Weak, unwell & puffy

Morning report today was about a young patient presenting with abdominal pain, but then was found to have a history of generally feeling unwell, reportedly becoming “puffier”, gaining weight, and simply not feeling well. Physical examination included normal vitals (not what we were expecting), but significant for delayed, or “hung” reflexes, nonpitting edema throughout, as well as generalized weakness.

Ultimately, investigations revealed a TSH of > 100

Hypothyroidism ranges from subclinical hypothyroidism, overt hypothyroidism, all the way to myxedema coma.

The pathogenesis all stems from the lack of intracellular T3 and lack of conversion from T4.  This leads to cardiac dysfunction including hypothermia, bradycardia, diastolic hypertension, and if severe enough hemodynamic compromise. It also results in fluid retention and vascular impermeability which leads to hyponatremia and edema respectively. In severe cases (myxedema), CNS disturbance occurs including coma.

Remember that in severe cases ie myxedema coma, always look for a precipitating factor, which is most commonly infection, but can include cardiac events, stroke, gi bleeds, and drugs/toxins (including the rare case of bok choy induced myxedema, which is due to the thyroid inhibiting effects of metabolites of uncooked bok choy).

Clues to diagnosis on labs may include an elevated CK (hypothyroid myopathy, seen in this case as well), increased cholesterol levels and elevated liver enzymes. Also keep in mind that adrenal insufficiency can often keep the company of hypothyroidism, as do other autoimmune conditions, remembering that autoimmune thyroid disease (ie Hashimoto’s) is the most common, and part of the diagnosis is looking for these antibodies.

Treatment should be aimed at treating any underyling precipitating cause, and thyroid replacement. Remember that T3 is the active form, and that in times of systemic illness there is decreased conversion from T4 (ie the sick euthyroid syndrome characterized by normal TSH, low T3, normal T4 and elevated reverse T3).

Also remember that thyroid hormone may increase cortisol excretion and can worsen underlying adrenal insufficiency, so remember to keep an eye for that as well.

See this review article on myxedma coma for more details (the above image is from this 2011 article by Vivek et. al in the Journal of Thyroid Research).