Thyroid Hormone Receptor-β Agonists: Patient Counseling Scripts for Women With MASH

What Is Resmetirom and Why Does It Matter for Women?

Resmetirom is a first-in-class, liver-directed, selective thyroid hormone receptor-β (THR-β) agonist approved by the FDA in March 2024 for adults with noncirrhotic MASH and moderate-to-advanced liver fibrosis (stages F2 and F3). It is the first drug ever approved for MASH.

Why Women Are Not Just Small Men With Liver Disease

Sex differences in liver disease are real and under-discussed. Estrogen normally exerts a hepatoprotective effect by suppressing de novo lipogenesis and reducing hepatic inflammation. After menopause, estrogen withdrawal accelerates hepatic fat accumulation, so MASH prevalence in women rises sharply in the sixth decade of life. One longitudinal analysis found that postmenopausal women had significantly higher MASH activity scores than premenopausal peers matched for body mass index, suggesting hormonal status is an independent driver.

Women with PCOS are a particularly vulnerable group. Hyperandrogenism and insulin resistance together create exactly the metabolic environment in which hepatic triglyceride accumulates. Estimates from a 2023 meta-analysis suggest women with PCOS have a 2.5-fold elevated risk of non-alcoholic fatty liver disease compared with age-matched controls, a finding that carries forward into the MASH era.

How Resmetirom Works (In Plain Language for the Counseling Room)

The Thyroid-Liver Connection

Thyroid hormone activates two receptor subtypes: THR-α, which drives cardiac rate and bone turnover, and THR-β, which governs hepatic lipid metabolism, cholesterol synthesis, and bile acid regulation. The liver is naturally enriched in THR-β.

Resmetirom binds THR-β with about 28-fold selectivity over THR-α, so it mimics thyroid hormone's metabolic effects in the liver without meaningfully accelerating heart rate or causing bone loss. Phase 1 pharmacokinetic data confirm that hepatic uptake accounts for the drug's preferential liver distribution.

Why That Selectivity Matters for Women

Women already face higher rates of autoimmune thyroid disease (Hashimoto thyroiditis affects women approximately 7-10 times more often than men). Some women on treatment will have pre-existing hypothyroidism managed with levothyroxine. Resmetirom can reduce TSH levels by increasing negative feedback through hepatic THR-β signaling, which may require levothyroxine dose adjustment in women already on thyroid replacement. This interaction is discussed in depth in the counseling script below.

MAESTRO-NASH: The Trial Behind the Drug

The MAESTRO-NASH trial (N = 966, 52 weeks, double-blind placebo-controlled) enrolled adults with biopsy-confirmed MASH and fibrosis stages F1b, F2, or F3. Approximately 54% of participants were women.

Key results at 52 weeks:

| Outcome | Resmetirom 80 mg | Resmetirom 100 mg | Placebo | |---|---|---|---| | MASH resolution + ≥1 fibrosis stage improvement | 26% | 30% | 10% | | Fibrosis improvement ≥1 stage (no worsening of NASH) | 24% | 25% | 14% | | LDL-C reduction | ~16% | ~19% | minimal | | Triglyceride reduction | ~18% | ~22% | minimal |

MAESTRO-NASH also showed reductions in liver stiffness on MRE and in liver fat on MRI-PDFF within 24 weeks.

One honest caveat you must share with patients: the trial was 52 weeks. Long-term cardiovascular outcomes, survival benefit, and cirrhosis prevention data are not yet available. The FDA required a post-marketing outcomes trial as a condition of accelerated approval. This is real data that exists now; extrapolating a 20-year benefit is not.

Pregnancy, Lactation, and Contraception: What You Must Tell Every Woman

This section is required reading before any prescription.

Pregnancy Contraindication

Resmetirom is contraindicated in pregnancy. The FDA label carries a clear warning: animal reproductive studies showed embryo-fetal toxicity at doses below the human therapeutic dose. No adequate human pregnancy data exist. Because MASH is most common in women of reproductive age with PCOS or metabolic syndrome, this is not an abstract concern.

Script for reproductive-age women:

"Resmetirom can harm a developing baby. Before we start this medication, I need you using reliable contraception. That means at least one highly effective method: a hormonal IUD, copper IUD, implant, or tubal ligation. A pill alone is acceptable only if you take it consistently every day. If you are planning a pregnancy in the next 12 months, we need to talk about whether now is the right time to start."

Resmetirom's half-life is approximately 8 hours, and it is not expected to accumulate with normal dosing. A reasonable washout before conception is at minimum two weeks, though clinicians should use clinical judgment given the absence of human data.

Women Trying to Conceive

For a woman actively trying to conceive, the benefit-risk conversation changes substantially. MASH itself may impair fertility through insulin resistance and androgen excess (particularly in PCOS), but there are no data showing resmetirom improves fertility outcomes. Until long-term safety data in pregnancy exist, the drug should be stopped before a planned conception attempt.

