Hemoglobin — Oxygen-Carrying Blood Protein

Hemoglobin is the primary functional component of erythrocytes, responsible for binding oxygen in pulmonary capillaries and releasing it to metabolising tissues. It also assists in returning carbon dioxide to the lungs. Normal reference ranges vary slightly between laboratories but generally fall between 120 and 160 grams per litre for adult women and 130 to 175 grams per litre for adult men.

In cancer care, low concentrations of hemoglobin signify anemia, a frequent complication. Anemia can develop because of tumour-induced blood loss, impaired bone marrow function, systemic inflammation, nutritional deficiencies, or the toxic effects of cytotoxic chemotherapy and radiation on rapidly dividing hematopoietic precursor cells.

Maintaining adequate hemoglobin levels is critical for your stamina, daily functioning, and quality of life. Significant drops in hemoglobin can lead to profound exhaustion and cardiovascular strain. From a clinical perspective, severe anemia may require treatment delays, dosage reductions, or supportive interventions so your body can recover. Adequate tissue oxygenation is also important because some cancer treatments, particularly radiotherapy, rely on oxygen within cells to produce maximum therapeutic effect against tumours.

Hemoglobin is measured via a standard full blood count (FBC), also called a complete blood count (CBC). This test requires a routine blood draw. When levels are low, doctors often order additional tests to uncover the cause. These may include serum ferritin, transferrin saturation, total iron-binding capacity, vitamin B12, and folate levels. Reticulocyte counts and stool tests for occult blood may also be performed to assess red blood cell production and gastrointestinal blood loss.

Low hemoglobin levels can occur across almost any cancer type, but they are particularly common in hematologic malignancies such as leukemia, lymphoma, and multiple myeloma, which directly disrupt bone marrow. They are also frequently observed in gastrointestinal cancers, including colorectal, gastric, and esophageal tumours, where slow, chronic internal bleeding often occurs. Patients receiving intensive systemic chemotherapy for lung, breast, or ovarian cancers also regularly experience treatment-related drops in hemoglobin.

Managing abnormal hemoglobin involves treating the underlying cause while alleviating symptoms. Mild anemia may be monitored or managed with oral or intravenous iron supplements, vitamin repletion, or dietary adjustments. In more pronounced or symptomatic cases, clinicians may prescribe erythropoiesis-stimulating agents (ESAs) to encourage bone marrow production, or administer packed red blood cell transfusions. Addressing low levels helps ensure chemotherapy schedules remain on track without prolonged interruptions.