Myxedema coma of both primary and secondary origin, with non-classic presentation and extremely elevated creatine kinase

Myxedema Coma Associated with Macroprolactinoma: Case Report and Review of the Literature

Myxedema coma is a rare life-threatening presentation of severe hypothyroidism associated with a high mortality rate. Although most cases are due to primary thyroid failure, a minority have central hypothyroidism as the underlying cause. We report the case of a 69-year-old man who presented with obtundation, hypoglycemia, and hyponatremia. The patient's initial thyroid-stimulating hormone (TSH) was within normal limits. Subsequent evaluation revealed critical anterior pituitary insufficiency due to a macroprolactinoma and a diagnosis of myxedema coma after appropriate workup The finding of a normal serum TSH should not eliminate the possibility of myxedema coma.

The hypothalamus-pituitary-thyroid (HPT)-axis and its role in physiology and pathophysiology of other hypothalamus-pituitary functions

The hypothalamus-pituitary-thyroid axis is one of several hormone regulatory systems from the hypothalamus to the pituitary and ultimately to the peripheral target organs. The hypothalamus and the pituitary gland are in close anatomical proximity at the base of the brain and extended through the pituitary stalk to the sella turcica. The pituitary stalk allows passage of stimulatory and inhibitory hormones and other signal molecules. The target organs are placed in the periphery and function through stimulation/inhibition by the circulating pituitary hormones. The several hypothalamus-pituitary-target organ axis systems interact in very sophisticated and complicated ways and for many of them the interactive and integrated mechanisms are still not quite clear. The diagnosis of central hypothyroidism is complicated by itself but challenged further by concomitant affection of other hypothalamus-pituitary-hormone axes, the dysfunction of which influences the diagnosis of central hypothyroidism. Treatment of both the central hypothyroidism and the other hypothalamus-pituitary axes also influence the function of the others by complex mechanisms involving both central and peripheral mechanisms. Clinicians managing patients with neuroendocrine disorders should become aware of the strong integrative influence from each hypothalamus-pituitary-hormone axis on the physiology and pathophysiology of central hypothyroidism. As an aid in this direction the present review summarizes and highlights the importance of the hypothalamus-pituitary-thyroid axis, pitfalls in diagnosing central hypothyroidism, diagnosing/testing central hypothyroidism in relation to panhypopituitarism, pointing at interactions of the thyroid function with other pituitary hormones, as well as local hypothalamic neurotransmitters and gut-brain hormones. Furthermore, the treatment effect of each axis on the regulation of the others is described. Finally, these complicating aspects require stringent diagnostic testing, particularly in clinical settings with lower or at least altered à priori likelihood of hypopituitarism than in former obvious clinical patient presentations.

Sudden Cardiac Arrest in a Patient With Myxedema Coma and COVID-19

SARS-CoV-2 infection is associated with significant lung and cardiac morbidity but there is a limited understanding of the endocrine manifestations of coronavirus disease 2019 (COVID-19). Although thyrotoxicosis due to subacute thyroiditis has been reported in COVID-19, it is unknown whether SARS-CoV-2 infection can also lead to decompensated hypothyroidism. We present the first case of myxedema coma (MC) in COVID-19 and we discuss how SARS-CoV-2 may have precipitated multiorgan damage and sudden cardiac arrest in our patient. A 69-year-old woman with a history of small cell lung cancer presented with hypothermia, hypotension, decreased respiratory rate, and a Glasgow Coma Scale score of 5. The patient was intubated and administered vasopressors. Laboratory investigation showed elevated thyrotropin, very low free thyroxine, elevated thyroid peroxidase antibody, and markedly elevated inflammatory markers. SARS-CoV-2 test was positive. Computed tomography showed pulmonary embolism and peripheral ground-glass opacities in the lungs. The patient was diagnosed with myxedema coma with concomitant COVID-19. While treatment with intravenous hydrocortisone and levothyroxine were begun the patient developed a junctional escape rhythm. Eight minutes later, the patient became pulseless and was eventually resuscitated. Echocardiogram following the arrest showed evidence of right heart dysfunction. She died 2 days later of multiorgan failure. This is the first report of SARS-CoV-2 infection with MC. Sudden cardiac arrest likely resulted from the presence of viral pneumonia, cardiac arrhythmia, pulmonary emboli, and MC-all of which were associated with the patient's SARS-CoV-2 infection.

