Medical Terminology for Low Hemoglobin
The medical term for low hemoglobin is "anemia," which is defined as a reduction of hemoglobin concentration, red-cell count, or packed cell volume below normal levels. 1
Standard Definition and Terminology
Anemia is the universally accepted medical term for low hemoglobin, not "hypohemoglobinemia" (which is rarely used in clinical practice). 1
- Hemoglobin is the preferred measurement over hematocrit for diagnosing anemia because it is more reproducible across laboratories, has lower variability, and is not affected by sample storage time or patient-specific variables like serum glucose. 1
Classification by Severity
Anemia is further classified based on hemoglobin levels: 1
- Mild anemia: Hemoglobin ≤11.9 g/dL and ≥10 g/dL
- Moderate anemia: Hemoglobin ≤9.9 g/dL and ≥8.0 g/dL
- Severe anemia: Hemoglobin <8.0 g/dL
Diagnostic Thresholds
For adult males, anemia is defined as hemoglobin below 130 g/L (13.0 g/dL), with the normal reference range being 130-170 g/L. 2
- In chronic kidney disease patients specifically, anemia is diagnosed at hemoglobin below 135 g/L in adult males. 2
Morphological Classification
Anemia can be further characterized by red blood cell appearance: 1
- Normochromic and normocytic anemia: Normal-appearing red cells (common in chronic disease and CKD)
- Microcytic hypochromic anemia: Small, pale red cells (typical of iron deficiency and thalassemia) 3, 4
Important Clinical Caveat
The term "functional anemia" is sometimes used in specific contexts like methemoglobinemia, where oxygen delivery is impaired despite normal hemoglobin levels, but this is distinct from true anemia. 1