Purpura associated with lithium intoxication.

Abstract

To the Editor: Lithium is now the drug of choice of treating bipolar affective disorders. The optimal steady-state concentration of lithium for maintenance treatment of bipolar disorders in generally considered to be 0.6–1.2 mmol/L, with slightly elevated steady state concentrations (0.8–1.4 mmol/L) indicated for the acute management of manic episodes. Because toxicity can occur at levels >1.4 mmol/L, lithium must be carefully monitored and lithium dosage adjusted as necessary. A 51-year-old male of Han ethnicity was admitted to our hospital, specialized psychiatric hospital, in January 2014 with a history of manic symptoms. His physical examination was normal; he was fully conscious, oriented and able to communicate. However, he talked excessively, had an elevated mood with inflated self-esteem, was irritable, acted bizarrely and had limited insight. Electroencephalogram and blood lipid were normal. Brain CT scans measurements of cortical and subcortical atrophy. He was treated with lithium carbonate. At that time his manic symptoms were under control. Soon after, there were red or purple discolorations on the skin that do not blanch on applying pressure [Figure ​[Figure1a1a and ​andb].b]. But his family members did not initially consider this an important enough problem to merit re-evaluation. However, his condition deteriorated rapidly so he was brought to give a clinical consultation, including clinical pharmacists. His white blood cell concentration was 10.49 × 109/L, the percentage of neutrophils was 82.4%, blood lithium was 1.01 mmol/L. Blood tests of liver and renal function were normal. It is worth noting that purpura covering much of the patient's lower extremities, scattered ecchymotic patches are found throughout his exam. His extremities are cold in temperature. Given the fact that common causes of purpura often can be identified during physical examination. When this condition occurs in a patient who has not had a known precipitating event, or when the cause is unclear from the history and physical examination, diagnosis may be based on findings of the laboratory investigations. However, he had the normal platelet count range 209 × 109/L. In light of the above findings, we believed that drugs may represent the cause of platelet dysfunction in case report.[1] Meanwhile, previous studies showed that skin reactions to lithium are common but can usually be managed. Lithium may worsen folliculitis (inflammation of hair follicle), psoriasis, and acne. Swollen feet are an uncommon side effect that responds to dose reduction.[2] In one word, these descriptions provide support for purpura related to lithium intoxication. Possible mechanism in this case may be immune complex mediated. Lithium is a hapten, and obtains immunity by binding the body protein. When the patients take lithium carbonate (the same antigen) after several days, the body will produce a series of antigen-antibody reaction. Purpura may be caused by auto-antibodies acting against certain platelet antigens.[3] As discussed above, it is equally likely that lithium is responsible for purpura. Thus, his lithium carbonate was stopped and he was administered an intravenous infusion of 250 ml mannitol. After 24 hours, his lithium concentration was 0.59 mmol/L. One week later, there was little purpura left on his skin. Figure 1 (a and b) Skin reactions to lithium. There were purple-colored spots (measure 1–3 cm) and patches on the skin. In this case lithium intoxication occurred at a lower blood concentration, at the middle of the therapeutic range. This highlights the need for clinicians to closely monitor the clinical status of patients for early symptoms of intoxication, even when lithium levels are in the normal therapeutic range.