What is one key laboratory value indicative of anemia or bleeding?

Hematocrit level is a crucial laboratory value used to assess the proportion of blood volume that is made up of red blood cells. It provides important information about the body's ability to carry oxygen. In cases of anemia, hematocrit levels typically decrease due to a lower number of red blood cells. Similarly, in the context of bleeding, hematocrit can also be affected; significant blood loss would lead to a drop in hematocrit levels as the volume of red blood cells decreases relative to plasma. Monitoring hematocrit levels is thus an effective way to evaluate an individual's blood status and can help guide further diagnosis and management of potential issues related to anemia or bleeding.

The other options do not directly relate to the diagnosis of anemia or bleeding. Electrolyte balance relates primarily to the levels of various ions in the body and is more about metabolic status than blood oxygen-carrying capacity. Liver enzyme levels reflect liver function and damage, while thyroid function tests evaluate hormonal balance, neither of which are indicative of anemia or bleeding.