Clinical relevancy of the levothyroxine-continuous enteral nutrition interaction.
BACKGROUND
The objective of this study was to determine if patients requiring levothyroxine therapy develop hypothyroidism during concurrent continuous enteral nutrition (EN).


METHODS
Adult patients with a history of hypothyroidism, given levothyroxine via the feeding tube at the same dose given prior to hospital admission and who were referred to the nutrition support service for EN were evaluated. Thyroid function tests (TFTs) were performed prior to administration of levothyroxine-continuous EN, then approximately weekly thereafter. Patients who received less than 14 days of concurrent EN-levothyroxine therapy were excluded from the analysis.


RESULTS
Thirteen patients who received 20 ± 5 days of concurrent EN and levothyroxine were evaluated. Two patients developed subclinical hypothyroidism (thyrotropin [TSH] >6 and <10 mcIU/mL + normal fT(4)), and 6 developed overt hypothyroidism (TSH >10 mcIU/mL + low fT(4)) within 2 to 3 weeks of concurrent EN-levothyroxine therapy. Five patients remained euthyrotic. Differences between those who developed subclinical or overt hypothyroidism versus those who remained euthyrotic could not be explained by age, weight, levothyroxine dose, type of EN formula, or amount of EN received.


CONCLUSIONS
More than half of the patients receiving concurrent levothyroxine-continuous EN developed subclinical or overt hypothyroidism requiring therapeutic intervention. Routine weekly monitoring of TFTs for patients receiving concurrent levothyroxine-continuous EN is recommended.
University of Tennessee Health Science Center, Memphis, TN 38163, USA. rdickerson@uthsc.edu
Roland N
RN
Dickerson
George O
GO
Maish
Gayle
G
Minard
Rex O
RO
Brown
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004750:Enteral Nutrition / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D013960:Thyroid Function Tests; D013974:Thyroxine / Q000009:adverse effects*
D013974:Thyroxine