experiments, stimulating THRB with T3 or a synthetic agonist called resmetirom reversed the buildup of triglycerides and cholesterol in fat-loaded liver cells and even reduced cell death below baseline levels.¹⁷ This protective role explains why the liver is so vulnerable when thyroid hormone signaling falters.

What Resmetirom Reveals About the Thyroid-Liver Connection

The recent approval of resmetirom, the first drug specifically designed to treat fatty liver disease with fibrosis, is arguably the most concrete validation of the thyroid-liver link. Resmetirom is a liver-directed drug that selectively activates the thyroid hormone receptor beta. It does not affect the heart or bones the way full thyroid hormone does, so it can mimic the liver-protective effects of thyroid signaling without causing hyperthyroid side effects elsewhere.

In a phase 3 trial, resmetirom at the 100 mg dose reduced liver fat content by about 36 percentage points more than placebo, and both the 80 mg and 100 mg doses were superior to placebo for resolving the inflammatory component of fatty liver disease and improving fibrosis by at least one stage.¹⁸ A meta-analysis of resmetirom trials confirmed large reductions in liver fat and steatosis measures across multiple dosing studies.¹⁹

Resmetirom was developed for the general population with fatty liver disease, not specifically for people with Hashimoto’s. But its mechanism of action is essentially a pharmaceutical demonstration of what Hashimoto’s takes away: when the liver lacks adequate thyroid hormone signaling, fat accumulates and inflammation follows. Restoring that signal, whether through levothyroxine for hypothyroidism or through a targeted receptor agonist like resmetirom for fatty liver, reverses the damage. For people with Hashimoto’s, the lesson is that thyroid hormone replacement is not just about energy levels and metabolism in the abstract; it is directly protecting your liver.

Coexisting Conditions That Compound Liver Risk

Hashimoto’s rarely exists in isolation, and some of the conditions it frequently accompanies can independently affect the liver. Celiac disease, for instance, has a well-established association with Hashimoto’s, and untreated celiac disease can cause mildly elevated liver enzymes that resolve on a gluten-free diet. Case reports have documented patients with Hashimoto’s, celiac disease, and markers of autoimmune hepatitis all present simultaneously, along with fatty liver.²⁰ In such cases, teasing apart which condition is causing the liver abnormalities can be genuinely difficult, and treatment needs to address each component.

Type 2 diabetes is another common companion to Hashimoto’s, and it carries its own strong association with fatty liver disease. When both are present, the liver effects are likely additive. The study linking TPOAb levels to fatty liver severity was conducted specifically in patients who also had type 2 diabetes, suggesting that thyroid autoimmunity amplifies liver fat accumulation on top of whatever metabolic dysfunction the diabetes is already causing.⁴ If you have Hashimoto’s plus diabetes or insulin resistance, monitoring your liver health with periodic blood work and possibly imaging is worth discussing with your doctor.

Hypothyroidism-associated myopathy, a condition where muscle tissue breaks down due to low thyroid hormone, can also muddy the clinical picture. When muscle cells are damaged, they release enzymes that show up on the same liver function tests used to screen for liver disease. A doctor seeing elevated AST and ALT might initially assume a liver problem when the source is actually muscle. This is a recognized pitfall in hypothyroid patients, and checking a muscle-specific enzyme like creatine kinase can help sort out the origin.¹

1
PubMed Central. Co-Morbid Hypothyroidism and Liver Dysfunction: A Review
2
PubMed Central. Exploring the causal relationship between Hashimoto thyroiditis and metabolic-associated fatty liver disease: A Mendelian randomization study
3
PubMed. The association of non-alcoholic fatty liver disease with thyroid peroxidase and thyroglobulin antibody: A new insight from SPECT-China study
4
Diabetes, Metabolic Syndrome and Obesity. Elevated TPOAb is a Strong Predictor of Autoimmune Development in Patients of Type 2 Diabetes Mellitus and Non-Alcoholic Fatty Liver Disease
5
PubMed. Unraveling the connection between Hashimoto’s Thyroiditis and non-alcoholic fatty liver disease: exploring the role of CD4(+)central memory T cells through integrated genetic approaches
6
PubMed Central. Association between thyroid diseases and autoimmune hepatitis: A bidirectional Mendelian randomization study
7
Endocrinology and Metabolism. A Case of Hashimoto’s Thyroiditis Accompanied by Autoimmune Hepatitis Diagnosed with Liver Biopsy
8
PubMed Central. Autoimmune hepatitis-primary biliary cholangitis overlap syndrome complicated by various autoimmune diseases: A case report
9
Gut and Liver. Extrahepatic Manifestations of Primary Biliary Cholangitis
10
PubMed Central. Mixed Multiple Autoimmune Syndrome Type 3 With Coexistence of Primary Biliary Cholangitis, Inflammatory Myopathy, and Chronic Thyroiditis: A Case Report
11
PubMed Central. A Review of Synchronous Findings of Hypothyroidism and Cholelithiasis
12
PubMed Central. Thyroid dysfunction, either hyper or hypothyroidism, promotes gallstone formation by different mechanisms
13
PubMed Central. Comparative Analysis of Hyperbilirubinemia Between Congenital Hypothyroidism and Euthyroidism in Neonates in Rawalpindi, Pakistan
14
PubMed Central. Opposing regulation of cytochrome P450 expression by CAR and PXR in hypothyroid mice
15
PubMed Central. The impact of hypothyroidism on the risk of intrahepatic cholestasis of pregnancy: a large-scale study based on pregnant women with hypothyroidism in Shanghai, China
16
PubMed Central. Type 3 deiodinase and consumptive hypothyroidism: a common mechanism for a rare disease
17
Nature. Thyroid hormone receptor beta (THRB) dependent regulation of diurnal hepatic lipid metabolism in adult male mice
18
The New England Journal of Medicine. A Phase 3, Randomized, Controlled Trial of Resmetirom in NASH with Liver Fibrosis
19
PubMed. Role of Resmetirom, a Liver-Directed, Thyroid Hormone Receptor Beta-Selective Agonist, in Managing Nonalcoholic Steatohepatitis: A Systematic Review and Meta-Analysis
20
The American Journal of the Medical Sciences. Hyposplenism associated with celiac disease and Hashimoto’s autoimmune thyroiditis: A case-based review