Lithium-associated clinical hypothyroidism. Prevalence and risk factors.
BACKGROUND
Rates of, and risk factors for, lithium-associated clinical hypothyroidism are uncertain.


OBJECTIVE
To determine prevalence of and risk factors for clinical hypothyroidism in patients treated with lithium carbonate.


METHODS
Retrospective case-note review of 718 patients who had undergone serum lithium estimation during a 15-month period. Patients on thyroxine had a more detailed review.


RESULTS
The prevalence of clinical hypothyroidism during lithium treatment was 10.4%. The main risk factor was female gender (women 14% v. men 4.5%). Women were at highest risk during the first two years of lithium treatment, and women starting lithium aged 40-59 years had the greatest prevalence (> 20%). No equivalent risk factors emerged in men, although, like women, their prevalence of hypothyroidism was substantially higher than community rates.


CONCLUSIONS
The high rates of clinical hypothyroidism identified may call for a review of the drug information given to women, particularly to those starting lithium in middle age. Consideration should be given to screening for thyroid antibodies before treatment in high-risk cases. Monitoring of thyroid function should take into account gender, age and stage of lithium treatment.
Johnston
A M
AM
Psychiatric Unit, Hairmyres Hospital, East Kilbride, Lanarkshire.
Eagles
J M
JM
D000328:Adult; D017677:Age Distribution; D000368:Aged; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000139:chemically induced* / Q000175:diagnosis; D016651:Lithium Carbonate / Q000009:adverse effects* / Q000097:blood; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D016019:Survival Analysis
D016651:Lithium Carbonate