Aim: Endocrine Society (2016) published guidelines for hormonal replacement in hypopituitarism. Central hypothyroidism (CH) is defined as fT4 below reference range and mild CH is defined as fT4 in the low-normal range with suggestive symptoms in the context of pituitary disease. In patients with panhypopituitarism levothyroxine in doses sufficient to achieve fT4 levels in the upper half of the reference range is recommended. In our centre fT4 normal range is 1025 pmol/L. We audited our current clinical practice regarding levothyroxine replacement in patients post trans-sphenoidal surgery (TSS).
Method: Retrospective study of patients who underwent TSS from Jan13 Feb17 at a teaching hospital. Data were collected from electronic records.
Results: Sixty patients were included (31 male). Mean age 59±15.6 years. Forty-two patients underwent TSS for non-functioning adenomas (NFA), 8 for Acromegaly, 6 for Cushings disease and the rest due to other reasons. Pre-operatively 9 (15%) patients were on levothyroxine replacement, 7 of whom had secondary hypothyroidism. At the time of audit (April 2017), 36 (60%) patients were on levothyroxine, 26 of these were on additional hormonal replacement. One patient was on GH replacement alone with low-normal fT4 levels. Following the guidelines, 11/18 patients on levothyroxine had mild CH symptoms and as fT4 was in the lower half of normal range their dose was increased. 6/22 patients not on thyroid replacement had symptoms of mild CH with fT4 in lower half of normal range and were commenced on levothyroxine. Twelve patients on levothyroxine had fT4 in the top half of normal range.
Conclusions: The new guidelines have made us more vigilant with regards to levothyroxine replacement in patients with mild CH following TSS. Levothyroxine treatment in those patients with possible CH is clinician dependant. GH should not be started prior to correcting other hormone deficiencies including mild CH considering relative cost of therapies.