IGF1 and hypothyroidism: Last, it was shown that serum levels of IGF-I and IGFBP3 were significantly low in patients with hypothyroidism,34 a risk factors for heart failure.35 We did not add hypothyroidism in the multivariable-adjusted model because none of the cases or the controls in our study had reported having a history of hypothyroidism through the self-administered questionnaire.