Thyroid function tests, serum lipids and gender interrelations in a middle-aged population

OBJECTIVE: To study the value of screening for thyroid function in a screening program for hyperlipidaemia. DESIGN: A screening study in primary health care. SETTING: All individuals in a defined rural area, Söderåkra, Sweden, aged 40-59 years were invited to a screening programme at the local primary health care centre. PARTICIPANTS: 782 individuals were invited for screening. Blood samples were obtained from 88% of the invited males and from 92% of the females. MAIN OUTCOME MEASURES: Thyroid function tests (thyroid stimulating hormone (TSH) and free T4), serum lipids (total-cholesterol, HDL-cholesterol, LDL-cholesterol and s-triglycerides), b-glucose and body anthropometry (body mass index and waist to hip circumference) were measured. RESULTS: 0.57% of males and 1.13% of females showed evidence of hypothyroidism as defined by a TSH value greater than 3.75 mU/l of those with s-cholesterol concentration above 7 mmol/l. In addition, higher TSH values in females were associated with higher s-cholesterol, s-LDL-cholesterol and s-triglycerides. CONCLUSION: It seems appropriate to screen for hypothyroidism in females with s-cholesterol above 7.0 mmol/l.