Répercussions biologiques de l'hypothyroïdie fruste

Subclinical hypothyroidism, defined by an isolated increased TSH level, is a frequently encountered condition the clinical outcomes of which are difficult to assess. It's therapeutic management is being discussed. It is essential that biological changes resulting from subclinical hypothyroidism should be known, because they contribute to the prognosis of this condition. Conversion to overt hypothyroidism is not systematic. It is however more likely to occur when the TSH concentration exceeds 10 mUI/l and in patients with thyroid autoimmunity. The impact of subclinical hypothyroidism, as a cardiovascular risk factor seems to be related to lipid abnormalities. An increase in total cholesterol and LDL-cholesterol, reversible with thyroxine treatment, is significant only when the TSH concentration exceeds 10 mUI/l. New biological risk factors - Lp(a), CRP, plasmatic homocysteine - are neither disturbed nor influenced by thyroxine treatment. Other biological abnormalities are less significant and do not contribute to the diagnosis or prognosis of subclinical hypothyroidism.