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Systolic Time Interval (STI) in hypothyroid patients receiving high dose L-thyroxine

Zakaria, Nurul Aulia and Pasi, Hafizah and Shahar, Mohammad Arif (2019) Systolic Time Interval (STI) in hypothyroid patients receiving high dose L-thyroxine. In: 5th Medical Research Symposium 2019, 9th October 2019, IIUM Medical Centre, Kuantan, Pahang. (Unpublished)

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Abstract

INTRODUCTION: Systolic Time Interval (STI) is a simple,noninvasive and precise technique to assess left ventricular (LV) function. It measures aortic Pre-Ejection Period (PEP) over Left Ventricular Ejection Time (LVET) from echocardiogram. Thyrotoxicosis will enhance LV function and cause reduction of STI. OBJECTIVES : This study was perform to measure the changes of STI after administration of high dose L-thyroxine and to determine the correlation between high dose L-thyroxine administration and STI METHOD : A Total of 22 patients were screened. Those with cardiac diseases and high Framingham risk score were excluded. Nine patients were started on high dose L-thyroxine (7x their usual dose) once a week during the month of Ramadan. Thyroid hormones ( T3,T4,TSH) and STI (PEP/LVET) were measured at baseline and within 24 hrs after high dose of L-thyroxine ingestion. RESULTS : All patients have normal thyroid hormones level and normal cardiac function at baseline. The median dose (mcg) of L-thyroxine was 600 (437.5,700) while the median level of fT4 level was 17.43(12.38,20.8). Despite the significant increment of fT4 after L-Thyroxine ingestion [baseline 13.21(8.19,14.63) vs high dose 17.43(12.38,22.55) p= 0.011] there was no significant change in STI [baseline 0.3(0.2,0.4) vs high dose 0.28(0.26,0.45) p; 0.513]. There was no correlation found between the dose of L-thyroxine and STI (r=0.244 , p;0.526). CONCLUSION : Administration of high dose L-thyroxine did not significantly alter STI, unlike the naturally occurring thyrotoxicosis.Therefore ‘exogenous’ administration of high dose L-thyroxine is cardiac safe.

Item Type: Conference or Workshop Item (Poster)
Additional Information: 7231/81835
Uncontrolled Keywords: STI,L-thyroxine,high dose,safe
Subjects: R Medicine > RC Internal medicine > RC648 Specialties of Internal Medicine-Diseases of The Endocrine Glands. Clinical Endocrinology
R Medicine > RC Internal medicine > RC667 Specialties of Internal Medicine-Diseases of Circulatory (Cardiovascular) System
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button): Kulliyyah of Medicine > Department of Internal Medicine
Kulliyyah of Medicine
Depositing User: Dr Nurul Aulia Zakaria
Date Deposited: 03 Aug 2020 15:20
Last Modified: 03 Aug 2020 15:20
URI: http://irep.iium.edu.my/id/eprint/81835

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