NAFLD / MASLD in Special Populations: Diagnosis, Risk, and Treatment Considerations

Why Special Populations Require a Different Approach

Standard MASLD screening and treatment algorithms were developed primarily in middle-aged adults with obesity and type 2 diabetes. These pathways miss or misclassify disease in populations where body composition, hormonal milieu, comorbid drug exposures, or organ function differ substantially from the reference cohort.

The 2023 multi-society Delphi consensus that introduced the MASLD nomenclature defined diagnostic criteria as hepatic steatosis of 5 percent or greater by imaging plus at least one cardiometabolic risk factor, including elevated BMI, type 2 diabetes, hypertension, or dyslipidemia 1. That framework works well for most adults. It works less well for a 9-year-old with obesity, a lean 32-year-old woman of South Asian descent, or a 70-year-old on immunosuppression after liver transplant. Each of these patients may harbor significant hepatic steatosis or fibrosis while falling outside conventional detection pathways. The American Association for the Study of Liver Diseases (AASLD) practice guidance acknowledges that "special populations require tailored diagnostic and management strategies" beyond general screening recommendations 2.

Pediatric MASLD: The Youngest Patients at Risk

MASLD is now the most common chronic liver disease in children and adolescents in high-income countries. A landmark autopsy study by Schwimmer et al. found hepatic steatosis in 9.6 percent of all children aged 2 to 19, rising to 38 percent in children with obesity 3.

Pediatric MASLD differs histologically from adult disease. The predominant pattern in children, sometimes called type 2 NASH, features portal-predominant inflammation and fibrosis rather than the zone 3 (perisinusoidal) pattern seen in most adults 4. This distinction matters because FibroScan and non-invasive fibrosis scores validated in adults (FIB-4, NFS) perform poorly in pediatric cohorts.

Diagnosis typically begins with ALT screening in children with obesity or overweight starting at age 9 to 11, as recommended by the American Academy of Pediatrics. Ultrasound confirms steatosis; MRI-PDFF (proton density fat fraction) provides quantification when needed. Biopsy remains the reference standard for staging fibrosis and distinguishing simple steatosis from MASH in this age group.

Treatment is anchored in lifestyle modification. No pharmacotherapy is FDA-approved for pediatric MASLD. The TONIC trial (N=173) tested vitamin E (800 IU daily) and metformin in children with biopsy-confirmed NASH; vitamin E achieved NASH resolution in 58 percent of patients versus 28 percent with placebo, while metformin showed no benefit over placebo 5. GLP-1 receptor agonists approved for pediatric obesity (semaglutide 2.4 mg is approved for adolescents aged 12 and older) may offer hepatic benefits, though dedicated pediatric MASLD trials are still underway. Resmetirom's label is restricted to adults, so off-label pediatric use has no supporting evidence.

Lean MASLD: When BMI Is Misleading

The assumption that fatty liver disease requires obesity is wrong. Approximately 10 to 20 percent of individuals with MASLD have a BMI below 25 kg/m² (or below 23 kg/m² in Asian populations), a phenotype termed lean MASLD 6. Lean MASLD is especially prevalent in South Asian, East Asian, and Hispanic populations, where visceral adiposity and insulin resistance can develop at lower body weights.

A meta-analysis by Ye et al. pooled 93 studies (over 10.5 million participants) and reported a global prevalence of lean NAFLD at 5.1 percent, with the highest rates in South America (6.8%) and Asia (5.2%) 7. Lean MASLD patients are not at low risk. The same meta-analysis found that lean individuals with NAFLD had higher all-cause mortality compared to lean individuals without NAFLD (hazard ratio 1.54 to 95% CI 1.18 to 2.00).

Genetic factors contribute. The PNPLA3 I148M variant (rs738409), strongly associated with hepatic fat accumulation independent of insulin resistance, is enriched in lean MASLD populations. Screening in lean patients should not rely solely on metabolic syndrome criteria. Clinicians should consider hepatic steatosis evaluation in lean individuals with unexplained transaminase elevations, polycystic ovary syndrome, or a first-degree relative with cirrhosis or hepatocellular carcinoma.

Treatment follows the same lifestyle and pharmacologic principles as MASLD in patients with obesity, though weight loss targets differ. Even a 3 to 5 percent reduction in body weight can improve hepatic steatosis, while a 7 to 10 percent reduction is typically needed for MASH resolution in all populations 8.

MASLD in Pregnancy

Pregnancy introduces physiological insulin resistance, increased hepatic lipogenesis, and rising estrogen levels, all of which can influence hepatic fat metabolism. Pre-existing MASLD may worsen during pregnancy, and gestational MASLD has been associated with higher rates of gestational diabetes, pre-eclampsia, and preterm delivery.

