Efficacy and Safety of Once-Weekly Thyroxine for Thyroxine-Resistant Hypothyroidism

Intramuscular and subcutaneous levothyroxine: success in treating refractory hypothyroidism

Introduction

Refractory hypothyroidism often poses a clinical problem, as treatment regimens are difficult to individualise to the patient and the feasibility of its delivery is difficult to organise within a healthcare system. We present a patient who became intolerant of intramuscular (IM) levothyroxine (LT4) after 18 years of treatment; thus, subcutaneous (SC) LT4 was initiated.

Case presentation

A 13-year-old female with newly diagnosed hypothyroidism remained hypothyroid despite escalating doses of oral LT4 and LT3. Thyroxine malabsorption was further suggested by nasogastric administration of LT4, whereby high-dose thyroxine administration resulted in only a 2.8 pmol/L increase in free T4 level (normal >5.14 pmol/L). She eventually achieved long-term euthyroid status at the age of 18 with fortnightly IM LT4 alongside oral LT4 and LT3. This was maintained for 18 years. Unfortunately, scar tissue developed around injection sites, resulting in increased pain and difficulty in administration. SC LT4 was trialled with success, and she has remained euthyroid for the last 6 years with self-administration and minimal side effects.

Conclusion

Refractory hypothyroidism often presents a challenge for clinicians, both for diagnosis and management. We discuss a patient with the longest follow-up to date within the published literature for both IM and SC LT4 for patient-administered treatment of refractory hypothyroidism and review the literature on alternative formulations available.

Twice or thrice weekly levothyroxine provides similar rates of adherence and post-Ramadan euthyroidism compared to daily levothyroxine during Ramadan fasting

BACKGROUND

Having to take levothyroxine (L-T4) on a daily basis, on an empty stomach is burdensome and may impair adherence, especially during Ramadan fasting. A long half-life and autoregulation of thyroid hormone levels allows for twice or thrice weekly administration of L-T4. This study aims to establish twice or thrice weekly L-T4 dosing as a convenient and effective practice during Ramadan fasting.

METHODS

The study included 2 groups; twice or thrice weekly (TTW) group included patients assigned to take L-T4 twice or thrice a week, and standard daily dosing (SDT) group included patients assigned to take L-T4 daily. Patients freely chose between three L-T4 regimens: before Iftar, before Suhor, or before the next fast. Thyroid status was assessed before and within 6 weeks after Ramadan. Only euthyroid patients were included.

RESULTS

TTW group included 57 patients, while SDT group included 91 patients. Pre-Ramadan TSH in TTW group (1.80 ± 0.88 µIU/L) was higher compared to SDT group (1.39 ± 0.72 µIU/L) [P = 0.003]. Similar adherence rates were observed in both groups, 96.5% in TTW group versus 89% in SDT group, [P = 0.13]. similar rates of post-Ramadan euthyroidism were also found in both groups, 91.2% in TTW group versus 94.5% in SDT group, [P = 0.509]. TTW group preferred regimen 1 (64.9%) significantly more than SDT group (35.2%) [P = 0.001].

CONCLUSION

Twice or thrice weekly levothyroxine results in similarly high rates of adherence (96.5%) and post-Ramadan euthyroidism (91.2%) compared to daily levothyroxine during Ramadan fasting.

SEVERE REFRACTORY HYPOTHYROIDISM IN A 48-YEAR-OLD FEMALE: ROLE OF LOW-DOSE THYROXINE ABSORPTION TEST IN ESTABLISHING DIAGNOSIS OF NONCOMPLIANCE

A 48-year-old female presented with severe chronic hypothyroidism despite progressively increasing doses of levothyroxine. Poor adherence was suspected based on previous laboratory investigations. A low dose thyroxine absorption test using 400 µg of levothyroxine taken orally was performed. FT4 increased by 4.7 pmol/L at 3 hours and 6.6 pmol/L at 5 hours, following ingestion, effectively ruling out malabsorption. Her cardiac hemodynamic profile, measured noninvasively, also improved following levothyroxine intake, further supporting our diagnosis. Poor adherence was successfully managed by implementing twice weekly visits by a registered nurse and an improvement in both thyroid function tests and cardiac parameters was seen at the one-month follow-up visit. We suggest using a lower dose thyroxine absorption test, owing to its efficacy in establishing diagnosis and a safer alternative compared to higher doses in particular in high-risk cardiac patients.

