In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Patients with stage D2 - 3 disease , abnormal hemoglobin level or renal and liver function tests that were higher than the upper limits were excluded from the study .
### Output Text:
Patients with stage D2 - 3 disease , abnormal hemoglobin level or renal and liver function tests that were higher than the upper limits were excluded from the study . 