Lactation

It is unknown whether resmetirom transfers into human breast milk. Animal data are not available in the label. The FDA label advises against breastfeeding during treatment. Because MASH is rarely urgent enough that it cannot be paused during a breastfeeding period, the practical guidance is: stop resmetirom, breastfeed, then reassess after weaning.

Counseling Scripts by Life Stage

These scripts are designed for use in telehealth visits. They are clinical frameworks, not legally reviewed informed-consent documents. Each should be adapted to the individual patient.

Script 1: Reproductive-Age Woman With PCOS (Ages 20-40)

Setting the context:

"Your liver biopsy shows stage F2 fibrosis with active MASH. Given that you also have PCOS, your insulin resistance has likely been driving fat accumulation in your liver for years. The good news is that we now have an FDA-approved medication specifically for this."

Explaining the mechanism (lay terms):

"Your thyroid hormone has a strong effect on how your liver processes fat. Resmetirom is a drug that targets the thyroid hormone receptor in your liver specifically, without affecting your heart or bones. Think of it as a targeted signal that tells your liver to burn fat and reduce inflammation."

Addressing the PCOS-thyroid overlap:

"Women with PCOS also have higher rates of autoimmune thyroid disease. Before we start, I want to confirm your TSH is current. If you are already on levothyroxine, this medication can lower your TSH slightly, meaning your levothyroxine dose may need to come down. We will recheck your TSH at eight weeks."

Contraception discussion:

"This medication cannot be taken during pregnancy. It caused problems in animal studies at doses lower than what you would be taking. I need you on reliable birth control before I send this prescription. Do you have that in place? Let us talk through the options if not."

Dose:

"We will start you at 80 mg once daily. If your BMI is 35 or above, the data from the clinical trial support 100 mg as the right starting dose. You take it with or without food."

Script 2: Perimenopausal Woman (Ages 42-55)

Setting the context:

"You are in perimenopause, and I want to explain something about your timing. Estrogen normally protects the liver from fat buildup. As your estrogen levels decline, your liver becomes more vulnerable. That is part of why MASH tends to worsen in this decade of life."

Hormone therapy intersection:

"If you are using estrogen-based hormone therapy for your perimenopausal symptoms, that is compatible with resmetirom. Oral estrogen does increase certain liver proteins, but there is no known pharmacokinetic interaction with resmetirom from the available data. I will monitor your liver enzymes at baseline, 4 weeks, and then quarterly."

Contraception note for perimenopausal women:

"If you are still having periods, even irregularly, pregnancy is possible. The same contraception requirement applies. We typically advise continuing contraception until you have been period-free for 12 consecutive months."

Lipid effects:

"One benefit you may notice: resmetirom lowered LDL cholesterol by about 16 to 19 percent in the clinical trial, as well as triglycerides. Given that cardiovascular risk rises in perimenopause, this is an added reason to treat the MASH now."

Script 3: Postmenopausal Woman (Ages 55+)

Setting the context:

"After menopause, the liver loses a significant amount of estrogen-driven protection. Women who were metabolically stable in their forties sometimes see MASH progress faster in their fifties and sixties. Treating fibrosis before it reaches the cirrhotic stage matters."

Cardiovascular framing:

"Your LDL, triglycerides, and liver health are connected. Resmetirom works on the same metabolic pathways that your thyroid would if it were functioning optimally in the liver. In women your age, the cardiovascular lipid benefit may be as clinically meaningful as the liver-specific benefit."

Thyroid disease prevalence:

"Hypothyroidism is common in postmenopausal women, and I want to check your TSH if we have not done so recently. Autoimmune thyroid disease affects up to 10% of women over 60. If you are on levothyroxine, your dose may need adjustment within the first two to three months of starting resmetirom."

Pregnancy and lactation:

"Given you are postmenopausal, pregnancy is not a concern. We can skip that part of the standard discussion and focus on monitoring."

Who Is Right for Resmetirom (and Who Is Not)

Women Likely to Benefit

• Biopsy-confirmed MASH with fibrosis stage F2 or F3
• Metabolic syndrome or PCOS-driven hepatic steatosis
• Elevated triglycerides and LDL alongside liver disease
• Postmenopausal women with progression despite lifestyle changes
• Women who have not responded adequately to 12 months of structured diet and exercise intervention

Women Who Should Not Start Resmetirom

• Pregnant or breastfeeding (contraindicated)
• Cirrhosis (F4 fibrosis) because MAESTRO-NASH excluded cirrhotic patients; the drug is not approved and safety data are absent in this group
• Severe renal impairment (creatinine clearance <30 mL/min) based on FDA label guidance
• Active gallstone disease or biliary obstruction (resmetirom increases bile acid flux)
• Concomitant use of strong CYP2C8 inhibitors without dose adjustment, as resmetirom is a CYP2C8 substrate

Drug Interactions Clinicians Must Review With Women

Several interactions are specifically relevant to female patients.

