Final answer:
The nurse should report the laboratory value of Hgb 6 g/dL to the provider.
Step-by-step explanation:
The nurse should report the laboratory value of Hgb 6 g/dL to the provider. In an adolescent client experiencing sickle cell crisis, a low hemoglobin level indicates severe anemia, which can be a life-threatening condition. The normal hemoglobin level for adolescents is usually around 12-16 g/dL, so a value of 6 g/dL is significantly below the expected range.