The liver plays the major role in producing proteins that are secreted into the blood, including major plasma proteins, factors in hemostasis and fibrinolysis, carrier proteins, hormones, prohormones and apolipoprotein:

Major plasma proteins

All plasma proteins except Gamma-globulins are synthesised in the liver.^[1]

• Human serum albumin, osmolyte and carrier protein
• α-fetoprotein, the fetal counterpart of serum albumin
• Soluble plasma fibronectin, forming a blood clot that stops bleeding
• C-reactive protein, opsonin on microbes,^[2] acute phase protein
• Various other globulins

Factors in hemostasis and fibrinolysis

• Stimulators of coagulation:
  • All factors in the coagulation cascade.^[3]
  • While the endothelium does produce some factor VIII, the majority of factor VIII is produced in the liver.^[4]
• Inhibitors of coagulation: Inactivate an enormous variety of proteinases
  • α2-macroglobulin
  • α1-antitrypsin
  • Antithrombin III
  • Protein S
  • Protein C
• Fibrinolysis: Breakdown of fibrin clots
  • Plasminogen
• Inhibitors of fibrinolysis
  • α2-antiplasmin
• Complement components C1-9, complement component 3 (C3)

Carrier proteins

• Albumin, carries thyroid hormones and other hormones, particularly fat soluble ones, fatty acids to the liver, unconjugated bilirubin, many drugs and Ca²⁺
• Ceruloplasmin, carries copper
• Transcortin, carries cortisol, aldosterone and progesterone
• Haptoglobin, carries free hemoglobin released from erythrocytes
• Hemopexin, carries free heme released from hemoglobin
• IGF binding protein, carries insulin-like growth factor 1
• Major urinary proteins, carries pheromones in rodents
• Retinol binding protein, carries retinol
• Sex hormone-binding globulin, carries sex hormones, specifically testosterone and estradiol
• Thyroxine-binding globulin, carries the thyroid hormones thyroxine (T4) and 3,5,3’-triiodothyronine (T3)
• Transthyretin, carries the thyroid hormone thyroxine (T4)
• Transferrin, carries iron ions in the ferric form (Fe³⁺)
• Vitamin D-binding protein, carries vitamin D

Hormones

• FGF21, a protein hormone that induces mitochondrial oxidation of fatty acids, hepatic gluconeogenesis, and ketogenesis in response to fasting.
• Hepcidin, a peptide hormone that regulates iron homeostasis.
• Insulin-like growth factor 1, a polypeptide protein hormone which plays an important role in childhood growth and continues to have anabolic effects in adults
• Thrombopoietin, a glycoprotein hormone that regulates the production of platelets by the bone marrow

Prohormones

• Angiotensinogen, when converted to angiotensin causes vasoconstriction and release of aldosterone, in effect increasing blood pressure

Apolipoproteins

• Almost all apolipoprotein, except apo B48 (produced by intestine)