Absorption of thyroxine is decreased in
patients with gastric inflammation and by omeprazole therapy
(July 2006)
The background of the study. The absorption of
thyroxine (T4) may be decreased in patients with gastrointestinal
disorders and by drugs. In this study, the effect of Helicobacter
pylori–related gastric inflammation (gastritis), gastric
atrophy, and omeprazole on T4 absorption was determined.
How the study was done. The study subjects were
248 patients treated with T4 to reduce the size of a goiter. The
T4 was given in doses that reduced their serum thyrotropin (TSH)
concentrations to 0.05 to 0.2 mU/L (normal, 0.2 to 4.0). While taking
T4, 113 had findings suggestive of decreased gastric acid secretion.
They included 53 patients with H. pylori gastritis and
60 patients with gastric atrophy. The dose of T4 needed to maintain
serum TSH concentrations between 0.05 to 0.2 mU/L in these 113 patients
was compared with the dose needed in 135 patients with no gastrointestinal
disorders (reference group).
In addition, 11 patients with goiter who were treated with T4 were
studied before and at the time of diagnosis, and after successful
therapy for H. pylori infection, and 10 patients with goiter
who were treated with T4 were studied before and during long-term
therapy with omeprazole (which blocks gastric acid secretion) for
gastroesophageal reflux disease.
The results of the study. The doses of T4 needed
to maintain serum TSH concentrations between 0.05 and 0.2 mU/L in
the patients with H. pylori gastritis and those with gastric
atrophy were 22 and 34 percent higher, respectively, than in the
reference group.
The 11 patients who had H. pylori infection had a higher
serum TSH concentration (1.35 mU/L) at the time of diagnosis of
the infection, as compared with 0.11 and 0.12 mU/L before and after
successful antibiotic and omeprazole therapy, while taking the same
dose of T4.
The 10 patients who had gastroesophageal reflux had a serum TSH
concentration of 0.10 mU/L, which increased to 1.70 mU/L during
treatment with omeprazole.
The conclusions of the study. Patients treated
with T4 need higher doses if they have H. pylori gastritis
or gastric atrophy or are treated with omeprazole, indicating that
gastric secretion of acid facilitates T4 absorption.
The original article. Centanni M, Gargano L, Canettieri
G, Viceconti N, Franchi A, Delle Fave G, Annibale B. Thyroxine in
goiter, Helicobacter pylori infection, and chronic gastritis.
N Engl J Med 2006;354:1787-95.
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