Qu'est ce qu'un taux de TSH élevé ?

Measurement of TSH is the most sensitive test of thyroid function. The diagnostic of mild forms of dysthyroidism depends of the definition of the normal limits of serum TSH. The upper limit of TSH remains controversial. The conventional cut off of 4 to 4,5 mU/l is now under debate. Recent laboratories guidelines indicate that more than 95% of normal individuals have TSH levels below 2,5 mU/l. However this statistical value is not clinically receivable when summarizing the data available in several populations. The application of such an upper value of TSH would dramatically increase the diagnosis of subclinical hypothyroidism and might increase the use of thyroxin therapy in patients for whom there is no demonstrated therapeutic benefit. In conclusion, the conventional reference range of TSH from 0,4 to 4 mU/l remains applicable in a care practice setting.