A Swedish cohort study (N=1.17 million deliveries) found that women with a diagnosis of NAFLD before or during pregnancy had a 2.6-fold increased risk of pre-eclampsia and 1.8-fold increased risk of gestational diabetes compared to women without NAFLD 9. The clinical challenge is distinguishing MASLD from pregnancy-specific liver conditions: acute fatty liver of pregnancy (AFLP), intrahepatic cholestasis of pregnancy (ICP), and HELLP syndrome. AFLP is a medical emergency requiring delivery, while MASLD alone typically does not mandate obstetric intervention.

Diagnostic imaging in pregnancy is limited. Ultrasound is safe and first-line. MRI without gadolinium is acceptable but rarely pursued solely for MASLD staging. Liver biopsy is reserved for diagnostic uncertainty where the differential includes AFLP. FibroScan data in pregnant women remain sparse.

Management focuses on optimizing metabolic health: glycemic control, blood pressure management, and appropriate gestational weight gain. Pioglitazone, vitamin E (at pharmacologic doses), GLP-1 receptor agonists, and resmetirom are all contraindicated in pregnancy. Metformin, sometimes used for gestational diabetes, has no proven benefit specifically for MASLD in the pregnant population.

MASLD in Elderly Adults

MASLD prevalence peaks in the sixth and seventh decades of life, then appears to decline, though this drop may partly reflect competing mortality from cardiovascular disease, hepatocellular carcinoma, and decompensated cirrhosis removing affected individuals from prevalence surveys.

Older adults with MASLD face compounding risks. Sarcopenia (age-related muscle loss) reduces the already limited accuracy of BMI as a surrogate for metabolic health. A Japanese cohort study of 1,365 adults older than 65 found that sarcopenic NAFLD was associated with a significantly higher risk of advanced fibrosis (OR 2.4 to 95% CI 1.3 to 4.4) compared to NAFLD without sarcopenia 10. This combination, sometimes called sarcopenic obesity, creates a phenotype where patients have high visceral fat but low muscle mass, making standard fibrosis calculators less reliable.

The AASLD and European Association for the Study of the Liver (EASL) both note that FIB-4 cut-offs may need adjustment in patients over 65 because age itself inflates the index 2. An FIB-4 value of <1.3 (the standard low-risk threshold) excludes fewer elderly patients from further evaluation, necessitating secondary testing with FibroScan or ELF (Enhanced Liver Fibrosis) score.

Treatment in elderly patients must account for polypharmacy, fall risk (relevant for exercise prescriptions), and renal function. Pioglitazone is effective for MASH resolution but carries risks of fluid retention, heart failure exacerbation, and fracture, each of which is amplified in older adults. Vitamin E at 800 IU daily remains an option for non-diabetic elderly patients with biopsy-proven NASH, though the SELECT trial raised concerns about prostate cancer risk in men taking high-dose vitamin E 11. Resmetirom, approved for adults with MASH and F2-F3 fibrosis, was studied in the MAESTRO-NASH trial (N=966), where the mean participant age was 56; subgroup analyses in older adults showed consistent efficacy but clinicians should monitor thyroid function carefully given age-related thyroid vulnerability 12.

MASLD in People Living with HIV

Prevalence of hepatic steatosis among people living with HIV (PLWH) ranges from 35 to 50 percent in imaging-based studies, exceeding general population estimates 13. Several factors converge to drive this elevated risk. Certain antiretroviral therapy (ART) classes, particularly older nucleoside reverse transcriptase inhibitors (stavudine, didanosine) and some protease inhibitors (lopinavir/ritonavir), promote lipodystrophy, dyslipidemia, and insulin resistance. HIV infection itself triggers chronic immune activation that may accelerate hepatic inflammation and fibrosis independent of metabolic risk factors.

The diagnostic approach in PLWH follows general MASLD principles, but clinicians must exclude hepatitis B and C co-infection (present in a meaningful subset of PLWH) as alternative or contributing causes of liver disease. FIB-4 and APRI have been validated in HIV mono-infected populations and perform comparably to their accuracy in HIV-negative cohorts 14.

Management starts with ART regimen review. Switching from metabolically harmful agents to integrase strand transfer inhibitors (dolutegravir, bictegravir) or to the newer agent lenacapavir can improve lipid profiles and reduce hepatic fat accumulation. Lifestyle modification remains the cornerstone. Data on GLP-1 receptor agonists in PLWH with MASLD are limited but promising. A pilot study of semaglutide in 30 PLWH with MASLD showed a 32 percent relative reduction in hepatic fat fraction at 24 weeks 15. Drug interactions between GLP-1 receptor agonists and ART are minimal, making this class a reasonable therapeutic option pending larger trials. Dr. Jordan Lake, an HIV metabolic specialist at UT Health Houston, has noted that "the intersection of antiretroviral metabolic toxicity and MASLD creates a population that may benefit disproportionately from targeted hepatic therapies" 15.

