Levothyroxine Therapy Precipitating Adrenal Crisis in a Patient with Central Adrenal Insufficiency

Presentation Number: SUN 371
Date of Presentation: April 2nd, 2017

Amrutha Mary George*1 and Jessica L Hwang2
1Rush University Medical Center, Chicago, IL, 2John H Stroger Hospital, Chicago, IL

Abstract

Background: Levothyroxine therapy precipitating Addisonian crisis (primary adrenal insufficiency) has been reported

multiple times in the past especially in the setting of polyglandular autoimmune syndrome. Levothyroxine therapy

unmasking well-compensated secondary adrenal insufficiency is much rarer and has not been reported before.

Case: A 61 year old female with a history of hypertension was evaluated by her primary care physician for mild fatigue.

Her vitals were normal. Basic labs demonstrated normal comprehensive metabolic panel, normal blood count and a TSH

of 9.67 uIU/ml (reference range 0.34-5.6). No T4 was checked at the time. She was prescribed levothyroxine 50 mcg

daily.

One week after initiation of levothyroxine, she presented with dizziness, nausea and vomiting. Vitals were significant for

tachycardia and mild hypotension. The rest of her physical exam was unremarkable. Her sodium level on admission was

121 meq/L (135-145) and decreased with 0.9% normal saline to 118 in the emergency department. Serum osmolality was

255 mosm/kg (270-300), urine osmolality 265 mosm/kg (50-600), urine sodium 100 meq/L. On admission, TSH was 1.59 uIU/ml(0.340-5.60)

and free T4 was 0.43 ng/dL (0.58-1.64). 8 AM cortisol was checked and was found to be extremely low at 1.14 ug/dl

(4.46-22.70), ACTH was inappropriately normal at 11 pg/ml (6-50). She was started on hydrocortisone 60 mg in the AM,

20 mg in the PM for 1 day with dramatic improvement of sodium to 127 and 131 after 48 hours- hydrocortisone was

weaned quickly to 10 mg twice daily. Subsequent ACTH stimulation test results were consistent with secondary adrenal

insufficiency. By this point her sodium completely normalized.

She denied any head trauma or history of glucocorticoid use in the past. Labs showed low FSH and LH confirming central

hypogonadism. MRI of the pituitary revealed an empty sella.

Discussion: Studies on the effects of hypothyroidism on the hypothalamic-pituitary- adrenal axis have concluded that

there is decreased metabolic clearance of cortisol and increased sensitivity of the pituitary to CRH. It is for these reasons

that on initial presentation to the clinic this patient appeared well-compensated.

There exists a common endocrine teaching pearl- in patients with simultaneous hypothyroidism and adrenal

insufficiency, start adrenal replacement before thyroid replacement to avoid precipitating an adrenal crisis. The

prevalence of adrenal insufficiency in hypothyroid patients is less than 1%, so it is not cost-effective to screen all patients with

hypothyroidism for adrenal insufficiency.

This case is unique in that starting levothyroxine unmasked secondary (not primary) adrenal insufficiency due to empty

sella syndrome.

 

Nothing to Disclose: AMG, JLH