This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Hamann's solution contains all of the following, EXCEPT: 
Select and explain. 
A. Na++, B. Ca++, C. Mg++, D. Lactate
C: Mg++
Answer: C: Mg++ 
Explanation: Hamann solution is a crystalloid solution used for intravenous administration, it is also known compound sodium lactate. Hamann solution contains: Na+ 131 mmol/L Cl- = 111 mmol/L Lactate = 29 mmol/L K+ = 5 mmol/L Ca++ = 2 mmol/L pH = 6.5 Osmolarity = 279 mosm/L Ref: The ICU Book By Paul L. Marino, Page 237