From the Research
tHb on an ABG refers to total hemoglobin concentration, which measures the amount of hemoglobin present in the blood sample, with normal values typically ranging from 12-17 g/dL for men and 11.5-15.5 g/dL for women, as supported by recent studies 1, 2. This measurement is crucial because hemoglobin is the protein in red blood cells responsible for carrying oxygen throughout the body. When interpreting an ABG, the tHb value helps clinicians assess oxygen-carrying capacity and can indicate conditions like anemia (if low) or polycythemia (if high). The tHb measurement complements other ABG parameters such as pH, PaO2, PaCO2, and oxygen saturation to provide a comprehensive picture of a patient's respiratory and metabolic status. Some studies have highlighted the importance of accurate tHb measurement, including a 2020 study that found differences in tHb values between conductivity-based and absorbance-based measurement methods 3. Additionally, a 2013 study noted that arterial blood gas analysers may not always provide accurate haemoglobin concentrations compared to standard venous analysers 4. However, the most recent and highest quality study on the topic of anemia and hemoglobin levels, published in 2023, emphasizes the importance of patient symptoms and preferences in conjunction with hemoglobin concentration in guiding transfusion practice 1. Key points to consider when interpreting tHb on an ABG include:
- Normal tHb values and their variation between men and women
- The importance of accurate tHb measurement in assessing oxygen-carrying capacity
- The potential for differences in tHb values between different measurement methods
- The need for caution when interpreting tHb values in critically ill patients, as supported by studies 5, 4.