Hypothyroidism as a protective factor in acute stroke patients

It has been reported that hypothyroidism is associated with better survival in elderly persons. We investigated possible associations of thyroid status with clinical outcome in patients with acute stroke.

Retrospective analysis.

Consecutive patients (median age 70 years) admitted for acute stroke.

Total T3, T4 and TSH levels. Stroke severity evaluation using the Scandinavian Stroke Scale (SSS) and the Glasgow Coma Score (GCS). Handicap and survival assessment over 12 months.

Of 744 patients where thyroid function tests were available within the first 24 h of stroke, 13 had elevated TSH (>or= 10 microU/ml; range 10-42 microU/ml) (hypo-group), 51 had mildly elevated TSH (3.3-9.9 microU/ml) and 680 had nonelevated TSH < 3.3 microU/ml. In the hypo-group transient ischaemic attacks (TIA's) were more prevalent (46.2%) compared to the groups of mildly elevated TSH (11.8%) and nonelevated TSH (12.4%, P < 0.002). Hypo-group had more frequently an adequate level of consciousness (GCS 14-15 = fully alert): 92.3%vs 74.5% and 63.7% (P = 0.033), a milder neurological deficit (SSS score 45-58) 76.9%vs 39.2% and 38.7% (P = 0.02) compared to the other two groups, respectively, and a tendency for lower glucose levels on admission. One year outcome tended to be better with respect to survival and handicap.

Acute stroke patients with laboratory findings compatible with pre-existing hypothyroidism on admission, appear to have better clinical presentation and outcome; we speculate that a reduced response to stress and previous TIA's, possibly related to endogenous 'preconditioning', may contribute to this phenomenon.