Albumin is a measure of your serum protein level in your blood.
Many of us ESRD patients lose protein in our urine (proteinuria); and the dietary restrictions on phosphorus mean that we eat less protein than we used to. The result can be poor protein levels, which can lead to malnutrition.
Malnutrition combined with the chronic inflammation that hemodialysis seems to cause is known to be a lethal combination, significantly shortening life expectancy.
http://www.ncbi.nlm.nih.gov/pubmed/14582032So it's very important to keep that albumin level above 4.0. Lower than that and you're prone to malnutrition.