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: Acute renal insufficiency ( ARI ) after high - dose melphalan was defined by a minimum increase of 0 . 5 mg / dL ( 44 micromol / L ) in the serum creatinine level that is greater than 50 % of baseline immediately after conditioning .
### Output Text:
Acute renal insufficiency ( ARI ) after high - dose <span class="chemical">melphalan</span> was defined by a minimum increase of 0 . 5 mg / dL ( 44 micromol / L ) in the serum <span class="chemical">creatinine</span> level that is greater than 50 % of baseline immediately after conditioning . 