Vol 63, No 4 (2012)
Review paper
Published online: 2012-08-30
The influence of lactose intolerance and other gastro-intestinal tract disorders on L-thyroxine absorption
Endokrynol Pol 2012;63(4):318-323.
Abstract
The preferred treatment for hypothyroidism is oral levothyroxine (LT4) ingestion, in doses that ensure a sustained state of hormonal balance.
Many different factors may significantly influence the absorption of LT4, including: interval between the ingestion of the drug and
the last meal, eating habits, and different functional and organic pathologies of the gastro-intestinal tract.
The main purpose of this paper is to review and systematise the available literature on the subject of the influence of different malabsorption
syndromes on the effectiveness of LT4 preparations.
The need to use high LT4 doses in the substitutional treatment of hypothyroidism is often the very first sign of one of the pathologies that
are connected with malabsorption syndrome, which might have been asymptomatic and undiagnosed previously. Patients who require
more than 2 μg/kg body weight of LT4 per day, with constantly increased thyrotropin level, should be diagnosed with the suspicion of
pseudomalabsorption or real absorption disorder. An LT4 absorption test, using high doses of LT4, may be useful in the diagnosis of pseudomalabsorption.
After excluding non-compliance, the differential diagnosis should include such disorders as lactose intolerance, coeliac
disease, atrophic gastritis, Helicobacter pylori infection, bowel resection, inflammatory bowel disease, and parasite infection.
Where there is a diagnosis of lactose intolerance, both a low lactose diet and a lactose-free LT4 preparation should be administered to restore
euthyroidism or make it possible to decrease the dose of the LT4 preparation. In coeliac disease, a gluten-free diet usually allows a normalisation
of the need for LT4, as do eradication of the H. pylori infection or parasite colonisation. In cases of atrophic gastritis or inflammatory bowel disease,
treating the underlying diseases and regaining the state of remission may improve the absorption of LT4. In patients after gastro-intestinal tract
surgery, a dose of LT4 higher than that typically used is needed to restore euthyroidism
Keywords: hypothyroidismL-thyroxinemalabsorptionlactose intolerancecoeliac disease
![](https://journals.viamedica.pl/plugins/generic/popups/images/icons/close.png)