MASLD and Chronic Kidney Disease

MASLD and chronic kidney disease (CKD) share common metabolic drivers: insulin resistance, systemic inflammation, and endothelial dysfunction. The relationship is bidirectional. MASLD increases incident CKD risk, and CKD may accelerate hepatic fibrosis progression through uremic toxin-mediated pathways.

A meta-analysis by Mantovani et al. including 33 studies and over 63,000 participants found that NAFLD was associated with a 1.45-fold increased risk of incident CKD (95% CI 1.31 to 1.61), with the risk rising to 1.58-fold in patients with more severe liver disease 16. The AASLD guidance recommends screening for CKD (eGFR and urine albumin-to-creatinine ratio) in all patients with MASLD and established metabolic risk factors 2.

Treatment considerations shift significantly in patients with eGFR below 30 mL/min/1.73 m². Pioglitazone does not require dose adjustment for renal impairment but fluid retention risk increases. Metformin is contraindicated below eGFR 30. GLP-1 receptor agonists vary: semaglutide does not require renal dose adjustment, while exenatide is not recommended in severe renal impairment. Resmetirom's prescribing information does not exclude CKD patients, but the MAESTRO-NASH trial excluded individuals with eGFR below 40, so data in advanced CKD are absent 12.

SGLT2 inhibitors, while primarily indicated for diabetes, heart failure, and CKD, have shown modest hepatic fat reduction (approximately 3 to 4 percent absolute decrease in MRI-PDFF) and may serve dual purpose in patients with MASLD and CKD stage 2 to 3 17.

Post-Transplant MASLD Recurrence

Liver transplantation does not cure the metabolic milieu that produced MASLD. Recurrent steatosis is documented in 20 to 40 percent of recipients within the first 5 years, and de novo MASLD occurs at similar rates in patients transplanted for non-MASLD indications 18.

Post-transplant metabolic syndrome is driven by immunosuppressant side effects. Corticosteroids promote insulin resistance and central adiposity. Calcineurin inhibitors (tacrolimus, cyclosporine) contribute to new-onset diabetes after transplant (NODAT), which occurs in 10 to 30 percent of liver transplant recipients within the first year. Tacrolimus carries higher diabetogenic risk than cyclosporine. mTOR inhibitors (sirolimus, everolimus) cause dyslipidemia.

Monitoring recurrent MASLD requires protocol imaging. The AASLD recommends serial FibroScan or MRI-PDFF rather than repeated biopsy for longitudinal assessment in transplant recipients, reserving biopsy for cases where graft dysfunction raises concern for rejection, recurrent MASH, or de novo autoimmune hepatitis. Weight gain after transplantation is common (mean 5 to 10 kg in the first year), so early dietary counseling and exercise programs should be initiated before discharge.

Pharmacologic options are constrained. Pioglitazone can be considered but requires careful monitoring for fluid retention and edema, which overlap with calcineurin inhibitor nephrotoxicity symptoms. GLP-1 receptor agonists are increasingly studied in post-transplant populations; a retrospective analysis of 47 transplant recipients on liraglutide showed 4.2 percent mean weight loss at 6 months with no increase in rejection episodes 19. Resmetirom has not been studied in transplant recipients. Any new medication must be evaluated for interactions with immunosuppressants, particularly through CYP3A4 and P-glycoprotein pathways.

Screening and Risk Stratification Across Populations

A single screening protocol cannot serve all populations. The table below summarizes population-specific considerations.

For children, ALT screening begins at age 9 to 11 in those with obesity, with ultrasound as first-line imaging and biopsy for equivocal cases. For lean adults, clinicians should consider MASLD when transaminases are elevated even without metabolic syndrome, using MRI-PDFF for quantification. In pregnant patients, ultrasound is the only recommended imaging modality, with biopsy reserved for excluding AFLP. For elderly adults, FIB-4 requires age-adjusted interpretation, and FibroScan serves as a useful second-line tool. In PLWH, hepatitis B and C must be excluded before attributing steatosis to MASLD. CKD patients warrant simultaneous renal and hepatic staging. Post-transplant recipients need protocol-based FibroScan or MRI-PDFF surveillance.

The Endocrine Society's 2024 clinical practice guideline on MASLD recommends that "all patients with type 2 diabetes, prediabetes, or two or more metabolic risk factors should be screened for MASLD using FIB-4 as the initial assessment" 20. This recommendation applies across all special populations, with the caveat that FIB-4 interpretation requires clinical context in pediatric and elderly cohorts.

Patients who screen positive (FIB-4 ≥ 1.3, or ≥ 2.0 in adults over 65) should proceed to hepatology referral, FibroScan, or ELF testing. Those with confirmed F2 or greater fibrosis are candidates for pharmacotherapy, with resmetirom now available for adults with non-cirrhotic MASH and F2-F3 fibrosis based on the MAESTRO-NASH results showing MASH resolution without fibrosis worsening in 25.9 percent of patients on resmetirom 80 mg versus 9.7 percent on placebo at 52 weeks 12.