Central hypothyroidism and its replacement have a significant influence on cardiovascular risk factors in adult hypopituitary patients

Abstract

Context: Thyroid dysfunction may have detrimental effects on patient outcomes. Few studies have assessed this issue in patients with secondary hypothyroidism. Objective: Our objective was to test the hypothesis that thyroid hormone status has an impact on cardiovascular risk factors in adult patients with hypopituitarism. Design and Setting: This was a retrospective observational study (1993-2012) at a tertiary referral university hospital. Patients: All GH-deficient patients starting GH replacement (1993-2009) with measured free T4 (fT4) (n 208). Baseline fT4 defined patients as TSH-sufficient and TSH-deficient (further divided into tertiles according to baseline fT4; first tertile had lowest fT4). Main Outcome Measures: Anthropometric (body mass index [BMI], waist circumference, total fat (fat mass) and lean body mass [LBM]) and biochemical (lipids and fasting plasma glucose) data were collected at baseline and a median 4.1 years after commencement of GH. Results: At baseline, fT4 was negatively associated with BMI and waist circumference, but positively with high-density lipoprotein, independent of age, gender, and IGF-I (SD score). Only first-Tertile TSHdeficient patients had higher BMI (P=.02), fat mass (P=.03), total cholesterol (P=.05), triglycerides (P = .01), and waist circumference (P = .01), and lower high-density lipoprotein cholesterol (P = .03) as compared with TSH-sufficient patients. At follow-up, IGF-I, LBM, and plasma glucose had increased in all subgroups (P=.01). The change in fT4 (=fT4) (follow-upbaseline) was negatively correlated to =BMI, =LBM, =total cholesterol, and =low-density lipoprotein cholesterol (all P < .05, adjusted for δIGF-I and δGH and hydrocortisone dose). The negative correlation to =total cholesterol and δlowdensity lipoprotein cholesterol persisted only in first-Tertile TSH-deficient patients. Conclusion: This single-center study over a 20-year period has strengthened the importance of improved awareness of thyroid status and optimal thyroid replacement of hypopituitary patients to reduce cardiovascular risks in hypopituitary patients. Copyright © 2013 by The Endocrine Society.