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: Other than elevation of serum creatinine levels , characteristic clinical manifestations and abnormal laboratory findings are not frequently present .
### Output Text:
Other than elevation of serum <span class="chemical">creatinine</span> levels , characteristic clinical manifestations and abnormal laboratory findings are not frequently present . 