Which condition would most likely lead to a high MCHC reading in a CBC?

A high mean corpuscular hemoglobin concentration (MCHC) indicates that red blood cells contain an unusually high amount of hemoglobin relative to their volume. One primary condition that can lead to elevated MCHC is dehydration. In dehydration, the plasma volume decreases, which effectively concentrates the red blood cells and their hemoglobin, resulting in an increased MCHC reading.

While conditions such as iron overload can also affect MCHC, they typically lead to other hematological changes and do not raise MCHC as directly as dehydration. Anemia and vitamin B12 deficiency usually result in a lower MCHC due to reduced hemoglobin synthesis, as the red blood cells may be poorly developed or fewer in number. Recognizing how dehydration impacts the ratio of hemoglobin to red blood cell volume is crucial for understanding why it is the most likely condition associated with a high MCHC in a complete blood count (CBC).