This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pathology
Procalcitonin is used as a marker for? 
Select and explain. 
A. Sepsis, B. Medullary carcinoma of thyroid, C. Vitamin D resistant rickets, D. parathyroid adenoma
A: Sepsis
Answer: A: Sepsis 
Explanation: Answer is option 1, sepsis Prompt diagnosis and treatment with appropriate antimicrobial chemotherapy is of paramount impoance to reduce morbidity and moality associated with sepsis. Inflammatory markers currently in use, such as C-reactive protein (CRP) do not reliably differentiate between the systemic inflammatory response and sepsis. Procalcitonin (PCT), a precursor of calcitonin, is a 116 amino acid protein that has been proposed as a marker of disease severity in conditions such as septicaemia, meningitis, pneumonia, urinary tract infection (UTI) and fungal and parasitic infection. Ref :