title: Interpretation of vitamin A status in apparently healthy Pakistani children by using markers of subclinical infection.
abstract: BACKGROUND
  Plasma retinol concentrations are depressed by infection but are commonly used to assess vitamin A status.
  
  
  OBJECTIVE
  We measured 2 acute phase proteins, alpha(1)-antichymotrypsin (ACT) and alpha(1)-acid glycoprotein (AGP), to determine whether they could be used to assist in interpreting vitamin A status.
  
  
  METHODS
  In 1997, a 2-stage cluster-sampling procedure was used to select 3074 apparently healthy, 6-60-mo-old children from rural and urban areas of North West Frontier Province, Pakistan. Plasma retinol, ACT, AGP, and ferritin measurements and anthropometric measurements were obtained for 2519 children.
  
  
  RESULTS
  Median plasma retinol, ACT, AGP, and ferritin concentrations were 0.86 micromol/L, 0.39 g/L, 1.14 g/L, and 5.5 microg/L, respectively. There were no significant (P: > 0.05) differences in retinol, ACT, or AGP by sex or age. Some 797 children (32%) had retinol concentrations <0.7 micromol/L and 87 (4%) had retinol concentrations <0.35 micromol/L; 274 children (11%) had elevated ACT (>0.6 g/L) and 1141 (45%) had elevated AGP (>1.2 g/L). Retinol concentration correlated with ACT (r = -0.141), AGP (r = -0.138), and ferritin (r = -0.09) (all P: < 0.001), but stepwise multiple regression indicated that these 3 variables made a minimal although quantifiable contribution to the variance of retinol (ACT, r(2) = 0.02; all 3 variables, r(2) = 0.03).
  
  
  CONCLUSIONS
  The transient depression in plasma retinol produced by subclinical infection increased the number of at-risk children by 10% (76 of 797) and 56% (49 of 87) for plasma retinol concentrations <0.7 and <0.35 micromol/L, respectively. In addition, dietary inadequacy may be responsible for retinol concentrations being approximately 16% lower in Pakistani children than in children in the United Kingdom, where dietary vitamin A is adequate.
authors.affiliation: Department of Nutrition, Agricultural University and Goverment Department of Health, Peshawar, North West Frontier Province, Pakistan.
authors.forename: P I
authors.initials: PI
authors.lastname: Paracha
authors.forename: A
authors.initials: A
authors.lastname: Jamil
authors.forename: C A
authors.initials: CA
authors.lastname: Northrop-Clewes
authors.forename: D I
authors.initials: DI
authors.lastname: Thurnham
mesh_terms: D015415:Biomarkers / Q000097:blood*; D002675:Child, Preschool; D005260:Female; D005293:Ferritins / Q000097:blood; D006801:Humans; D007223:Infant; D007239:Infections / Q000097:blood*; D008297:Male; D009752:Nutritional Status; D009961:Orosomucoid / Q000032:analysis; D010154:Pakistan; D014801:Vitamin A / Q000097:blood; D014802:Vitamin A Deficiency / Q000175:diagnosis; D000514:alpha 1-Antichymotrypsin / Q000097:blood
chemical_list: D015415:Biomarkers; D009961:Orosomucoid; D000514:alpha 1-Antichymotrypsin; D014801:Vitamin A; D005293:Ferritins