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: This article presents a patient with hypoparathyroidism who was treated with calcium carbonate and calcitriol resulting in two admissions to the hospital for milk - alkali syndrome .
### Output Text:
This article presents a patient with hypoparathyroidism who was treated with <span class="chemical">calcium carbonate</span> and <span class="chemical">calcitriol</span> resulting in two admissions to the hospital for milk - alkali syndrome . 