What is the normal range for adult hemoglobin?

Normal hemoglobin (Hgb): 12-16 g/dL for adult females; 14-18 g/dL for adult males. Lower values indicate anemia; higher values indicate polycythemia. Anemia (Hgb below normal): symptoms include fatigue, weakness, pallor, shortness of breath, tachycardia, palpitations, dizziness. Common causes: blood loss (acute or chronic), iron deficiency (most common cause worldwide), B12 deficiency, folate deficiency, chronic disease, kidney disease (decreased erythropoietin), bone marrow disorders, hemolysis. Workup includes hematocrit (Hct, typically 3× the Hgb value, 36-48% females, 42-54% males), MCV (mean corpuscular volume — distinguishes microcytic, normocytic, macrocytic anemias), reticulocyte count, iron studies, B12, folate, kidney function. Polycythemia (Hgb above normal): causes include dehydration, chronic hypoxia (COPD, smoking, sleep apnea, high altitude), polycythemia vera. Transfusion thresholds vary but generally: symptomatic anemia or Hgb below 7-8 g/dL in stable patients; higher threshold for cardiac patients (around 8-10). NCLEX commonly tests hemoglobin ranges and indications for assessment of bleeding.