The higher rate of vitamin D deficiency is spotted among patients being hospitalized or in critical condition. Especially, vitamin D level below normal prolongs hospital stay and increases incidence of adverse prognosis and pushing up mortality of a number of diseases. However, it is remain unclear the relationship between vitamin D levels and critically ill, especially infection or sepsis. In this study, the investigators evaluate the significance of vitamin D for diagnosis and other relevant assessments of ICU cases, including vitamin D's relevance to sepsis, as well as its value in severity and prognosis assessment, high-performance liquid chromatography and tandem mass spectrometry was used to detect the quantification of the total 25(OH)D in serum of critically ill patients. The investigators speculate that measurement of vitamin D could be taken as an indicator for diagnosis and assessment in critically ill patients.

Inclusion Criteria:

• Male and female aged 18 years old and over;

• Entered ICU;

• Fulfilled at least two criteria of systemic inflammatory response syndrome

  • core temperature higher than 38 °C or lower than 36 °C
  • respiratory rate above 20/min, or PCO2 below 32 mmHg
  • pulse rate above 90/min, and
  • white blood cell count greater than 12,000/μl or lower than < 4,000/μl or less than 10% of bands.

Exclusion Criteria:

• patients or their relatives refused

All the subjects were selected from among inpatients who were hospitalized between October-December, 2011 in the Surgical ICU, Respiratory ICU, and Emergency ICU, Chinese PLA General Hospital.