[How we treat subclinical hypothyroidism in our daily clinical practice]

To study the therapeutic approach to subclinical hypothyroidism (HTS), the frequency of introducing replacement therapy, reasons for starting, doses, and duration, in the population over 14 years-old in a Primary Care Centre.

Longitudinal, retrospective observational study of 1156 patients with a hypothyroidism/myxedema episode (T86 in the International Classification of Primary Care (ICPC)) entered in the OMI program were studied. Excluded: 10 duplicates, 180 no inclusion criteria or inability to collect data, 25 diagnosed in another laboratory, 359 with clinical hypothyroidism (HTC).

Sex, age, TSH value to diagnosis and initiate treatment, or latest TSH recorded in the clinical history (HC) if not treated, TSH diagnostic confirmation, antiTPO antibodies (ATAs), presence of fatigue, goitre, neuropsychiatric symptoms, raised cholesterol, if HTS secondary, progression to HTC, diagnostic-start treatment interval, initial and final dose, duration, reasons for discontinuation.

582 patients: 508 women. Mean age: 43.03 (sd 15.97). HTS treated: 330 (56.7%); TSH at diagnosis < 10: 81.6%; Mean TSH treated: 11.22 (sd 10.49); Made ATAs performed: 315 (54%),+166 (52.7%); Fatigue not recorded in HC: 64%; Goitre: 65%. 67% untreated: returned to normal spontaneously. Starting dose: 86% ≤ 50μg. Final ≤ 50: 43%. Treatment duration: 1-5 years 41%; > 5 years 40%. Immediate treatment after diagnosis 38%. Remain treated 93%. Variables that increase the likelihood of onset of treatment (Logistic Regression): TSH value (OR 32.5, CI 12.8- 82.6), ATAs+(OR 4.7, CI 2.8-7.7); Fatigue (OR 2.5, CI 1.5-4), Goitre (OR 3, CI 1.3-6.6).

The decision to treat is generally adequate, but often becomes a chronic analytical disorder, because of unduly prolonged treatment without attempts to withdraw it. Clinical history and physical examination tend to be ignored.