El péptido auricular natriurético en las disfunciones tiroideas

Abstract

Thyroid dysfunction is commonly associated with significant changes in atrial natriuretic peptide (ANP) concentrations. Thus, hyperthyroid patients show high ANP values, but information in regards to ANP levels in hypothyroid patiens is yet not clear. In order to investigate whether thyroid hormones, and specially triiodotironine (T3), exert a physiological role on ANP modulation, we have studied a group of 7 normal males aged 21.5 ± 0.9 years (range 20 to 30) in basal conditions and after treatment with iopanic acid (IA), a 5'desiodase blocker, at daily dosis of 3 gr. for three days. Additionally we determined features of the effect of hypothyroidism and hyperthyroidism on ANP secretion in 10 hypothyroid patients aged 45.8 ± 3.5 years (range 32-58), and 10 patients with hyperthyroidism aged 40.4 ± 3.75 years (range 25-49).

A treatment induced a significant reduction of free T3 (1.8 ± 0.07 vs 2.63 ± 0.12 pg/mL p< 0.001), after three days of treatment with respect to basal values, whereas a clear rise in reverse T3 (0.52 ± 0.07 vs 0.18 ± 0.02 nmol/L p< 0.001) and Free T4 (1.66 ± 0.11 vs 1.3 ± 0.07 ng/dL p< 0.01) was observed. T4 total (131 ± 5.53 vs 109 ± 5.9 nmol/L p< 0.05) and TSH (5.52 ± 0.5 vs 1.76 ± 0.21 mU/L p< 0.0001) raised steadily after the third day of treatment reaching subclinical hypothyroid condition, indicating an effective blockade of 5'desiodase.

There was no evidence of differences in ANP levels after treatment with IA (day 1: 49.7 ± 5.45 pg/mL; day 2: 50.3 ± 4.84 pg/mL: day 3: 53.6 ± 7.36 pg/ mL) with respect to those observed in basal state (47.3 ±4.14 pg/mL). ANP levels were higher in hyperthyroid patients (252.2 ± 36.4 pg/mL) with respect to those observed in hypothyroid patients (70.6 ± 9.3 pg/mL. p<0.005) and normal (47.3 ± 4.14 pg/mL p<0.001).

These results show that neither selective T3 reduction nor the hypothyroidism induce variation in ANP levels, suggesting that ANP variations observed in states of thyroid disease may be related to situations characterized by severe and long lasting hyper o hyposecretion of thyroid hormones. The influence of haemodinamic alterations on ANP secretion can not be ruled out. Therefore, these findings are not in favour of a physiological role of T3 on ANP secretion.