LITHIUM

Etiology

1. Acute toxicity occurs when 40mg/kg are ingested at once.
    
2. Chronic toxicity occurs when pt drinks few fluids, dehydration (summer time), hyponatremic state. This occurs because at the level of  kidneys Li is reabsorbed  instead of Na+.
   
   Note: side effects may be confused with  toxicity and Li level is needed to properly differentiate between the two.

S & S:

Acute:

1. CNS = ataxia, confusion, lethargy, tremor, dizziness, tinnitus, psychosis.
    
2. GI = N/V/D,
    
3. CV= bradycardia, ST changes, conduction defects, > QT,  TW
    
4. CBC = neutrophilia
    
5. RENAL = DI (Polydipsia, Polyuria)

Chronic:

1. DI, myocarditis, skin ulcers, CNS (as above),  WBC, hypoTSH. CNS manifestations are the most noticeable.

DX:

    1.  Serum level of Li >4.0mEq/L in acute case and > 1.5mEq/L in case of chronic toxicity.
         Therapeutic level is 0.6 – 1.2 mEq/L.

Treatment:

1. GI lavage even several hrs. after ingestion. AC is not effective.
    
2. IVF with NS is a must since kidneys need Na+ supply otherwise Li will be reabsorbed.
    
3. Hemodialysis indicated when: ¯ UO or CRF, severe signs of toxicity, no improvement of symptoms with above treatment, and/or level above 4.0mEq/L. After the dialysis Li level rises and repeat serum levels must be obtained in 4-6hrs.     

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