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: Fifty - eight patients ( 78 % ) had normal renal tests , whereas 16 patients ( 22 % ) had renal abnormalities .
### Output Text:
Fifty - eight patients ( 78 % ) had normal renal tests , whereas 16 patients ( 22 % ) had renal abnormalities . 