title: Thyroid cysts: a new extra-adrenal site of aldosterone synthase expression and increased aldosterone content.
abstract: BACKGROUND
  The rapid re-accumulation of fluid following aspiration of thyroid cystic lesions suggests that active transport of sodium and water may be involved in volume regulation of these lesions. In this study we address the possibility that aldosterone may take part in this process.
  
  
  METHODS
  Thirty-one patients (29 women and two men), with a mean age of 52.7 +/- 13.2 years (range: 27-77 years) underwent evaluation for thyroid nodules that had a sonographic cystic component. Cystic fluid obtained by FNA biopsy was sent for cytological examination and biochemical measurements. In 10 patients, material was collected for RNA extraction and determination of aldosterone synthase expression by RT-PCR amplification.
  
  
  RESULTS
  All lesions were benign, cystic, colloid nodules. Cyst fluid aldosterone levels as measured by routine radioimmunoassay (RIA) were elevated above the normal plasma levels in all but five patients. Mean aldosterone levels were 27.1 +/- 22.9 ng/dl (SD) (range: 5.9-117.5 ng/dl). In contrast, cyst cortisol values were in the low, low normal serum range (6.2 +/- 2.9 microg/dl, range: 0.2-10.2 microg/dl). Sodium, chloride and potassium levels were 137 +/- 4.7 mEq/l, 98 +/- 5 mEq/l and 4.9 +/- 1.4 mEq/l, respectively. Plasma aldosterone levels were normal in all patients tested. To confirm these results, 12 samples were assayed after extraction and chromatography using a highly specific antibody. Cyst aldosterone levels in this group were elevated above the normal serum range in all but one patient (mean concentration: 24.5 +/- 14.6 ng/dl, range: 8.72-40.1 ng/dl). In this group, 18(OH)B levels were within the normal plasma range (12-55 ng/dl) in all but one patient (34.9 +/- 17 ng/dl). Furthermore, aldosterone synthase mRNA expression was found in aspirates of four of 10 patients.
  
  
  CONCLUSIONS
  The increased aldosterone concentration and the presence of aldosterone synthase expression suggest that aldosterone may be locally produced and secreted in thyroid tissue. The pathophysiological implications of this finding remain to be established.
authors: Institute of Endocrinology, Metabolism and Hypertension, Tel Aviv - Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel.
authors: Yona
authors: Y
authors: Greenman
authors: Yana
authors: Y
authors: Trostanetsky
authors: Sarit
authors: S
authors: Ben-Shemen
authors: Nili
authors: N
authors: Grazas
authors: Rona
authors: R
authors: Limor
authors: Etty
authors: E
authors: Osher
authors: Sabina
authors: S
authors: Lewicka
authors: Paul
authors: P
authors: Vecsei
authors: Naftali
authors: N
authors: Stern
mesh_terms: D000328:Adult; D000368:Aged; D000450:Aldosterone / Q000032:analysis / Q000378:metabolism*; D001707:Biopsy, Needle; D002712:Chlorides / Q000097:blood; D003560:Cysts / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D019405:Cytochrome P-450 CYP11B2 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis / Q000097:blood; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood; D012313:RNA / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012964:Sodium / Q000097:blood; D016606:Thyroid Nodule / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism
chemical_list: D002712:Chlorides; D000450:Aldosterone; D012313:RNA; D012964:Sodium; D019405:Cytochrome P-450 CYP11B2; D011188:Potassium; D006854:Hydrocortisone