Lithium toxicity: a double-edged sword.

CASE PRESENTATION A 62-year-old white male, with a bipolar disorder treated with lithium, a history of type II diabetes mellitus, and hypertension, was referred to the renal clinic for evaluation of nephrotic syndrome and stage IV chronic kidney disease (CKD) (Modification of Diet in Renal Disease glomerular filtration rate 26 cc/min/1.73 m). The patient had a history of bipolar disorder treated for over 10 years with lithium until 2 years ago when a diagnosis of nephrogenic diabetes insipidus and mild CKD was made and lithium discontinued. At that time, he had a urine osmolality of 272 mOsm/kg and a serum creatinine of 1.5 mg/dl. His medications included lisinopril, atenolol, gemfibrozil, haloperidol, quetiapine, metformin, and bupropion SR. There was no history of polyuria or polydipsia. Review of systems revealed no other significant symptoms. On examination, blood pressure was 133/64 mm Hg, heart rate 70 beats per minute, regular rhythm. Lung and cardiovascular examination were unremarkable. Abdomen was soft, nontender with no organomegaly. Extremities revealed trace edema. Urine examination revealed a specific gravity of 1.012, pH 5.5, 3þ protein, negative blood and no casts. His urine albumin creatinine ratio 3 months before was 3.9 g protein per gram creatinine. His laboratory investigations revealed BUN 40 mg/dl (reference range 9–25 mg/dl), creatinine 3.0 mg/dl (0.7–1.3 mg/dl), potassium 5.6 mEq/l (3.5–5.0 mmol/l), glucose 72 mg/dl (5–118 mg/dl), HbA1C 4.8 (4.2–5.8%), serum total proteins 6.2 g/dl (6–8 g/dl), albumin 3.5 g/dl (3.7–5.4 g/dl), cholesterol 208 mg/dl (140–199 mg/dl), triglycerides 626 mg/dl (35–150 mg/dl), low-density lipoprotein 78 mg/dl (50–129 mg/dl), hemoglobin 13.2 g/dl (11.5–16.4 g/dl), and hematocrit of 37.7% (36–48%). Complements and other serologic tests were negative. Renal ultrasound revealed bilateral nephromegaly (right kidney 12.6 cm and left kidney 12.9 cm) with a diffuse increase in echogenicity and innumerable tiny cysts throughout the kidney (cortex and medulla) (Figure 1). There was no evidence of hydronephrosis. A clinical diagnosis of nephrotic syndrome was made and it was decided to proceed to a kidney biopsy.