Yes, the liver is a gland. It is, in fact, the largest gland in the human body, weighing around 1.8 kg in men and 1.4 kg in women. What makes the liver unusual is that it functions as both an exocrine gland (secreting bile through ducts into the digestive tract) and an endocrine gland (releasing hormones, proteins, and signaling molecules directly into the bloodstream). This dual role puts it in the same category as the pancreas, though the liver’s range of functions is far broader than any other gland.
What Makes an Organ a Gland
A gland is any organ or tissue that produces and releases substances the body needs, either through a duct (exocrine) or directly into the blood (endocrine). The liver does both. Its cells, called hepatocytes, are arranged in honeycomb-like structures called lobules. Within each lobule, hepatocytes sit in rows separated by tiny blood-filled channels called sinusoids. Blood flows through these sinusoids in one direction while bile, the liver’s main exocrine product, flows in the opposite direction toward bile ducts at the lobule’s edges. This architecture allows the same cells to secrete products in two directions simultaneously: into ducts for digestion and into the bloodstream for the rest of the body.
The Liver’s Exocrine Role: Bile Production
The liver’s most obvious glandular function is producing bile. A healthy adult liver generates roughly 800 to 1,000 milliliters of bile every day. Bile is a fluid containing bile salts that break dietary fats into smaller droplets, a process called emulsification, so your intestines can absorb them. Without bile, your body would struggle to digest and absorb fats and fat-soluble vitamins.
Bile flows from the hepatocytes through a branching network of tiny ducts that merge into larger ones, eventually reaching the gallbladder for storage. When you eat a meal containing fat, the gallbladder contracts and releases bile into the upper part of the small intestine. This duct-based delivery system is what qualifies bile production as an exocrine function.
The Liver’s Endocrine Role: Secretions Into the Blood
The liver’s endocrine side is less well known but equally important. It receives about 25% of the heart’s total blood output, and it uses that massive blood flow to distribute a wide array of signaling molecules to distant organs.
The most familiar of these are plasma proteins. The liver synthesizes the majority of the proteins circulating in your blood, the most abundant being albumin, which maintains fluid balance and carries substances through the bloodstream. It also produces clotting factors, the proteins that stop bleeding when you’re injured.
Beyond structural proteins, the liver releases dozens of specialized signaling molecules now collectively called hepatokines. These influence growth, blood pressure, blood cell production, iron balance, calcium levels, and how your body responds to insulin. It also secretes lipid-carrying particles that transport cholesterol and triglycerides to tissues that need them, along with energy molecules like ketone bodies that fuel the brain and muscles during fasting. A 2019 review in Endocrine Reviews documented a large and growing list of these liver-derived signals, noting that the organ secretes proteins, metabolites, and even small RNA molecules that exert powerful effects on metabolism throughout the body.
Blood Sugar Regulation
One of the liver’s most critical glandular functions is keeping your blood sugar stable. After a meal, when blood glucose rises, the liver pulls glucose out of the bloodstream and stores it as glycogen, a compact energy reserve. When you haven’t eaten for a few hours, the liver breaks that glycogen back down and releases glucose into the blood. During longer fasts, once glycogen stores run out, the liver switches to manufacturing brand-new glucose from other raw materials like amino acids and lactate, a process called gluconeogenesis. This is why people with severe liver disease can develop dangerously low blood sugar: the gland responsible for maintaining it is no longer functioning properly.
How the Liver Compares to the Pancreas
The pancreas is the organ most often cited as a dual-function gland, and it makes a useful comparison. The pancreas has clearly separated structures for its two roles: clusters of cells called acini produce digestive enzymes that flow through ducts into the intestine (exocrine), while scattered clusters called islets of Langerhans release insulin and glucagon directly into the blood (endocrine). You can see this division under a microscope.
The liver’s dual function is organized differently. The same hepatocytes handle both jobs. A single liver cell can produce bile for the digestive tract while simultaneously releasing albumin, clotting factors, and signaling molecules into the bloodstream. This makes the liver less neatly compartmentalized than the pancreas but arguably more versatile. It also performs hundreds of metabolic tasks, including detoxification and nutrient processing, that go well beyond what we typically associate with a gland. That metabolic complexity is part of why people sometimes forget the liver qualifies as one.
The Liver’s Unique Ability to Regenerate
Unlike most glands, the liver can regrow after significant damage or surgical removal. Surgeons can remove up to 50% of a person’s liver, and the remaining tissue will grow back to nearly its original size within about a month. This regenerative capacity is so reliable that surgical teams plan liver cancer operations around it, aiming to leave a minimum of 30% of the liver intact so it can recover. No other internal gland in the human body has this ability at anywhere near this scale, which makes the liver exceptional even among organs already considered remarkable.