title: Threshold levels of 25-hydroxyvitamin D and parathyroid hormone for impaired bone health in children with congenital ichthyosis and type IV and V skin.
abstract: BACKGROUND
  Patients with congenital ichthyosis, especially those with darker skin types, are at increased risk of developing vitamin D deficiency and rickets. The relationships between 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH) and bone health have not been studied previously, in ichthyosis.
  
  
  OBJECTIVE
  To determine the threshold levels of 25(OH)D and PTH for impaired bone health in children with congenital ichthyosis.
  
  
  METHODS
  In this cross-sectional study, 119 children with ichthyosis and 168 controls were recruited. Serum 25(OH)D, PTH, calcium, phosphate and alkaline phosphatase (ALP) were measured. Radiological screening for rickets was carried out only in children with ichthyosis.
  
  
  RESULTS
  Forty-seven children with ichthyosis had either clinical or radiological evidence of rickets. The correlation between serum 25(OH)D and PTH showed that a serum level of 25(OH)D 8 ng mL(-1) was associated with a significant increase in PTH. The correlation between PTH and ALP showed that a serum PTH level of 75 pg mL(-1) was associated with a significant increase in ALP levels. Of the different clinical phenotypes of ichthyosis, both autosomal recessive congenital ichthyosis (ARCI) and epidermolytic ichthyosis (EI) were found to have significantly increased PTH, ALP and radiological rickets scores compared with common ichthyosis.
  
  
  CONCLUSIONS
  Serum levels of 25(OH)D ≤ 8 ng mL(-1) and PTH ≥ 75 pg mL(-1) significantly increases the risk for development of rickets [odds ratio (OR) 2·8; 95% confidence interval (CI) 1·05-7·40; P = 0·04] in ichthyosis. Among the different types, patients with ARCI (OR 4·83; 95% CI 1·74-13·45; P < 0·01) and EI (OR 5·71; 95% CI 1·74-18·79; P < 0·01) are at an increased risk of developing rickets.
authors.affiliation: Department of Dermatology, All India Institute of Medical Sciences, New Delhi, 110029, India.
authors.forename: G
authors.initials: G
authors.lastname: Sethuraman
authors.forename: V
authors.initials: V
authors.lastname: Sreenivas
authors.forename: V K
authors.initials: VK
authors.lastname: Yenamandra
authors.forename: N
authors.initials: N
authors.lastname: Gupta
authors.forename: V K
authors.initials: VK
authors.lastname: Sharma
authors.forename: R K
authors.initials: RK
authors.lastname: Marwaha
authors.forename: N
authors.initials: N
authors.lastname: Bhari
authors.forename: M
authors.initials: M
authors.lastname: Irshad
authors.forename: M
authors.initials: M
authors.lastname: Kabra
authors.forename: S
authors.initials: S
authors.lastname: Thulkar
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000150:complications; D017490:Ichthyosis, Lamellar / Q000097:blood / Q000150:complications*; D007223:Infant; D008297:Male; D010281:Parathyroid Hormone / Q000378:metabolism*; D012279:Rickets / Q000097:blood / Q000209:etiology*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D