We don’t have a lack of information. We have a lack of accurate and valuable information. If you are interested in reading more about the actual published research, you can find the summary and the link to the research below.
Factors Affecting Gastrointestinal Absorption of Levothyroxine: A Review
A study of studies, where the authors reviewed all the relevant published research relating to the factors that affect the gastrointestinal absorption of levothyroxine (synthetic T4). They found several factors that significantly impact absorption: gastrointestinal disorders (such as celiac disease, lactose intolerance, and H. pylori infection), soybeans, coffee, medications (such as cholestyramine, colesevelam, lanthanum, calcium carbonate, calcium citrate, calcium acetate, iron sulfate, ciprofloxacin, aluminum hydroxide, sevelamer, or proton pump inhibitors).
Gastrointestinal Malabsorption of Thyroxine
The authors examined the pharmacologic features of T4 preparations and their linkage with the intestinal absorption of the hormone. They also reviewed the interfering role of nutrients, foods, and drugs on T4 absorption within the gastric and intestinal levels, as well as the impact of gastrointestinal disorders on T4 treatment efficacy. They also listed the binding ingredients (excipients) of each T4 preparation and mentioned that these binding ingredients can also impact absorption rates.
Thyroid Hormone Regulation of Metabolism
The authors looked at thyroid hormones and their impact on metabolism. Thyroid hormones regulate metabolic processes essential for normal growth and development as well as regulating metabolism in the adult. Hyperthyroidism, excess thyroid hormone, promotes a hypermetabolic state characterized by increased resting energy expenditure, weight loss, reduced cholesterol levels, increased lipolysis, and gluconeogenesis. Hypothyroidism, reduced thyroid hormone levels, is associated with hypometabolism characterized by reduced resting energy expenditure, weight gain, increased cholesterol levels, reduced lipolysis, and reduced gluconeogenesis.
Zinc Deficiency Associated with Hypothyroidism: An Overlooked Cause of Severe Alopecia
Hypothyroidism is a common and well-recognized cause of diffuse hair loss. Zinc and other trace elements such as copper and selenium are required for the synthesis of thyroid hormones, and deficiency of these can result in hypothyroidism. Conversely, thyroid hormones are essential for the absorption of zinc, and hence hypothyroidism can result in acquired zinc deficiency. The hair loss attributed to hypothyroidism may not improve with thyroxine unless zinc supplements are added, as demonstrated in our case.