Background: Malnutrition affects 50% of hospitalized children and 25-70% of the critically 
ill children. It increases the incidence of complications and mortality. Malnutrition is 
associated with an altered metabolism of certain substrates, increased metabolism and 
catabolism depending on the severity of the lesion, and reduced nutrient delivery. also,.
Vitamin D is essential for bone health, as well as for cardiovascular and immune function. In 
critically ill adults vitamin D deficiency (VDD) is common, and is associated with sepsis and 
higher critical illness severity. Objectives: Aim of the study: to determine the effect of 
malnutrition on mortality in Pediatric Intensive Care Unit (PICU) and neonatal intensive care 
unit in minia university hospital. Methods: This was a prospective study done over 6 month. 
There were total 220 patients (1 month to18 years), who were divided into cases with weight 
for age <3 (rd) centile and controls with ≥3(rd) centile of WHO charts. Cases were 
subdivided into mild/moderate (61-80% of expected weight for age) and severe malnutrition 
(<60%).. Blood was collected on admission to PICU and analyzed for 25-OH-D levels. The 
three groups: were subjected to complete history taking, through clinical examination and 
laboratory investigations including determining serum vitamin D level. Results: Out of total, 
48% patients were underweight, and malnutrition was more in early childhood (P - 0.01) and 
were more deficient in serum vitamin D level (p 0.0001) Cases needed prolonged mechanical 
ventilation (P - 0.0001) and hospital stay (P - 0.0001) compared to controls. mortality was 
significantly higher in severely malnourished (P value 0.0001). The prevalence of VDD was 
associated with prolonged stay in intensive care unit (P0.0001), mechanical ventilation (p 
0.005) . Conclusion: Severe malnutrition and vitamin D deficiency at PICU admission was 
prevalent in critically ill children and was associated with adverse clinical outcomes.