Data from a 20-year retrospective observational study conducted by researchers in Denmark suggest a need for improved thyroid status awareness in patients who also have hypopituitarism to reduce cardiovascular risk factors.
Researchers included patients with growth hormone deficiency who were started on replacement therapy between 1993 and 2009 (n=208). Based on baseline free thyroxine levels and treatment with or without levothyroxine, patients were categorized asthyroid-stimulating hormone sufficient (free T4 >12 pmol/L and not treated with levothyroxine) or TSH deficient (free T4 ≤12 pmol/L and treated with levothyroxine). Those who were TSH deficient were further divided into tertiles based on baseline free T4 levels: <13.1 pmol/L (first tertile; lowest); 13.1 pmol/L to 16.7 pmol/L (second tertile; intermediary); ≥16.8 pmol/L (third tertile; highest).
At baseline, serum free T4 was negatively associated to BMI and waist circumference. However, free T4 was positively associated with HDL, independent of age, sex and insulin-like growth factor I standard deviation score, researchers wrote.
Patients categorized in the first tertile of TSH deficiency displayed greater BMI (P=.02), total fat (P=.03), total cholesterol (P=.05), triglycerides (P<0.01), waist circumference (P=.01) and lower HDL (P=.03) compared with patients labeled as TSH sufficient.
After 4.1 years of follow-up, IGF-I, lean body mass and plasma glucose increased in all subgroups (P<.01), according to data. Changes to follow-up baseline free T4 were negatively correlated to changes in BMI, lean body mass, total cholesterol and LDL (all P<.05, adjusted for changes in IGF-I and GH and hydrocortisone dose), the researchers added. Patients in the first tertile of TSH deficiency were the only group to demonstrate a continued negative correlation to changes in total cholesterol and LDL.
“In this retrospective study of thyroid status and cardiovascular risk factors in GH-deficient patients, free T4 was negatively associated to BMI, waist and hip circumference, apparently explained by a worse profile in TSH-deficient patients with the lowest free T4, and as the patients came closer to euthyroid status, so did some cardiovascular risk factors get closer to normality,” researchers wrote.
Source: Endocrine Today