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: Chronically elevated prolactin levels in children with prolactinomas may be associated with arrested growth and development resulting in either delayed puberty or short stature .
### Output Text:
Chronically elevated prolactin levels in children with prolactinomas may be associated with arrested growth and development resulting in either delayed puberty or short stature . 