Twice or Thrice Weekly versus Daily Thyroxine in Hypothyroid Fasting Ramadan: A Pilot Study

CONTEXT

Hypothyroid patients require to take levothyroxine (L-T4) on an empty stomach, 60 min before next meal which is difficult to achieve while fasting Ramadan, on a daily basis. This pilot study aimed to assess the effect of twice or thrice weekly versus standard daily L-T4 dosing during Ramadan on adherence, post-Ramadan TSH, and thyroid status.

METHODS AND MATERIALS

The study included 2 groups; group 1 included 11 patients assigned to take L-T4 twice or thrice a week, and group 2 included 113 patients assigned to take L-T4 daily. Patients chose between three L-T4 regimens: regimen 1 - 60 min before Iftar; regimen 2 - 60 min before Suhor, on empty stomach for 3-4 h; regimen 3 - before the next fast, on empty stomach for 3-4 h. Thyroid status was assessed before and within 6 weeks after Ramadan. Only euthyroid patients were included.

RESULTS

No significant differences between the two groups regarding adherence, post-Ramadan TSH, or post-Ramadan thyroid status. 90.9% in group 1 and 88.5% in group 2 were adherent [p = 1.000]. Post-Ramadan TSH in group 1 was 1.9 ± 1.5 mIU/L, in group 2 was 2 ± 1.6 mIU/L [p = 0.809]. 81.8% in group 1 and 82.3% in group 2 were euthyroid post-Ramadan [p = 0.209].

CONCLUSIONS

In this pilot study, taking L-T4 twice or thrice weekly during Ramadan achieved similar adherence and metabolic control to standard daily L-T4, making it an easier option for hypothyroid patients wishing to fast Ramadan.

Weekly Versus Daily Levothyroxine Tablet Replacement in Adults with Hypothyroidism: A Meta-Analysis

Objectives

Daily levothyroxine is the treatment of choice and standard of care in hypothyroidism, sufficient to restore thyroid stimulating hormone (TSH) to normal range. For many patients, daily lifelong therapy is required, making adherence a major issue. In such cases, weekly replacement may be a suitable alternative to improve adherence. In this study, we aimed to determine the efficacy and safety of weekly levothyroxine replacement among adults with hypothyroidism.

Methodology

Electronic databases were searched. Two reviewers (HCC and RBL) independently screened the abstracts, reviewed full-text papers, critically appraised the quality of included studies using PRISMA guidelines. Meta-analysis was performed using the random-effects model. The primary outcome is the difference in serum TSH levels between weekly and daily administration, while secondary outcomes included adverse events and symptoms of hypothyroidism.

Results

The primary outcome is the difference in serum TSH levels between weekly and daily administration. Secondary outcomes included adverse events and clinical symptoms. The study included two randomized trials (n=109) in the primary analysis. The difference in TSH levels was 1.78 mIU/mL higher [(95% confidence interval (CI): 1.28 to 2.28, p<0.00001] at 6 weeks and 1.22 mIU/mL higher (95% CI: 0.76 to 1.67, p<0.00001) at 12 weeks for the weekly regimen. There was no significant heterogeneity between the two groups. There was no significant difference in hypothyroid symptoms and adverse events before and after levothyroxine treatment within each group.

Conclusions

Weekly levothyroxine resulted in less suppression and higher mean serum TSH levels, while still remaining within the normal reference range. It may be a suitable alternative for non-adherent patients. However, larger randomized trials with longer duration of follow-up are needed to firmly establish its role.

Effect of once weekly oral levothyroxine therapy

SUMMARY

Primary hypothyroidism is one of the most common endocrine disorders with widely available treatment. A minority of patients remain with uncontrolled hypothyroidism despite therapy. The objective of this case series was to demonstrate that medication non-adherence, rather than malabsorption, should be sought as the most common cause of unsuppressed TSH levels in patients receiving treatment for this condition. Non-adherence is often considered as a diagnosis of exclusion. Nonetheless, a diagnosis of malabsorption requires a more extensive workup, including imaging and invasive procedures, which increase healthcare costs and burden to the patient. The findings of this study allow for a cost-effective approach to uncontrolled hypothyroidism.

LEARNING POINTS

Medication non-adherence is a common cause of insuppressible TSH levels. Once weekly levothyroxine is an alternative approach to non-compliant patients. Assessing compliance is more cost-effective and less burdensome than testing for malabsorption.

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.