This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
The estimation of 3 methyl histidine in urine is used to study - 
Select and explain. 
A. Status of folate in the body, B. Renal disease, C. Skeletal muscle, D. Protein absorption in the gut
C: Skeletal muscle
Answer: C: Skeletal muscle 
Explanation: 3-Methylhistidine (3-MH) is a post-translationally modified amino acid which is excreted in human urine. Urinary concentrations of 3-methylhistidine serve as a reliable index of skeletal muscle protein breakdown in humans who have been subject to muscle injury. Ref Davidson 23rd edition pg 981