C-reactive Protein Levels in Patients With Autoimmune Hypothyroidism Before and After Levothyroxine Treatment

Hypothyroidism is one of the most common endocrine disorders. Most patients with hypothyroidism have autoimmune thyroiditis (Hashimoto's), characterized by elevated concentrations of anti-thyroperoxidase (ATPO) antibodies. Both overt hypothyroidism (OH) and subclinical hypothyroidism (SH) have been associated with cardiovascular risk factors, including markers of inflammation. High-sensitivity C-reactive protein (hs-CRP) is a veridical marker of systemic inflammation. Even a minor increase in hs-CRP is considered a cardiovascular risk; therefore, evidence of a beneficial effect of levothyroxine treatment on hs-CRP could be an argument in favor of therapy for SH.

To assess hs-CRP levels in patients with hypothyroidism and evaluate levothyroxine treatment's effect on hs-CRP.

This is a cohort study in which patients with hypothyroidism were evaluated before and after treatment with levothyroxine.

37 patients (17 with OH and 20 with SH) and 38 healthy controls were included in the study. hs-CRP was measured at the baseline visit, then after 2 and 4 months of levothyroxine therapy at a dose necessary to achieve euthyroidism as evidenced by a normal level of thyroid-stimulating hormone (TSH).

hs-CRP was significantly increased in OH (p < 0.001) and SH (p = 0.001) at baseline as compared to controls. hs-CRP significantly decreased in SH (2.2±1.6 mg/L at baseline visit, 1.4±1.1 mg/L after 2 months of levothyroxine treatment, P = 0.017) and tended to decrease in OH (2.3±1.6 mg/L at baseline visit, 1.6±1.1 mg/L after 4 months of levothyroxine treatment, P = 0.067*).

Patients with hypothyroidism have increased hs-CRP levels compared to a healthy control group and, thereby, a moderately increased cardiovascular risk. Achievement of euthyroidism by levothyroxine treatment decreased the levels of hs-CRP in patients with hypothyroidism.