Albumin is the liver’s main circulating protein that keeps fluid inside blood vessels and ferries many molecules—hormones, fatty acids, bilirubin, calcium, and drugs—through the bloodstream. By maintaining oncotic pressure, buffering acids, and binding toxins and oxidants, it supports stable circulation, tissue nourishment, and predictable drug effects across body systems.Most labs define a general reference range around the mid-3s to about 5. Values near the middle tend to signal steady liver synthesis, balanced hydration, and less systemic inflammation.When albumin runs low, it usually reflects reduced production (liver disease), increased loss (kidney urine loss or gut protein loss), dilution (heart failure or expanded plasma volume), or inflammation, where albumin drops as a negative acute-phase reactant. The physiologic result is less oncotic pull: ankles swell, ascites may appear, lungs can feel heavy, and wounds heal slowly. Drug binding falls, raising free drug levels, and total calcium may look low because less is carried on albumin. Pregnancy commonly shows lower values from hemodilution; infants can be slightly lower; older adults with low albumin often exhibit frailty and higher illness risk. Men and women have similar ranges.Higher albumin is uncommon from overproduction; it most often signals hemoconcentration from dehydration. People may notice thirst, dizziness, or rapid pulse; total calcium can appear high simply from increased protein binding.Big picture, albumin integrates liver function, vascular integrity, kidney and gut losses, hydration, and inflammation. Persistently low levels track with higher risks in surgery, hospitalization, and chronic disease, making albumin a powerful window into whole-body resilience and long-term outcomes.
