Effects of thyroid hormone withdrawal on natriuretic peptides during radioactive iodine therapy in female patients with differentiated thyroid cancer.
OBJECTIVE
We aimed to investigate the effects of thyroid hormone withdrawal on N-terminal prohormone forms of atrial natriuretic peptide (NT-proANP) and brain natriuretic peptide (NT-proBNP) during radioiodine therapy in female patients with differentiated thyroid cancer (DTC).


METHODS
Serum concentrations of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), NT-proANP and NT-proBNP were measured in 51 female patients with DTC (48.7 ± 4.2 years) at three time-points: day of radioiodine therapy (t1 - under acute hypothyroidism), 5 days after radioiodine (t2 - under acute hypothyroidism) and 3 months after radioiodine (t3 - under TSH suppression). Thirty healthy euthyroid women served as controls (42.8 ± 5.6 years).


RESULTS
At t1/t2/t3, median NT-proANP was 5.2/1.7/487 pmol/L vs. 297.7 pmol/L in control group (p < 0.001), median NT-proBNP was 50.1/36.5/79.5 pmol/L vs. 64.5 pmol/L (p < 0.001) and median NT-proANP/NT-proBNP ratios was 0.20/0.18/4.81 vs. 4.14 (p < 0.001). In acute hypothyroidism, FT3 levels were positively correlated with NT-proANP (r = 0.38, p = 0.005), NT-proANP/NT-proBNP ratios (r = 0.47, p = 0.001), heart rate (r = 0.39, p = 0.005), and negatively with mean arterial blood pressure (r = -0.58, p < 0.001).


CONCLUSIONS
Our results indicate that NT-proANP reflects more accurately direct thyroid hormone effects than NT-proBNP. Thyroid hormone-dependent hemodynamic effects seem to be overlapped on the direct stimulatory effect of thyroid hormones on NT-proANP secretion by cardiac myocytes.
a Department of Carcinogenesis and Molecular Biology , Institute of Oncology Bucharest , Bucharest , Romania.
Adina Elena
AE
Stanciu
b Department of Nuclear Medicine , Institute of Oncology Bucharest , Bucharest , Romania.
Anca Elena
AE
Hurduc
c Department of Electrical Engineering Faculty , University "Politehnica" of Bucharest , Bucharest , Romania.
Marcel Marian
MM
Stanciu
D000328:Adult; D000368:Aged; D009320:Atrial Natriuretic Factor / Q000097:blood*; D016022:Case-Control Studies; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007037:Hypothyroidism; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D011498:Protein Precursors / Q000097:blood; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013964:Thyroid Neoplasms / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D013972:Thyrotropin / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
D007457:Iodine Radioisotopes; D011498:Protein Precursors; D014284:Triiodothyronine; D020097:Natriuretic Peptide, Brain; D009320:Atrial Natriuretic Factor; D013972:Thyrotropin
Amino acids; blood pressure; cardiac pumping; oncology; peptides and proteins; thyroid diagnostics and treatment; thyroid hormones