Cardiac Troponin Is Elevated in Patients with Thyrotoxicosis and Decreases as Thyroid Function Improves and Brain Natriuretic Peptide Levels Decrease. | Read by QxMD (original) (raw)

Natsuko Watanabe, Jaeduk Yoshimura Noh, Naomi Hattori, Kenji Iwaku, Nami Suzuki, Ai Yoshihara, Hidemi Ohye, Miho Suzuki, Masako Matsumoto, Kei Endo, Yo Kunii, Gen Takagi, Kiminori Sugino, Koichi Ito

INTRODUCTION: High-sensitive cardiac troponin reflects micro-myocardial injury in the absence of overt myocardial infarction.

OBJECTIVE: This study aimed to clarify how thyrotoxicosis affects cardiac troponin.

METHODS: This was a prospective observational study in Japan. Untreated patients with thyrotoxicosis who visited Ito Hospital were enrolled, and medical treatment was initiated for hyperthyroidism. Thyroid function, high-sensitive troponin I (hsTnI), and brain natriuretic peptide (BNP) were measured at baseline and then every 3 months for 1 year.

RESULTS: Data from a total of 143 patients (median age, 42 years; 32 men and 111 women) were investigated. At baseline, median hsTnI was 1.9 pg/mL and ranged from 0 to 69.6 pg/mL. Five patients (3.5%) had a high hsTnI value that exceeded 26.2 pg/mL, which is used as the cutoff for diagnosis of myocardial infarction, and 22 patients (15.4%) had an intermediate value between 5.0 and 26.2 pg/mL. Multivariable regression analysis showed that significant predictors of the hsTnI value were age (β = 0.20, p = 0.01) and BNP (β = 0.43, p < 0.0001) ( R 2 = 0.27, F = 26.0, p < 0.0001), and significant predictors of the BNP value were age (β = 0.23, p = 0.001), hemoglobin (β = -0.43, p < 0.0001), free T4 (FT4 ) (β = 0.23, p = 0.001), and hsTnI (β = 0.27, p < 0.0001) ( R 2 = 0.49, F = 33.8, p < 0.0001). Correlations were found between a decrease in hsTnI and BNP in the first 3 months (ρ = 0.49, p < 0.0001). A decrease in FT4 in the first 3 months was weakly correlated with decreases in hsTnI (ρ = 0.32, p = 0.0004) and BNP (ρ = 0.32; p = 0.0003). Of the 27 patients with elevated hsTnI (≥5.0 pg/mL), the hsTnI level was normalized in 20 patients within a year.

CONCLUSIONS: In thyrotoxicosis, the myocardial biomarker hsTnI is elevated in about 20% of patients; hsTnI levels decrease as thyroid function improves and BNP decreases.