■ Coma Mixedematoso I (Myxedema Coma I)
– Myxedema coma is a rare condition with high morbidity.
– This disease may be easily misdiagnosed even in patients presenting with cardinal sings such as hypothermia.
– The determination of thyroxine levels should be performed immediately in all patients presenting with bradycardia, bradypnea, elevated CPK, hypoxemia, and ileus.
– Hyponatremia, hypercholesterolemia, liver or cardiac enzyme elevations, and respiratory insufficiency are frequently present.
– In the setting of suspected myxedema coma with increased CPK levels, free thyroxine must be assessed immediately.
– Some patients taking amiodarone may develop thyroid dysfunction in the form of amiodarone-induced thyrotoxicosis (AIT) or amiodarone-induced hypothyroidism (AIH) The incidence of AIH ranges from 6% in countries with low iodine intake to 13% in countries with a high dietary iodine intake.
– Females with positive thyroglobulin or anti-thyroid peroxidase antibodies have a 13-fold higher incidence of AIH when compared to males without thyroid antibodies.
– Measurement of T3 hormone may be helpful in cases with thyroxine hormone replacement in the setting of myxedema coma arising during treatment with amiodarone due to its extrathyroidal T3 inhibitory effect. This could explain the lack of response in our patient presenting in myxedema coma during amiodarone treatment.
– The diagnosis of this condition is more difficult in the elderly when the T4 value is over 1 mcg/dl as seen in the euthyroid sick syndrome.
– Treatment of myxedema coma should be immediately initiated once the diagnosis is suspected, even without laboratory confirmation. Management consists of supportive therapy, hormone replacement, and treatment of precipitating factors.
– Intravenous thyroid hormone therapy replacement is the cornerstone in the treatment of patients.
– Myxedema coma as the initial manifestation of hypothyroidism is rarely described in the literature, given the gradual appearance of clinical symptoms suggesting the presence of a thyroid disease.
■ Myxedema coma: four patients diagnosed at the Internal Medicine Department of the Dr Negrin University Hospital in Spain
N L Villalba, A Zulfigar, V Saint-Mezard et al
PAMJ 2019, vol 34 (7)
https://www.panafrican-med-journal.com/content/article/34/7/full/
■ Amiodarone-associated myxedema coma
E Zagorski, S Jayatilaka, F Hirani, A Donato
Am J Case Rep 2020, vol 21: e926757-e926757-3
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7556348/
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■ Mixedema & Macroprolactinoma (Myxedema & Macroprolactinoma)
– Myxedema coma is an endocrine emergency that requires a high index of suspicion given its high mortality rate. Unusual underlying causes, such as tumoral hypopituitarism, can impede diagnosis due to the lack of elevated TSH levels.
– Severe hypothyroidism meeting the definition of myxedema coma is associated with a significant mortality rate (30–50%), even with standard therapy
– There are many potential underlying causes of MC. Two of the most common are autoimmune thyroid failure (e.g., Hashimoto thyroiditis) and post-thyroidectomy hypothyroidism.
– Given that the vast majority (>95%) of myxedema coma cases are due to primary hypothyroidism
– Myxedema coma has also been reported rarely in patients with central hypothyroidism due to hypothalamic or pituitary diseases.
– The most common precipitating factors in myxedema cases are hypothermia, cessation of thyroid supplements, severe infections, anesthetics, tranquilizers, respiratory failure, and stroke
– In patients with myxedema coma due to central hypothyroidism, the TSH is typically low or normal, and these patients often have other features of hypopituitarism
– Patients with macroprolactinomas have various patterns of hypopituitarism
– Mental status can gradually deteriorate; however, if precipitated by a severe infection, trauma, central nervous system depressants, or a sudden cardiovascular event, rapid onset of stupor or obtundation may ensue, termed myxedema coma.
– Regardless of the etiology of the myxedema coma, management with high-dose intravenous levothyroxine as a loading dose, followed by a weight-based daily dose, remains the gold standard for therapy to help reverse the severe hypometabolic state in MC patients. Intravenous hydrocortisone should also be administered initially or concurrently, as patients with MC often have relative adrenocortical deficiency, which can worsen as the replacement thyroid hormone increases the metabolic rate
■ Myxedema coma associated with macroprolactinoma: case report and review of the literature
E J Omoniyi, R J Robbins
Case Rep Endocrinol 2022; 2022: 1591616
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9072034/
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■ Coma Mixematoso II (Myxoedema Coma II)
– Myxoedema coma is an endocrine emergency which presents when a patient with longstanding untreated hypothyroidism is no longer able to maintain physiological adaptations to profound hypothyroidism due to an acute precipitant.
– Myxoedema coma occurs more commonly in females (80%), almost exclusively in the over 60s, and 90% of cases occur in winter. This is because common causes of decompensation are hypothermia and infection. Other precipitants are medications, surgery, GI haemorrhage and myocardial infarction
– The three main presenting features are altered mental state, hypothermia and the presence of a precipitating event
■ Myxoedema coma masquering as acute stroke
C Butter, N Rashid, R Banatwalla, T FitzGerald
Eur J Case Rep Intern 2020, vol 7 (7): 001563
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7350959/
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■ Coma Mixedematoso: Casos Clínicos (Myxedema Coma: Case Reports)
Arquivo Blog Internet Médica – março 2021
https://internetmedica.com.br/coma-mixedematoso-casos-clinicos-myxedema-coma-case-reports/
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Maio 2022