title: Complementary Serologic Investigations in Children with Celiac Disease Is Unnecessary during Follow-Up.
abstract: OBJECTIVE
  To determine the frequency of nutritional deficiencies and thyroid dysfunction in children with celiac disease (CD) and during follow-up after initiation of a gluten-free diet. Laboratory investigations of hemoglobin, ferritin, calcium, folate, vitamin B12, vitamin D, and thyroid function are regularly ordered in children with CD despite sufficient evidence for these.
  
  
  METHODS
  Between 2009 and 2014, test results of hemoglobin, ferritin, folate, vitamin B12, calcium, vitamin D (25[OH]D), free thyroxin, and thyroid stimulating hormone of children with CD regularly seen at the Leiden University Medical Center were investigated. Laboratory reference ranges were used to define abnormal results. Pearson χ(2) test for trend, unpaired t test, and 1-way ANOVA were used for statistical analysis.
  
  
  RESULTS
  Of the 182 children evaluated, 119 were newly diagnosed. On average, 17% of results per year were missing because of incomplete blood investigations. Iron deficiency (28%) and iron deficiency anemia (9%) were found at the time of diagnosis of CD. Folate (14%), vitamin B12 (1%), and vitamin D deficiencies (27%) were also seen. No hypocalcemia or thyroid dysfunction was found. At follow-up, iron deficiency, iron deficiency anemia, and folate and vitamin D deficiency were observed in 8%, 2%, 3%, and 25% of patients, respectively. Vitamin B12 deficiency, hypocalcemia, and thyroid disease were not found.
  
  
  CONCLUSIONS
  Complementary blood investigations are relevant at the time of diagnosis of CD but have little diagnostic yield during follow-up visits once the patient is placed on a gluten-free diet. Thus, we recommend that these variables only be assessed on indication, such as fatigue or abnormal growth.
authors.affiliation: Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: m.m.s.wessels@lumc.nl.
authors.forename: Margaretha Maria Susanna
authors.initials: MM
authors.lastname: Wessels
authors.affiliation: Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Iris I
authors.initials: II
authors.lastname: van Veen
authors.affiliation: Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Sabine Lisa
authors.initials: SL
authors.lastname: Vriezinga
authors.affiliation: Department of Statistics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Hein
authors.initials: H
authors.lastname: Putter
authors.affiliation: Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands; Department of Pediatrics, Erasmus University Medical Center, Sophia Children's Hospital, Rotterdam, The Netherlands.
authors.forename: Edmond Henri Herman Maria
authors.initials: EH
authors.lastname: Rings
authors.affiliation: Department of Pediatrics, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Mearin
mesh_terms: D000293:Adolescent; D002446:Celiac Disease / Q000097:blood* / Q000150:complications / Q000178:diet therapy*; D002648:Child; D055050:Diet, Gluten-Free; D005260:Female; D005500:Follow-Up Studies; D006403:Hematologic Tests / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D044342:Malnutrition / Q000097:blood / Q000175:diagnosis / Q000209:etiology; D012189:Retrospective Studies; D013959:Thyroid Diseases / Q000097:blood / Q000175:diagnosis / Q000209:etiology; D019564:Unnecessary Procedures