title: CONGENITAL ADRENAL HYPERPLASIA DUE TO 21-HYDROXYLASE DEFICIENCY PRESENTING AS ADRENAL INCIDENTALOMA: A SYSTEMATIC REVIEW AND META-ANALYSIS.
abstract: OBJECTIVE
  Adrenal incidentalomas (AIs) may be due to congenital adrenal hyperplasia (CAH) due to homozygous CYP21A2 mutations, or perhaps from heterozygous carrier status. It is unclear if genetic or biochemical testing of CYP21A2 status in AI is justified, despite its potential for avoiding adrenal crises in those referred for adrenalectomy.
  
  
  METHODS
  We systematically searched PubMed/MEDLINE for articles published up to October 19, 2015 containing all terms associated with adrenal tumors and CAH. Meta-analyses were used to estimate the CAH or carrier prevalence in AI and assess clinical factors that may guide testing.
  
  
  RESULTS
  Thirty-six publications were included. Of AI patients biochemically screened for CAH, 58/990 (5.9%) were diagnosed with CAH. Genetic screening of all AIs revealed only 2/252 (0.8%) with clear CAH. The carrier prevalence was 10.2% (36/352). The rate of 0.8% (8/1,000) genetically confirmed CAH is higher than the 1/15,000 affected by classic CAH or 1/1,000 by nonclassic CAH in the Caucasian population. The rate of heterozygous CYP21A2 mutation frequency is similar to those in reported in population studies. Levels of both basal and stimulated 17-hydroxyprogesterone positively correlated with AI diameter. Although bilateral incidentalomata were frequent in CAH, their presence did not predict CYP21A2 status.
  
  
  CONCLUSIONS
  The presence of an AI does not increase the probability of detection of CAH or CYP21A2 carrier status to the extent routine genetic testing is justified. Screening with 17-hydroxyprogesterone levels appears to lack specificity in the setting of an AI. CYP21A2 mutation analysis is probably the only reliable method for CAH diagnosis in AIs.
  
  
  BACKGROUND
  ACC = adrenocortical carcinoma ACTH = adrenocorticotropic hormone AI = adrenal incidentaloma CAH = congenital adrenal hyperplasia NCAH = nonclassic congenital adrenal hyperplasia 17OHP = 17-hydroxyprogesterone SV = simple virilizing.
authors.forename: Henrik
authors.initials: H
authors.lastname: Falhammar
authors.forename: David J
authors.initials: DJ
authors.lastname: Torpy