Oral Contraceptives

Resmetirom is a CYP2C8 substrate and an OATP1B1/1B3 inhibitor. The FDA label notes that co-administration with OATP substrates (including certain statins like rosuvastatin and pitavastatin) may increase their systemic exposure. Oral contraceptives containing ethinyl estradiol are not expected to be affected by this pathway, but clinicians should confirm which pill a patient is taking and check for pill-specific interactions.

Levothyroxine (Thyroid Replacement)

Women on levothyroxine represent a substantial portion of the MASH population. The MAESTRO-NASH supplement data noted that TSH decreased in some participants on resmetirom, consistent with increased hepatic thyroid hormone signaling. Practical guidance: recheck TSH at 8 weeks and adjust levothyroxine if TSH falls below the lower limit of normal.

Statins

Women with MASH and dyslipidemia are often already on a statin. Rosuvastatin and pitavastatin concentrations may rise by approximately 30 to 90% when co-administered with resmetirom due to OATP1B1 inhibition. The FDA label recommends dose-limiting rosuvastatin to 20 mg/day and pitavastatin to 2 mg/day during concurrent use.

Monitoring Plan: A Practical Timeline for Women

A structured monitoring approach reduces both adverse outcomes and patient anxiety.

| Timepoint | Lab or Assessment | |---|---| | Baseline | LFTs, TSH, fasting lipids, HbA1c, pregnancy test (if reproductive age), CMP | | 4 weeks | LFTs (ALT, AST) | | 8 weeks | TSH (adjust levothyroxine if needed), LFTs | | 12 weeks | Fasting lipids to assess LDL/TG response | | 24 weeks | MRI-PDFF or liver stiffness (if available) to confirm response | | 52 weeks | Consideration of repeat liver biopsy per institutional protocol | | Ongoing | Annual TSH, lipids, LFTs |

If ALT rises more than 3× the upper limit of normal and is accompanied by symptoms (jaundice, right upper quadrant pain, fatigue), stop resmetirom immediately and evaluate.

Evidence Gaps Specific to Women: An Honest Assessment

Women have been under-represented in liver disease trials for decades, and MAESTRO-NASH, while 54% female, did not pre-specify subgroup analyses by sex, menopausal status, or PCOS diagnosis. That is a limitation you should name plainly with patients.

What we do not yet know in women specifically:

• Whether the fibrosis response differs by hormonal status (premenopausal vs. Postmenopausal)
• Whether concurrent hormone therapy modifies efficacy or hepatotoxicity risk
• Whether women with PCOS respond differently than women with metabolic syndrome without PCOS
• Long-term bone mineral density effects in postmenopausal women, given that THR-β is expressed at low levels in osteoblasts

A 2023 AASLD practice guidance acknowledged that sex-stratified analyses in MASH trials remain a gap and called for future studies to report outcomes by sex and hormonal status. Telling your patient this honestly is not a weakness; it shows you are reading the real literature.

What to Say When Patients Ask About Weight Loss

Resmetirom is not a weight-loss drug. In MAESTRO-NASH, body weight decreased by approximately 2 to 3% in the treatment arms compared to placebo at 52 weeks, which is clinically modest. Women may ask whether they still need to lose weight. The answer: yes.

A practical script:

"Resmetirom works at the level of your liver cells. It does not tell your brain to eat less the way a GLP-1 drug does. If you are also trying to lose weight, we should talk about whether combining it with a GLP-1 receptor agonist makes sense for you. Those combinations are being studied, but we do not yet have head-to-head trial data to guide us."

The ongoing MAESTRO-NASH OUTCOMES trial will track cardiovascular events and liver-related mortality over several years. Until those data mature, resmetirom's long-term weight and cardiovascular benefit in women remains an open question.

Side Effects to Discuss With Every Patient

The most common adverse effects in MAESTRO-NASH were gastrointestinal and generally mild.

• Nausea: approximately 26% with 80 mg vs 16% with placebo (usually in first 4 weeks)
• Diarrhea: approximately 28% with 80 mg vs 17% with placebo
• Vomiting: approximately 10% vs 5% placebo

Script for side effects:

"Most women who start resmetirom notice some nausea or looser stools in the first few weeks. This usually settles down. Taking the tablet with a small meal can help. If you are vomiting and cannot keep it down after two weeks, call us. We have not seen serious liver-related side effects from this drug itself, but because you have liver disease, I want to monitor your liver enzymes at four weeks just to be sure."

A more serious concern is the theoretical risk of gallstone formation, because increasing bile acid flux can promote cholesterol gallstone development. Clinical trial rates of cholelithiasis were low, but women already have higher baseline rates of gallstone disease than men. Women who have had prior cholelithiasis or cholecystectomy should have this discussion documented.