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NAFLD

REVIEWED BY
Bill Maish, MD
Clinical Content Consultant
Published
May 30, 2026
Last updated
May 30, 2026
Key takeaway:

Blood testing for NAFLD measures ALT, AST, GGT, triglycerides, HDL, LDL, ApoB, and AIP to assess hepatocellular injury and atherogenic metabolic dysfunction that drives fatty liver progression. Low HDL is the critical outlier flagging insulin resistance. Tracking improving enzymes, triglycerides, LDL, and ApoB (optimal AIP below ~0.11) confirms interventions are reducing liver fat and cardiovascular risk.

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Table of contents

NAFLD and the Liver Markers That Surface It

NAFLD biomarkers are molecules in blood that mirror what’s happening inside the fatty liver. When liver cells (hepatocytes) accumulate fat and become stressed, they leak enzymes and release cell fragments; as inflammation escalates, immune signals (cytokines) rise; if damage persists, scar-building ramps up and extracellular matrix fragments enter the bloodstream. Measuring selected markers from these pathways gives a real-time read on liver fat stress (steatosis), injury and inflammation (steatohepatitis), and scarring (fibrosis). This matters because most people feel fine while damage silently progresses. Blood testing can flag risk early, estimate disease activity, and monitor whether lifestyle or medicines are calming injury or slowing scar formation—often reducing the need for imaging or biopsy. In short, NAFLD biomarkers translate the liver’s biology into numbers that help detect disease, gauge severity, and follow change over time, so decisions can be made sooner and more safely.

Why a Quiet Liver Still Deserves Attention

Blood tests for NAFLD track two intertwined stories: how injured or stressed the liver is, and how the body is trafficking fats and lipoprotein particles. Enzymes such as ALT, AST, and GGT reflect hepatocyte injury and bile duct stress, while triglycerides, HDL, LDL, ApoB, and the Atherogenic Index of Plasma (AIP = log10[TG/HDL]) reflect insulin resistance, VLDL export, and cardiovascular risk—the systemic context in which NAFLD develops.For enzymes, healthier values generally sit in the lower part of the lab range: ALT and AST in the lower half, GGT low-normal. Triglycerides are best toward the low end, HDL toward the high end, and LDL and ApoB toward the low end; AIP is most favorable when low, ideally below about 0.11. Women typically have lower ALT cutoffs and higher HDL than men; adolescents have wider normal ranges during growth; in pregnancy, triglycerides rise and GGT tends to fall.When values are low, ALT/AST/GGT usually indicate little ongoing liver-cell injury, though NAFLD can still be present—especially in women and older adults—with few or no symptoms. Low triglycerides, LDL, and ApoB suggest less atherogenic particle burden and lower hepatic fat export; people often feel well. Low HDL is the exception: a low value flags metabolic dysregulation (insulin resistance), often pairing with central weight gain and higher triglycerides; it is more common in men and in teens. In pregnancy, unexpectedly low HDL or triglycerides may be atypical.Big picture: NAFLD is a liver expression of whole-body metabolic signaling. These biomarkers link liver fat, adipose and muscle insulin sensitivity, and arterial risk, helping gauge not just liver health but future cardiovascular and diabetes outcomes, even when imaging or symptoms are silent.

What Blood Work Captures — and What Imaging Is Still Needed For

Non-alcoholic fatty liver disease (NAFLD) is a condition where excess fat builds up in the liver, affecting how your body manages energy, metabolism, and inflammation. Because the liver is central to processing nutrients, regulating cholesterol, and filtering toxins, NAFLD can influence cardiovascular health, cognition, hormone balance, and immune function. At Superpower, we assess NAFLD risk and liver health by measuring ALT, AST, GGT, Triglycerides, HDL, LDL, ApoB, and AIP.ALT (alanine aminotransferase), AST (aspartate aminotransferase), and GGT (gamma-glutamyl transferase) are enzymes found in liver cells. When liver cells are stressed or damaged, these enzymes leak into the bloodstream, signaling liver injury or inflammation. Triglycerides are fats carried in the blood; high levels often accompany NAFLD and reflect how the liver handles fat. HDL (high-density lipoprotein) and LDL (low-density lipoprotein) are cholesterol carriers; ApoB is a protein on LDL particles, and AIP (Atherogenic Index of Plasma) is a calculated marker that reflects the balance between protective and harmful blood lipids.Healthy ALT, AST, and GGT levels suggest stable liver cell function and minimal inflammation. Balanced triglycerides, HDL, LDL, and ApoB indicate that the liver is effectively managing fat and cholesterol, reducing the risk of further liver damage and cardiovascular complications. A favorable AIP points to a lower risk of fatty buildup in both the liver and blood vessels.Interpretation of these biomarkers can be influenced by factors such as age, sex, pregnancy, acute illness, medications, and laboratory methods. These variables may shift results, so context is important when evaluating liver and metabolic health.

