Today Eric presented an interesting case of a young Filipino man with no medical history, presenting with chronic intermittent proximal > distal muscle weakness affecting mainly his lower extremities, with associated tremors, weight loss, sweats. He was found to be profoundly hypokalemic on presentation.
What is it?
- Severe hypothyroidism leading to AMS and hypothermia
- Can have other symptoms related to the slowing down of organs
Who gets it?
- Usually older females with long standing hypothyroidism triggered by a precipitating event
How does it present?
- Change in mental status (rarely presents as true overt coma)
What labs should you check?
- TSH, FT4
- Cortisol (to rule out concurrent adrenal insufficiency)
What is the treatment?
- IV T3 and/or T4 – data is mixed
- Use IV because patient likely has gut edema so PO form may have decreased absorption
- T3 has better bioavailability and is the active form
- In acute illness, body’s normal conversion of T4 to T3 is impaired
- Monitor patients on telemetry because biggest concern is arrhythmias
- Use lower dosing in elderly patients or those with cardiac disease
- Recheck TSH in one week – goal is drop by > 50%
- Stress dose steroids (hydrocortisone 100 mg every 8 hours)
- Until you rule out concomitant adrenal insufficiency
- Supportive measures
- Avoid dilute fluids which can worsen hyponatremia
- Use passive rewarming
- Pressors if needed
Remember that prolactin is inhibited by dopamine!
In panhypopituitaryism, the anterior pituitary hormones are more commonly affected than the posterior pituitary hormones and there is a spectrum for how much of the HPA axis is still preserved depending on the etiology of the panhypopituitaryism.
The hormones that need replacement in adults are T4 and cortisol. Testosterone can be replaced if needed in men. Estrogen and progesterone can be replaced in pre-menopausal women who do not want fertility at that time or in post-menopausal women to relieve post-menopausal symptoms. If a woman desires fertility and has enough HPA axis preserved then patients can get pulsatile GnRH to stimulate FSH and LH production to induce ovulation.
To screen for adrenal insufficiency, check a morning cortisol at 8am.
- Cortisol < 3 = likelihood high – check ACTH to determine primary versus secondary adrenal insufficiency
- Cortisol 3-18 = indeterminate – do further stimulation testing
- Cortisol > 18 = likelihood low – pursue other diagnosis
- Cosyntropin test – give cosyntropin (synthetic ACTH) and then measure cortisol level 1 hour later – normal is cortisol level > 18; if less than that, then likely primary adrenal insufficiency
- Insulin induced hyperglycemia test – give 0.1U/kg of insulin and check glucose at 15, 30, 60, 90, 120 minutes. Once glucose reaches < 50 then cortisol should be > 18
- Metyrapone testing – blocks 11B hydroxylase which leads to a drop in cortisol and increase in ACTH and increase in 11-deoxycortisol
- Insufficient dosing of steroids
- Failure to increase dosage of steroids with acute illness
- Persistent vomiting or diarrhea causing malabsorption of steroids
- Can commonly see isolated ACTH presentation in panhypopituitaryism
- Dexamethasone if adrenal insufficiency not yet diagnosed because it does not interfere with cortisol testing
- Hydrocortisone if pre-existing diagnosis
Remember – if you suspect adrenal insufficiency, give stress dose steroids immediately without waiting for further testing!