Endocrine Abstracts

A lot of debate has been going on over when to treat subclinical hypothyroidism. Some studies plead to lower the consensus TSH cutoff value of 10 mUI/l in order to improve general well-being and cardiovascular risk factors with early LT4 treatment. Our study aim was to assess progression of subclinical to overt hypothyroidism and to identify factors that would benefit from early treatment. A cohort of 76 patients with subclinical hypothyroidism was studied retrospectively, over a period of 36 months. We assessed general well being, features of metabolic syndrome, thyroid function tests, ATPO, cardiac function before and after treatment with levothyroxine. Subclinical hypothyroidism was classified as grade I (TSH 4.5–9.9 mUI/l), grade II (TSH 10–14.9 mUI/l), grade III (TSH 15–20 mUI/l), and sub-subclinical hypothyroidism (TSH 2.5–4.4 mUI/l associated with an high titres of ATPO). Substitutive treatment was commenced at a value of TSH above 6 mUI/l. Results: Initial TSH value was a strong predictor for disease progression seen in 25% of patients with sub-subclinical hypothyroidism, 35% with grade I subclinical hypothyroidism, 43% with grade II and 69% with grade III. Patients with negative ATPO titres had a significant lower incidence of developing overt hypothyroidism than patients with positive titres. General well being improvement was reported in 52%, 16% felt worse and 32% reported no change in symptoms. There was no significant improvement in BMI and slight improvement in serum lipids (−3.8% for total cholesterol and −7.9% for LDL). The lipid lowering effect of LT4 was greater in the subset of patients with pre-treatment hypercholesterolemia. Myocardial contractility and diastolic function were subtly impaired in 15 patients with grade II and III subclinical hypothyroidism and improved with LT4 treatment.

Substitutive treatment in subclinical hypothyroidism grade II and III has benefits on symptoms, lipid profiles and cardiac function. No evidence was found that grade I and sub-subclinical hypothyroidism would benefit from early treatment.