Rectal Levothyroxine for the Treatment of Hypothyroidism: A Case Study

Thyroid dysfunction in infants with severe intestinal insufficiency: a case series

OBJECTIVE

The aim of this study was to describe the status of thyroid function in infants with severe intestinal dysfunction.

CASE DESCRIPTION

A retrospective study was conducted in a tertiary neonatal intensive care center, including newborns and infants with severe intestinal dysfunction, hospitalized between 2015 and 2020. From the medical records, the following data were collected: gestational age, birth weight, underlying pathology that led to intestinal dysfunction, hospital stay, presence of thyroid dysfunction, age from the onset of thyroid dysfunction, initial and maximum dose of levothyroxine replacement, and levothyroxine administration route and outcome. Seven children (0.76% of 914 hospitalizations) developed severe intestinal insufficiency: vanishing gastroschisis (42.9%), Berdon syndrome (28.5%), apple peel (14.3%), and OIES syndrome (14.3%) - omphalocele, exstrophy of cloaca, imperforate anus, and spina bifida. The mean gestational age was 33.3±1.6 weeks, the mean birth weight was 2,113.9±370.9 g, the median hospitalization was 420 days, and mortality was 42.9%. Of these seven cases, four (57.1%) presented thyroid dysfunction, evaluated by blood hormone dosages and the dose of levothyroxine replacement ranged from 25 to 100 μg/day, administered by gastric or rectal route.

COMMENTS

This series of cases draws attention to thyroid dysfunction (hypothyroidism) in children with severe intestinal insufficiency receiving exclusive parenteral nutrition for a prolonged period, whose etiology is iodine deficiency, because, in Brazil, micronutrient solutions added to parenteral nutrition do not contain iodine.

Levothyroxine: Conventional and novel drug delivery formulations

Despite the fact that levothyroxine is one of the most prescribed medications in the world, its bioavailability has been reported to be impaired by many factors, including interfering drugs or foods and concomitant diseases, and persistent hypothyroidism with a high dose of levothyroxine is thus elicited. Persistent hypothyroidism can also be induced by noninterchangeability between formulations and poor compliance. To address these issues, some strategies have been developed. Novel formulations (liquid solutions and soft-gel capsules) have been designed to eliminate malabsorption. Some other delivery routes (injections, suppositories, sprays, and sublingual and transdermal administrations) are aimed at circumventing different difficulties in dosing, such as thyroid emergencies and dysphagia. Moreover, nanomaterials have been used to develop delivery systems for the sustained release of levothyroxine to improve patient compliance and reduce costs. Some delivery systems encapsulating nanoparticles show promising release profiles. In this review, we first summarize the medical conditions that interfere with the bioavailability of oral levothyroxine and discuss the underlying mechanisms and treatments. The efficacy of liquid solutions and soft-gel capsules are systematically evaluated. We further summarize the novel delivery routes for levothyroxine and their possible applications. Nanomaterials in the levothyroxine field are then discussed and compared based on their load and release profile. We hope the article provides novel insights into the drug delivery of levothyroxine.

Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology

Background: An ENDO-European Reference Network (ERN) initiative was launched that was endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology with 22 participants from the ENDO-ERN and the two societies. The aim was to update the practice guidelines for the diagnosis and management of congenital hypothyroidism (CH). A systematic literature search was conducted to identify key articles on neonatal screening, diagnosis, and management of primary and central CH. The evidence-based guidelines were graded with the Grading of Recommendations, Assessment, Development and Evaluation system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. Summary: The recommendations include the various neonatal screening approaches for CH as well as the etiology (also genetics), diagnostics, treatment, and prognosis of both primary and central CH. When CH is diagnosed, the expert panel recommends the immediate start of correctly dosed levothyroxine treatment and frequent follow-up including laboratory testing to keep thyroid hormone levels in their target ranges, timely assessment of the need to continue treatment, attention for neurodevelopment and neurosensory functions, and, if necessary, consulting other health professionals, and education of the child and family about CH. Harmonization of diagnostics, treatment, and follow-up will optimize patient outcomes. Lastly, all individuals with CH are entitled to a well-planned transition of care from pediatrics to adult medicine. Conclusions: This consensus guidelines update should be used to further optimize detection, diagnosis, treatment, and follow-up of children with all forms of CH in the light of the most recent evidence. It should be helpful in convincing health authorities of the benefits of neonatal screening for CH. Further epidemiological and experimental studies are needed to understand the increased incidence of this condition.

Alternative routes of levothyroxine administration for hypothyroidism

PURPOSE OF REVIEW

The aim of the article is to present the basics of oral levothyroxine (LT4) absorption, reasons why patients may have persistently elevated serum thyroid stimulation hormone (TSH) levels, and alternative strategies for LT4 dosing.

RECENT FINDINGS

Although oral LT4 tablets are most commonly used for thyroid hormone replacement in patients with hypothyroidism, case studies report that liquid oral LT4, intravenous, intramuscular, and rectal administration of LT4 can successfully treat refractory hypothyroidism.

SUMMARY

Hypothyroidism is one of the most common endocrine disorders encountered by primary care physicians and endocrinologists. LT4 is one of the most widely prescribed medications in the world and it is the standard of care treatment for hypothyroidism. Generally, hypothyroid patients will be treated with LT4 tablets to be taken orally, and monitoring will occur with routine serum thyroid tests, including TSH concentrations. However, many patients fail to maintain serum TSH levels in the target range while managed on oral LT4 tablets. A subset of these patients would be considered to have poorly controlled hypothyroidism, sometimes termed refractory hypothyroidism. For these patients, optimization of ingestion routines and alternative formulations and routes of administration of LT4 can be considered, including oral liquid, intravenous, intramuscular, and even rectal formulations.