Myxedema Coma
Definition:
➧ The end-stage of untreated or insufficiently treated hypothyroidism.
Pathogenesis of Myxedema: (Figure 1)
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| Figure 1: Pathogenesis of Myxedema Coma |
Precipitating factors:
➧ CVA
➧ Myocardial infarction
➧ Infection (UTI, Pneumonia)
➧ Gastrointestinal hemorrhage
➧ Acute trauma
➧ Administration of sedative, narcotic, or potent diuretics
Typical clinical picture:
➧ Elderly obese female
➧ Becoming increasingly withdrawn, lethargic, sleepy, and confused
➧ Slips into a coma
History:
➧ Previous thyroid surgery
➧ Radioiodine
➧ Default thyroid hormone therapy
Physical findings:
➧ Comatose or semi comatose
➧ Dry coarse skin
➧ Hoarse voice
➧ Thin dry hair
➧ Delayed reflex relaxation time
➧ Hypothermia
➧ Pericardial, pleural effusions, ascites
Laboratory tests:
➧ Free T4 low and TSH high
➧ If the T4 is low and TSH low normal consider pituitary hypothyroidism
➧ Blood gases
➧ Electrolytes and creatinine
➧ Distinguish from the euthyroid sick syndrome
➧ Low T3, Normal or low TSH, normal free T4
ECG in a patient with Myxedema Coma: (Figure 2)
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| Figure 2: ECG in Myxedema Coma |
Management of Myxedema:
➧ ICU admission: may be required for ventilatory support and IV medications.
➧ Parenteral thyroxine: Loading dose of 300-500 μg IV, then 50-100 μg/d. IV or 100-200 μg/d. oral
➧ Glucocorticoids: Hydrocortisone: 100 mg/8 h. for 1 week, then taper.
-Controversial but necessary in hypopituitarism or multiple endocrine failures.
➧ Electrolytes:
-Water restriction for hyponatremia
-Avoid fluid overload
➧ Avoid sedation
Prognosis:
➧ Mortality is 20% and is mostly due to underlying and precipitating diseases.
Read more ☛ Thyroid Storm
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