title: Hypophosphatemia in Critically Ill Children: Risk Factors, Outcome and Mechanism.
abstract: OBJECTIVE
  To determine the prevalence of hypophosphatemia in critically ill children and its association with clinical outcomes; to determine risk factors and mechanism of hypophosphatemia.
  
  
  METHODS
  Levels of serum phosphate, phosphate intake, renal phosphate handling indices and blood gases were measured on days 1, 3, 7 and 10 of pediatric intensive care unit (PICU) stay. Hypophosphatemia was defined as any serum phosphorus <3.8 mg/dl for children younger than 2 y and <3.5 mg/dl for children 2 y or older. Renal phosphate loss was assessed using the ratio of tubular maximum reabsorption of phosphate (TmP) to glomerular filtration rate (GFR) [TmP/GFR].
  
  
  RESULTS
  Prevalence of hypophosphatemia was 71.6 % (95 % CI: 64.6-78.6). On adjusted analysis, hypophosphatemia was associated with prolonged PICU length of stay (PICU LOS > 6 d) (adjusted OR: 3.0 [95 % CI: 1.4-6.7; p = 0.005]) but not associated with increased mortality. Renal phosphate threshold was significantly lower on all the days in hypophosphatemic group compared to that of non-hypophosphatemic group. No statistically significant difference in the amount of phosphate intake was seen in both the groups.
  
  
  CONCLUSIONS
  Hypophosphatemia is highly prevalent in critically ill children and is associated with prolonged PICU LOS. Increased phosphate loss in urine is one of the mechanism responsible for hypophosphatemia in critically ill children.
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India.
authors.forename: Satish Kumar
authors.initials: SK
authors.lastname: Shah
authors.affiliation: Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Irshad
authors.affiliation: Department of Endocrinology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Nandita
authors.initials: N
authors.lastname: Gupta
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India.
authors.forename: Sushil Kumar
authors.initials: SK
authors.lastname: Kabra
authors.affiliation: Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India. rakesh_lodha@hotmail.com.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Lodha
mesh_terms: D002648:Child; D016638:Critical Illness; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D017674:Hypophosphatemia; D015278:Intensive Care Units, Pediatric; D008297:Male; D012307:Risk Factors
keywords: Children; Critical illness; Hypophosphatemia; Length of stay; Outcomes; Phosphaturia