The NASH medical abbreviation stands for nonalcoholic steatohepatitis, a type of fatty liver disease where extra fat inside liver cells is joined by swelling and damage to those cells, in people who drink little or no alcohol. Left active for years, that damage may build up scar tissue (fibrosis), and some people go on to cirrhosis.
Liver specialty groups have renamed the condition metabolic dysfunction associated steatohepatitis, or MASH, so you may see either term in records. NASH still appears widely in older notes, insurance forms and research. Further down is a letter by letter breakdown, a map from the old names to the new ones, and examples of NASH in real reports.
At a glance
Stands for
Nonalcoholic steatohepatitisNewer name
MASH, metabolic dysfunction associated steatohepatitisWord roots
Steato (fat) plus hepat (liver) plus itis (inflammation)Parent condition
NAFLD, now MASLDUsed in
Hepatology, gastroenterology, primary care, pathologyDo not confuse with
ASH, alcohol related steatohepatitis
What the NASH medical abbreviation describes
Many people have some extra fat in the liver, a condition for years labeled NAFLD (the nonalcoholic fatty liver disease name). In a smaller group, that fat comes with inflammation and swelling of liver cells, which pathologists call ballooning. That inflamed form is NASH. It matters because inflammation is what drives scarring, and the amount of scarring is the main thing that shapes long term outlook.
NASH is closely tied to metabolic conditions such as type 2 diabetes, excess body weight, high blood pressure and abnormal blood fats. It often causes no symptoms for years, so it often turns up by chance when liver enzymes or a scan are checked for some other purpose.
How the renamed liver terms line up
| Before the renaming | After | Scope |
|---|---|---|
| NAFLD | MASLD | Fat buildup in liver cells tied to metabolic risk |
| NASH | MASH | Fat buildup plus inflammation and ballooning |
| NAFL | MASL | Fat buildup without notable inflammation |
| None | MetALD | Metabolic fat buildup with moderate drinking added |
The renaming dropped the words nonalcoholic and fatty, which some found stigmatizing, and put the focus on metabolic causes. Most people who had NASH under the old definition meet the new MASH definition.
How NASH appears in a report
Biopsy result: "NASH with stage 2 fibrosis." This means the liver sample shows fat, inflammation and cell injury, and there is moderate scarring. Fibrosis is usually staged from 0, no scarring, to 4, cirrhosis.
Other lines may mention ALT and AST, liver enzymes that can be raised, or a FIB-4 score, a calculation from routine labs that estimates scarring. Imaging that measures liver stiffness is often used instead of a biopsy. Normal enzyme limits differ from one lab to the next, so compare any value with the limits shown on that same report.
Questions worth raising with a liver specialist
If NASH or MASH appears in your record, useful questions include what stage of fibrosis has been found, how it was measured, how often it will be checked, and which other conditions such as diabetes or blood pressure are being managed alongside it. Ask, too, whether any of your current medicines affect the liver.
This is general information about a liver diagnosis label. A liver specialist or your regular clinician is the one to interpret your own numbers and next steps.
Frequently asked questions
What does NASH stand for in medical terms?
NASH stands for nonalcoholic steatohepatitis. It is fatty liver disease with inflammation and liver cell damage in someone who drinks little or no alcohol.
Is NASH a medical acronym or an initialism?
NASH is an acronym, because people say it as one word rather than letter by letter. The letters come from NonAlcoholic SteatoHepatitis, two taken from each of the two words.
Is NASH the same as MASH?
They describe essentially the same condition. MASH is the newer name, metabolic dysfunction associated steatohepatitis, and many records now use it in place of NASH.
What is the difference between NAFLD and NASH?
NAFLD is the broad term for extra fat in the liver. NASH is the more serious subset where that fat comes with inflammation and injury that can lead to scarring.
Can NASH cause cirrhosis?
It can in some people. Ongoing inflammation may lead to fibrosis, and advanced fibrosis can progress to cirrhosis, which is why scarring is monitored over time.