Bradycardia due to hypothyroidism

A middle-aged person who has no known significant medical history came in due to syncope (?)/fall. A few days prior,  patient noted headache, weakness, nausea and dizziness when getting up and changing position.  + decrease vision on R eye. No palpitations, chest pain, dyspnea, seizure,tingling, focal weakness. Noted weight gain of about 6 lbs for the past month. 

VS 120/70 36.3 HR 40's RR 25. Not in distress, awake and orriented x3, no jaundice, no hyperpigmentation, normocephalic and atraumatic, wet oral mucosa, no goiter or nodules, CBS, RR and no murmur, flat abdomen and no mass or tenderness, no LE edema.

CBC in reference range, trop neg x 3, glucose 100, Na 110's, K 3.3, Cl 80, bicarb 21, BUN 6, crea 0.7, Ca 8.3, PT/PTT - N, CXR normal. ECG was captured.CT head is pending.

What is the ecg saying about the who clinical scenario? —

Image 1 - 12 Lead

The ECG showed marked sinus bradycardia. 

So, we have here someone who presented with syncope with profound hyponatremia, headache, weight gain, decrease eye vision and profound bradycardia.

Patient was placed on hypertonic saline but serum sodium remained low. CT scan and MRI revealed a large pituitary mass with suprasellar extension (impingement on the optic chiasm). So in view of these, the thought is that the patient has central adrenal insufficiency and central hypothyroidism (low TSH and free T4). Patient underwent transnasal resection and multiple subspecialties were on-board for the case and discharged a few days after.

Image 2 - CT ST/MRI head / Pituitary Hormones

"The spectrum of clinical features of pituitary insufficiency depends on several factors. In acquired pituitary insufficiency, the clinical spectrum depends on the degree of hormone deficiency, the number of hormones impaired, and the rapidity of onset"

"The order of diminished trophic hormone reserve function related to pituitary compression usually is as follows: GH > FSH > LH > TSH > ACTH. The corticotrophic cell appears to be particularly resistant to hypothalamic or pituitary destruction, and it is usually the last cell to lose function. "

So, this is case is profound bradycardia due to hyopthyroiduism.

Reference:

Melmed S, et al. 2011. Williams Textbook of Endocrinology 12ed. PA Elsevier

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