Pattern of lithium exposure predicts poisoning severity: evaluation of referrals to a regional poisons unit.
BACKGROUND
Lithium toxicity may result in severe clinical features. There is on-going uncertainty about the significance of serum lithium concentrations in patients with lithium toxicity.


OBJECTIVE
To examine potential relationships between stated quantity of lithium ingested, serum lithium concentrations, and poisoning severity among patients referred to a regional poisons centre.


METHODS
Prospective evaluation of enquiries to the Scottish Poisons Information Bureau about lithium toxicity between 2000-2005 inclusive.


RESULTS
There were 172 enquiries, relating to acute ingestion (n = 101), acute-on-therapeutic ingestion (n = 38), or chronic poisoning (n = 33). Poisoning severity was moderate or severe in 9.9%, 26.3% (p < 0.05 vs. acute) and 54.5% (p < 0.005 vs. acute) of each group, respectively. Median (IQR) serum lithium concentrations in each group were: 2.4 (1.7-3.3) mmol/l, 2.1 (1.4-3.8) mmol/l, and 2.3 (1.9-3.3) mmol/l, respectively. The median stated quantities ingested in acute and acute-on-therapeutic lithium exposure were 5000 mg (2000-11 050 mg) and 4000 mg (2400-8820 mg), respectively.


CONCLUSIONS
Patients with acute-on-therapeutic and chronic poisoning are at greatest risk of severe toxicity. These differences cannot be explained by either the quantity of lithium ingested or serum lithium concentration alone.
Waring
W S
WS
Scottish Poisons Information Bureau, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, UK. s.waring@ed.ac.uk
Laing
W J
WJ
Good
A M
AM
Bateman
D N
DN
D000208:Acute Disease; D000328:Adult; D000368:Aged; D018692:Antimanic Agents / Q000506:poisoning*; D001714:Bipolar Disorder / Q000188:drug therapy*; D002908:Chronic Disease; D005260:Female; D006801:Humans; D018020:Lithium Compounds / Q000506:poisoning*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012017:Referral and Consultation / Q000592:standards*; D012606:Scotland
D018692:Antimanic Agents; D018020:Lithium Compounds