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: Proteinuria increased significantly from a median of 0 . 13 g / day ( range 0 - 5 . 7 ) preswitch to 0 . 23 g / day ( 0 - 9 . 88 ) at 24 months postswitch ( p = 0 . 0024 ) .
### Output Text:
Proteinuria increased significantly from a median of 0 . 13 g / day ( range 0 - 5 . 7 ) preswitch to 0 . 23 g / day ( 0 - 9 . 88 ) at 24 months postswitch ( p = 0 . 0024 ) . 