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K. L. L. MOVIG, R. BAUMGARTEN, H. G. M. LEUFKENS, J. H. M. VAN LAARHOVEN, and A. C. G. EGBERTS
Risk factors for the development of lithium-induced polyuria
The British Journal of Psychiatry 2003; 182: 319-323 [Abstract] [Full text] [PDF]
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[Read eLetter] Serotonergic drugs associated with polyuria- how strong is the association?
Sudhir Kumar   (19 May 2003)

Serotonergic drugs associated with polyuria- how strong is the association? 19 May 2003
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Sudhir Kumar,
Consultant Neurologist, Department of Neurological Sciences
Christian Medical College Hospital, Vellore, Tamilnadu, India-632004

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Re: Serotonergic drugs associated with polyuria- how strong is the association?

drsudhirkumar{at}yahoo.com Sudhir Kumar

To the editor,

I read with interest the recent article by Movig KLL et al (April, 2003). Association of serotonin reuptake inhibitors with polyuria is an interesting one.

However, I would like to make some observations. They note that the patients taking serotonergic antidepressants are four times more likely to develop polyuria as compared to non-users. Looking at Table 1 carefully, we find that out of 25 patients taking serotonergic drugs, 14 (56%) had polyuria and 11 (44%) did not have polyuria. Now, this difference is definitely not a strong one. If the sample size was large enough, strength of association could have easily been the other way.

Another point to note in Table 2 is that the fluid intake was significantly higher in the group of patients with polyuria; a mean intake of 4094 ml was noted in the polyuria group as compared to 2362 ml in the group without polyuria. Fluid intake is directly proportional to urine output and therefore high fluid intake could be factor responsible for the observed polyuria. Polydipsia is commonly seen in chronic psychiatric patients. A prevalence of 20.2% was seen in an earlier study (Ahmed AG et al, 2001). It is possible that the higher fluid intake in the polyuria group was due to the underlying psychiatric disease and not the drugs used.

If the authors were convinced that the polyuria was due to the serotonergic drugs, their finding could have been ascertained if they had substituted the serotonergic antidepressants with another antidepressants and rechecked the urine volumes. A fall in urine volume is expected if the proposed hypothesis is correct.

In conclusion, based on the data presented, it is uncertain that serotonergic antidepressants could lead to polyuria.

References

1.AG Ahmed, Liana M Heigh, KV Ramachandran. Polydipsia, psychosis and familial psychopathology. Can J of Psychiatry 2001; 46: 522-527. 2.K. L. L. Movig, R. Baumgarten, H. G. M. Leufkens, J. H. M. Van Laarhoven, and A. C. G. Egberts. Risk factors for the lithium-induced polyuria. Br J Psychiatry 2003; 182: 319-323.