Vitamin D deficiency is highly prevalent in critically ill adult and pediatric population that causes multiple adverse health outcomes including higher illness severity score, increased morbidity and mortality, multiple organ dysfunction, longer duration of Mechanical ventilation, longer duration of Oxygen therapy and increased length of stay (LOS) in PICU and hospital. Vitamin D deficiency is a modifiable risk factor that can be corrected with high dose of vitamin D supplementation to improve the clinical outcome.

This study is designed to determine whether random vitamin D supplementation within dose limits improves clinical outcomes in critically ill children.

Vitamin D is known for its role in bone metabolism and calcium haemostasis but it is also required for the optimal functioning of cardiovascular and innate immune systems.

As a pleiotropic hormone it has been increasingly implicated in proper functioning of multiple organs; its deficiency is associated with cardiovascular diseases, asthma, cancer, multiple sclerosis, diabetes and acute lower respiratory tract infections. Over one billion people are vitamin D deficient worldwide and in Pakistani population vitamin D deficiency is reported as high as 76% despite abundant sunshine.

Beside of ambulatory individuals, the patients presenting in intensive care units are also found Vitamin D deficient. In adult intensive care settings studies have shown vitamin D deficiency (VDD) present in 60% of critically ill adult patients.VDD is also very common in pediatric intensive care units (PICU) worldwide, ranging from 30 to 80%.

Although there is high prevalence of VDD in pediatric and adult population, but there is no uniform definition of VDD exists. Levels of active metabolite 1,25(OH)2D of Vitamin D at tissue level cannot be measured, however, patient's blood level of 25-hydroxy vitamin D is used to know vitamin D stores in the body. Patient with serum vitamin D level<20ng/ml is considered to be vitamin D deficient.

VDD is associated with clinically poor outcomes like increased duration of mechanical ventilation, increased length of hospital stay, Sepsis, Acute respiratory failure and mortality in critically ill patients.

The existing evidences suggest that Vitamin D3 supplementation enhances recovery from influenza, recurrent pneumonias and tuberculosis. Recently, an observational study of adult patients suggested that patients with VDD showed decrease in the odds of all cause-mortality when their Vitamin D status was improved before hospitalization.

A randomized study demonstrated that one time bolus dose of oral vitamin D supplementation caused decrease in mortality in a group of patients with severe VDD.

A significant literature is available that suggests vitamin D deficiency as a modifiable risk factor in PICU settings. The recognized importance of vitamin D to the health of multiple organ systems suggest that rapid normalization could represent a simple, inexpensive, and safe means of improving outcomes and reducing health care spending.

This study is designed to supplement large dose of vitamin D that may lead to fast correction of low vitamin D level in critically ill children and possibility of better clinical outcome. If such an association is established by this study, routine detection and use of Vitamin D might be recommended for critically ill children admitted to PICU.

Inclusion Criteria:

• Children of age 6 months to 10 years, either gender admitted in ICU for critical illness (on medical record) with PIM-2 score suggesting probability of mortality more than 50%.

Exclusion Criteria:

• Children with known adrenal, pituitary, hypothalamic or thyroid disease.
• Those who have complex congenital defects.
• Moribund at time of admission.
• Those who were expected to be care withdrawn.
• Patients who had received large dose regimen (200,000 IU or more) of vitamin D during the previous three months before admission.