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: CONCLUSIONS : Low prevalences and effects of low testosterone and high prolactin in erectile dysfunction cannot justify their routine determination .
### Output Text:
CONCLUSIONS : Low prevalences and effects of low <span class="chemical">testosterone</span> and high prolactin in erectile dysfunction cannot justify their routine determination . 