Mohan T Shenoy and Dr Sanjay Kalra,
Around 5% of adults with new-onset hypercholesterolemia may have hypothyroidism, according to a prospective study published in the Endocrine Journal, a journal of the Japan Endocrine Society.1
Tetsuya Tagami from the Division of Endocrinology and Metabolism, National Hospital Organization Kyoto Medical Center, Kyoto in Japan and colleagues conducted a multicenter survey to evaluate thyroid function in 725 Japanese adults with either untreated or treated hypercholesterolemia from 2006 to 2008. Of these, 300 were males and 425 were females. Treated participants were on antihyperlipidemic agents, while the untreated subjects had total cholesterol (TC) levels above 220 mg/dL and/or LDL “bad” cholesterol (LDL-C) levels above 140 mg/dL. In the treated group, TC was 204.5 mg/dL and LDL-C was 119.6 mg/dL. Triglyceride levels were 144.4 mg/dL, HDL-cholesterol (HDL-C) 60.7 mg/dL and the LDL-C/HDL-C ratio (L/H) was 2.25.
More than half (51%) of those surveyed were hypertensive, while nearly half (49%) had diabetes; 17% had fatty liver. Around 15% were smokers and 10% engaged in habitual drinking.
The overall prevalence of hypothyroidism in patients with hypercholesterolemia was found to be 4.3%. Out of the 725 cases of hypercholesterolemia, 27 cases (3.7%) were diagnosed with primary hypothyroidism, with 11 cases in males and 16 cases in females. Additionally, 17 cases (2.4%) had subclinical hypothyroidism, and 10 cases (1.4%) had overt hypothyroidism. Central hypothyroidism was seen in 4 patients (0.6%). The BMI of patients with subclinical and overt hypothyroidism did not differ much, though patients with subclinical hypothyroidism had higher BMI. Female patients with subclinical hypothyroidism had higher BMI (29.0 kg/m2) than their male counterparts (24.1 kg/m2).
Hypercholesterolemia is an established risk factor for atherosclerotic cardiovascular disease (ASCVD), including stroke. These patients are routinely prescribed antihyperlipidemic drugs such as statins to lower their risk of heart disease. Considering the rising number of patients with dyslipidemia, it is important to mitigate the associated adverse effects. This study shows that patients who have been newly detected with high cholesterol levels should also be evaluated for thyroid function. Treating hypothyroidism may improve cholesterol levels.
Reference
- Tagami T, et al; PHPH study group. Multi-center study on the prevalence of hypothyroidism in patients with hypercholesterolemia. Endocr J. 2011;58(6):449-57. doi: 10.1507/endocrj.k11e-012.
Mohan T Shenoy is Consultant Endocrinologist, SGMCRF, Venjaramoodu, Trivandrum; and Dr Sanjay Kalra, DM (AIIMS); Imm. Past President, SAFES, Bharti Hospital, Karnal, India