FAQs

NAFLD blood testing looks for liver cell injury and the metabolic pattern that drives fat buildup in the liver. It cannot diagnose NAFLD by itself but helps flag risk and monitor change over time. Superpower tests your blood for ALT, AST, GGT (liver enzymes) and Triglycerides, HDL, LDL, ApoB, and AIP (lipid/particle markers). Enzymes reflect hepatocellular stress; lipid and ApoB/AIP patterns reflect insulin resistance and atherogenic particle burden linked to fatty liver. Results are interpreted alongside clinical context, fibrosis scores, and imaging when needed.

NAFLD is often silent. These tests detect early liver stress and the cardiometabolic pattern that precedes fibrosis and complications. ALT, AST, and GGT signal hepatocellular or cholestatic injury; Triglycerides, HDL, LDL, ApoB, and AIP reveal atherogenic, insulin‑resistant physiology that drives fatty liver. Together they help stratify risk, establish a baseline, and track trajectory over time. They also illuminate cardiovascular risk that commonly travels with NAFLD.

Yes. With Superpower, our team member can organise a blood draw in your home. We collect ALT, AST, GGT, Triglycerides, HDL, LDL, ApoB, and AIP in one visit and deliver clear, contextual results.

Start with a baseline. If results are abnormal or you’re at higher metabolic risk, repeat every 3–6 months to assess trend and stability. If results are stable and low risk, annual testing is reasonable. After any major change that could affect liver enzymes or lipids, recheck on a similar cadence to confirm the new steady state.

Fasting status strongly affects Triglycerides and AIP. Alcohol can raise GGT and Triglycerides. Recent strenuous exercise or muscle injury can elevate AST and sometimes ALT. Medications and supplements (for example statins, fibrates, niacin, acetaminophen, some herbals) can shift enzymes and lipids. Acute illness, thyroid disorders, pregnancy, dehydration, and timing of the draw also influence values.

Fast 8–12 hours to standardize Triglycerides and AIP; water is fine. Avoid alcohol for 24–48 hours and strenuous exercise for 24 hours to reduce transient enzyme spikes. Take prescribed medicines as directed unless your clinician advises otherwise. Come well hydrated and, if possible, schedule when you’re not acutely ill.

References

  1. Chalasani, N., Younossi, Z., Lavine, J. E., Charlton, M., Cusi, K., Rinella, M., Harrison, S. A., Brunt, E. M., & Sanyal, A. J. (2018). The diagnosis and management of nonalcoholic fatty liver disease: Practice guidance from the American Association for the Study of Liver Diseases. Hepatology, 67(1), 328-357. https://doi.org/10.1002/hep.29367
  2. Younossi, Z. M., Koenig, A. B., Abdelatif, D., Fazel, Y., Henry, L., & Wymer, M. (2016). Global epidemiology of nonalcoholic fatty liver disease-Meta-analytic assessment of prevalence, incidence, and outcomes. Hepatology, 64(1), 73-84. https://doi.org/10.1002/hep.28431
  3. Targher, G., Byrne, C. D., & Tilg, H. (2020). NAFLD and increased risk of cardiovascular disease: Clinical associations, pathophysiological mechanisms and pharmacological implications. Gut, 69(9), 1691-1705. https://doi.org/10.1136/gutjnl-2020-320622
  4. Baneu, P., Văcărescu, C., Drăgan, S. R., Cirin, L., Lazăr-Höcher, A. I., Cozgarea, A., Faur-Grigori, A. A., Crișan, S., Gaiță, D., Luca, C. T., & Cozma, D. (2024). The triglyceride/HDL ratio as a surrogate biomarker for insulin resistance. Biomedicines, 12(7), 1493. https://doi.org/10.3390/biomedicines12071493
  5. McCracken, E., Monaghan, M., & Sreenivasan, S. (2018). Pathophysiology of the metabolic syndrome. Clinics in Dermatology, 36(1), 14-20. https://doi.org/10.1016/j.clindermatol.2017.09.004

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