Subclinical hypothyroidism in grown-up congenital heart disease patients

Abstract

Subclinical hypothyroidism usually is asymptomatic, but it can be associated with various adverse cardiologic outcomes. With the objective of gaining insight into the role of thyroid-stimulating hormone (TSH) in congenital heart abnormalities, this study measured serum TSH concentrations in different subtypes of grown-up congenital heart disease (GUCHD) patients. Serum TSH (reference range, 0.34-5.6 mIU/L), creatinine, cholesterol, C-reactive protein (CRP), N-terminal proB-type natriuretic peptide (NT-pro-BNP), and 24-h proteinuria were measured in 249 GUCHD patients. Of 24 GUCHD patients (9.6 %) with a TSH level higher than 5.6 mUI/L, nine were cyanotic (37.5 %) and seven (29.1 %) had Down syndrome. The GUCHD patients with serum TSH exceeding 5.6 mIU/L had a significantly higher level of serum NT-pro-BNP (195.1 [0.28; 5,280.3] vs 57.6 [0.00; 929.8]; p = 0.001) and CRP (0.30 [0.06; 1.87] vs 0.16 [0.00; 1.40]; p = 0.011] than those with a TSH level of 5.6 mIU/L or lower. No significant differences were found in serum creatinine, lipids, or 24-h proteinuria between the two groups. The T4 concentrations in the GUCHD patients with TSH exceeding 5.6 mIU/L were within the normal range (0.89 ± 0.23 ng/dL). In the multivariate analysis, cyanosis (odds ratio [OR], 6,399; 95 % confidence interval [CI] 2,296-17,830; p < 0.001), Down syndrome (OR, 6,208; 95 % CI, 1,963-19,636; p = 0.002), and NT-pro-BNP concentrations (OR, 1,001; 95 % CI, 1,000-1,002; p < 0.026) proved to be risk factors for TSH levels higher than 5.6 mIU/L. Because subclinical hypothyroidism entails a cardiovascular risk, the authors postulate that TSH screening should be included in the routine follow-up evaluation of GUCHD patients with cyanosis or Down syndrome.