Increased lithium dose requirement in a hyperglycemic patient.
OBJECTIVE
To report a case of apparent increased lithium clearance in a patient with persistent hyperglycemia.


METHODS
Lithium doses, blood glucose concentrations, and lithium plasma concentrations were evaluated in a patient during a 53-day inpatient admission for exacerbation of bipolar disorder. The lithium dose required to increase the lithium plasma concentration by 0.1 mEq/L was computed from the lithium dose and corresponding lithium plasma concentration. This value was correlated with the blood glucose concentration.


RESULTS
A plot of the lithium dose required to increase the lithium plasma concentration by 0.1 mEq/L versus the blood glucose concentration exhibited a direct linear relationship (r2 = 0.62). This plot indicates that higher lithium doses are needed during hyperglycemic states compared with euglycemic states to achieve equivalent plasma concentrations.


CONCLUSIONS
Glycosuria associated with hyperglycemia induces an osmotic diuresis that increases the renal clearance of lithium, necessitating higher lithium doses to maintain therapeutic lithium plasma concentrations.
Cyr
Monica
M
Lakeland Regional Medical Center, FL, USA.
Guia
Melanie A C
MA
Laizure
S Casey
SC
D000328:Adult; D001714:Bipolar Disorder / Q000188:drug therapy; D001786:Blood Glucose; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism*; D008094:Lithium / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use; D008297:Male; D008657:Metabolic Clearance Rate
D001786:Blood Glucose; D008094:Lithium