Interactions between hypothalamic pituitary thyroid axis and other pituitary dysfunctions

Central hypothyroidism is defined as low circulating free thyroxine (free T4) with inappropriately low circulating thyrotropin (TSH), in context of a hypothalamic pituitary pathology. Rare cases of idiopathic central hypothyroidism caused by a functional defect may occur, and the condition is often overlooked due to difficulty in achieving the correct diagnosis, sparse symptomatology of the condition and a high risk of misinterpretion of the biochemical changes in central hypothyroidism. Central hypothyroidism is mainly seen in patients with hypothalamic-pituitary pathology due to one of many possible aetiologies, where other hormone deficiencies often co-exist, and both the presence of other deficiencies and their replacement have a strong influence on the measurement of the thyroid-related hormones and thereby interpretation of the thyroid function variables in relation to the clinical impact of thyroid hormone substitution therapy. Conversely, lack of thyroid hormone has a similar strong influence on the interpretation of other pituitary hormone axes, as well as their replacement. Undertreating patients with central hypothyroidism may have serious metabolic consequences with a potentially increased risk of cardiovascular morbidity. The present review thus aims at describing central hypothyroidism, by an overview of interactions of hypothyroidism with other pituitary hormones, diagnosing/testing for central hypothyroidism, and focusing on consequences of undertreatment. Finally, it is mentioned how to deal with new diagnostic settings with lower a priori likelihood of hypopituitarism, particularly in view of the importance of stringent diagnostic testing in order to avoid overdiagnosing central hypothyroidism.

A case of myxedema coma caused by isolated thyrotropin stimulating hormone deficiency and Hashimoto's thyroiditis

Myxedema coma (MC) is a rare, but often fatal endocrine emergency. The majority of cases that occur in elderly women with long-standing primary hypothyroidism are caused by particular triggers. Conversely, MC of central origin is extremely rare. Here, we report a case of MC with both central and primary origins. A 56-year-old woman was transferred to our hospital due to loss of consciousness; a chest x-ray demonstrated severe cardiomegaly. Low body temperature, bradycardia, and pericardial effusion suggested the presence of hypothyroidism. Endocrinological examination revealed undetectable levels of serum free thyroxine (T(4)) and free triiodothyronine (T(3)), whereas serum thyroid-stimulating hormone (TSH) levels were not elevated. The woman's serum anti-thyroid peroxidase antibody and anti-thyroglobulin antibody tests were positive, indicating that she had Hashimoto's thyroiditis. Provocative tests to the anterior pituitary revealed that she had TSH and growth hormone (GH) deficiency; however, GH levels were restored after supplementation with levothyroxine for 5 months. This was not only a rare case of MC with TSH deficiency and Hashimoto's thyroiditis; the patient also developed severe osteoporosis and possessed transient elevated levels of serum carcinoembryonic antigen (CEA). This atypical case may suggest the role of anterior pituitary hormone deficiencies, as well as hypothyroidism, in the regulation of bone metabolism.

Predictors of outcome in myxoedema coma

Myxoedema coma is a rare and life-threatening illness the outcome of which has not been robustly studied in large numbers, partly due to its low incidence. Dutta and colleagues have explored outcome predictors in a developing country where access to thyroid function tests is more limited than in the Western world. Cardiovascular instability, reduced consciousness, persistent hypothermia, and sepsis all contributed to a poorer outcome, as has been demonstrated before, but a generic outcome predictor model was shown to be useful in this group of patients. Unfortunately, this observational study was unable to show differences in outcome based on replacement treatment methods and the mortality remains at 40%.