Low MCHC Causes and Diagnostic Approach

Primary Cause: Iron Deficiency Anemia

Low MCHC specifically indicates hypochromic red blood cells with decreased hemoglobin content per unit volume, reflecting severe iron-restricted erythropoiesis, as noted by the American Heart Association 1, 2

Thalassemia minor produces microcytic anemia with low MCHC but can be distinguished from iron deficiency by a normal or low RDW (<14.0%), according to the Centers for Disease Control and Prevention 3, 4
Chronic inflammatory conditions can cause low MCHC, though less commonly than iron deficiency, as stated by the National Comprehensive Cancer Network 4, 5
Sideroblastic anemia represents a rare cause of microcytic hypochromic anemia with low MCHC, also noted by the National Comprehensive Cancer Network 4, 5

In cyanotic heart disease patients, low MCHC indicates iron deficiency anemia superimposed on polycythemia, creating a particularly dangerous situation, as reported by the American Heart Association 1, 2
Iron deficiency in these patients produces microcytic hypochromic red cells that are rigid and less deformable in microcirculation, according to the American Heart Association 1, 2

The minimum workup for suspected low MCHC must include a complete blood count with RBC indices, serum ferritin, and C-reactive protein, as recommended by the National Comprehensive Cancer Network and the European Crohn’s and Colitis Organisation 4, 6