title: Pro-A-type and N-terminal pro-B-type natriuretic peptides in different thyroid function states.
abstract: OBJECTIVE
  Natriuretic peptides are produced predominantly in the heart and secreted in response to volume expansion and pressure overload. A wide spectrum of cardiac changes is observed in thyroid dysfunctions. This study investigates mid regional pro A-type (proANP) and N-terminal pro-B-type natriuretic peptide (NTproBNP) levels in different thyroid states and evaluates the effect of L-thyroxine treatment on natriuretic peptides in patients with subclinical hypothyroidism.
  
  
  METHODS
  Case-control and double-blind, placebo-controlled trial. Sera from 161 female patients (35 with overt, 63 with subclinical hypothyroidism; 10 with overt, 14 with subclinical hyperthyroidism; 40 euthyroid controls) were analysed. ProANP and NT-proBNP were measured at baseline and 48 weeks after L-thyroxine treatment in subclinical hypothyroidism.
  
  
  RESULTS
  Circulating proANP and NT-proBNP levels were higher in hyperthyroid patients than in hypothyroid and euthyroid patients (p <0.001). Plasma proANP levels tended to be lower in overt hypothyroidism than in subclinical hypothyroidism. ProANP and NT-proBNP levels correlated weakly to thyroid stimulating hormone (TSH) (r = -0.3 and -0.2, respectively). The natriuretic peptide levels of subclinical and overt hypothyroid subjects showed no difference with those of euthyroid subjects. L-thyroxine treatment had no effect on natriuretic peptide levels in subclinical hypothyroidism.
  
  
  CONCLUSIONS
  Natriuretic peptide levels are altered in different thyroid states with a more pronounced effect in hyperthyroidism than in hypothyroidism. Hyperthyroidism should be considered in patients presenting with unclear symptoms and mildly elevated natriuretic peptide levels, as overt hyperthyroidism results in increased serum A- and B-type natriurectic peptide levels, typically seen in mild heart failure.
authors.affiliation: Department of Endocrinology, University Hospital Basel, Switzerland. christmj@bluewin.ch
authors.forename: M
authors.initials: M
authors.lastname: Christ-Crain
authors.forename: N G
authors.initials: NG
authors.lastname: Morgenthaler
authors.forename: C
authors.initials: C
authors.lastname: Meier
authors.forename: C
authors.initials: C
authors.lastname: Müller
authors.forename: C
authors.initials: C
authors.lastname: Nussbaumer
authors.forename: A
authors.initials: A
authors.lastname: Bergmann
authors.forename: J J
authors.initials: JJ
authors.lastname: Staub
authors.forename: B
authors.initials: B
authors.lastname: Müller
mesh_terms: D009320:Atrial Natriuretic Factor / Q000097:blood*; D016022:Case-Control Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood* / Q000378:metabolism; D007037:Hypothyroidism / Q000097:blood* / Q000378:metabolism; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D013960:Thyroid Function Tests
chemical_list: D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain; D009320:Atrial Natriuretic Factor