title: Urea, Uric Acid, Prolactin and fT4 Concentrations in Aqueous Humor of Keratoconus Patients.
abstract: Keratoconus is a noninflammatory disease of the cornea associated with progressive thinning and conical shape. Metabolic alterations in the urea cycle, with changes in collagen fibril stability, oxidative stress, thyroid hormones and prolactin with regulatory effect on biosynthesis and biomechanical stability of corneal stroma, may all play a role in keratoconus etiology. Our purpose was to determine urea, uric acid, prolactin and free thyroxin (fT4) concentrations in human aqueous humor (hAH) of keratoconus and cataract patients.
  
  
  
  hAH was collected from 100 keratoconus (penetrating keratoplasty) (41.9 ± 14.9 years, 69 males) and 100 cataract patients (cataract surgery) (71.2 ± 12.4 years, 58 males). Urea, uric acid, prolactin and fT4 concentrations were measured by Siemens clinical chemistry or immunoassay system. For statistical analysis, a generalized linear model (GLM) was used.
  
  
  
  Urea concentration was 11.88 ± 3.03 mg/dl in keratoconus and 16.44 ± 6.40 mg/dl in cataract patients, uric acid 2.04 ± 0.59 mg/dl in keratoconus and 2.18 ± 0.73 mg/dl in cataract groups. Prolactin concentration was 3.18 ± 0.34 ng/ml in keratoconus and 3.33 ± 0.32 ng/ml in cataract patients, fT4 20.57 ± 4.76 pmol/l in KC and 19.06 ± 3.86 pmol/l in cataract group. Urea concentration was effected through gender (p = 0.039), age (p = 0.001) and diagnosis (p = 0.025). Uric acid concentration was not effected through any of the analyzed parameters (p > 0.056). Prolactin and fT4 concentration were effected only through diagnosis (p = 0.009 and p = 0.006).
  
  
  
  Urea and prolactin concentrations are decreased, fT4 concentration is increased in aqueous humor of keratoconus patients, and uric acid concentration remains unchanged. Urea concentration in aqueous humor is also increased in older and male patients. Therefore, metabolic disorder and hormonal balance may both have an impact on keratoconus development. Further studies are necessary to assess the specific impact.
authors.affiliation: a Department of Ophthalmology , Saarland University Medical Center , Homburg/Saar , Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Stachon
authors.affiliation: b Westpfalz-Klinikum GmbH, Institute for Laboratory Medicine , Kaiserslautern , Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Stachon
authors.affiliation: b Westpfalz-Klinikum GmbH, Institute for Laboratory Medicine , Kaiserslautern , Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Hartmann
authors.affiliation: a Department of Ophthalmology , Saarland University Medical Center , Homburg/Saar , Germany.
authors.forename: Berthold
authors.initials: B
authors.lastname: Seitz
authors.affiliation: c Experimental Ophthalmology , Saarland University , Homburg/Saar , Germany.
authors.forename: Achim
authors.initials: A
authors.lastname: Langenbucher
authors.affiliation: a Department of Ophthalmology , Saarland University Medical Center , Homburg/Saar , Germany.|d Department of Ophthalmology , Semmelweis University , Budapest , Hungary.
authors.forename: Nóra
authors.initials: N
authors.lastname: Szentmáry
mesh_terms: D000328:Adult; D000368:Aged; D001082:Aqueous Humor / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006801:Humans; D007118:Immunoassay; D007640:Keratoconus / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011388:Prolactin / Q000378:metabolism*; D013974:Thyroxine / Q000378:metabolism*; D014508:Urea / Q000378:metabolism*; D014527:Uric Acid / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D014527:Uric Acid; D014508:Urea; D011388:Prolactin; D013974:Thyroxine
keywords: Aqueous humor; fT4; keratoconus; prolactin; urea; uric acid