Monitoring patients on lithium

Sir: I read the recent paper by Nicholson and Fitzmaurice (Psychiatric Bulletin, September 2002, 26, 348-351) with interest. Their literature review preceded the publication of our fairly recent study (Eagles et al, 2000) that investigated lithium monitoring before and after the distribution of clinical practice guidelines in the north-east of Scotland. From our findings, I would wish to extend, and to mildly contest, some of the points made by Nicholson and Fitzmaurice.

With regard to specific points within the Lothian Guidelines, there are two points. Thyroid dysfunction occurs, commonly, more in women than in men and especially during the first 2 years of lithium treatment (Johnston & Eagles, 1999). It is probably logical, therefore, certainly in the early years of lithium treatment, to monitor thyroid function at 6-monthly intervals. Second, I agree that there is no good evidence on which to base advised serum levels; Nicholson and Fitzmaurice selected 0.6-1.0 mmol/l, while we advise 0.5-1.0 mmol/l. It is important to note that, within this range, some patients may respond only at higher serum levels (Gelenberg et al, 1989).

As we did in north-east Scotland (Eagles et al, 2000), Nicholson and Fitzmaurice intend to audit the effect of circulating lithium monitoring guidelines in Lothian. We found that guidelines significantly improved the monitoring of renal and thyroid function. More importantly, however, standards of monitoring were poor before and after guideline distribution, and remained even poorer among patients who were no longer in contact with psychiatric services. We endorsed Cookson's (1997) conclusion that all patients on lithium should remain in contact with an experienced psychiatrist.