title: Vitamin D deficiency in patients with erythropoietic protoporphyria.
abstract: BACKGROUND
  The main symptom of patients with erythropoietic protoporphyria (EPP) is painful photosensitivity, starting within minutes of sun exposure and leading to sun-avoidance. As 80-100% of vitamin D is synthesized under the influence of sunlight, we investigated whether the avoidance of sunlight exposure in the Dutch EPP patient population causes vitamin D deficiency. Furthermore, we studied the relation between vitamin D levels, total erythrocyte protoporphyrin and quality of life.
  
  
  METHODS
  In a cross-sectional study of 48 Dutch EPP patients (mean age 41.4 years; range 16-77; 23 male, 25 female), we assessed serum 25-hydroxyvitamin D (25(OH)D) levels between June and November 2007, as well as total erythrocyte protoporphyrin (TEP) levels and Dermatology Life Quality Index (DLQI) scores.
  
  
  RESULTS
  Mean serum 25(OH)D was 66 nmol/L (range 18-140, quartiles 36, 87). Twenty-two patients (46%; 15 male, 7 female) were vitamin D deficient. There was a significant difference (p = 0.029) in mean serum 25(OH)D between female (mean 75 nmol/L, range 18-140) and male patients (mean 55 nmol/L, range 18-115). The level of serum 25(OH)D showed a negative correlation with total erythrocyte protoporphyrin (TEP) (Pearson rank correlation (r(p)) = -0.337; p = 0.034). Serum 25(OH)D was inversely associated with scores of the Dermatology Life Quality Index (DLQI) (Spearman's rho correlation (r(s)) = -0.486; p = 0.001).
  
  
  CONCLUSIONS
  The prevalence of vitamin D deficiency is high in the Dutch EPP population, especially in male patients, and correlates with the severity of EPP. Screening for and treatment of vitamin D deficiency should therefore be implemented in the care of these patients.
authors.affiliation: Department of Internal Medicine, Section of Vascular Pharmacology and Metabolic Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: J M C
authors.initials: JM
authors.lastname: Spelt
authors.forename: F W M
authors.initials: FW
authors.lastname: de Rooij
authors.forename: J H P
authors.initials: JH
authors.lastname: Wilson
authors.forename: A A  M
authors.initials: AA
authors.lastname: Zandbergen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D017092:Porphyria, Erythropoietic / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D015995:Prevalence; D011524:Protoporphyrins / Q000097:blood; D011788:Quality of Life; D012307:Risk Factors; D012737:Sex Factors; D013472:Sunlight / Q000009:adverse effects*; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D011524:Protoporphyrins; D014807:Vitamin D; C104450:25-hydroxyvitamin D