Chronic Lithium Use Need Not Always Be "Chronic"

Introduction: Lithium induced nephropathy is typically considered to be a slowly progressive kidney disease with a reported latency period of 20 years from initiation of lithium to ESKD. Here, we present a case of progressive CKD within 2 years of initiation of lithium for bipolar disorder. Case Description: 22-year-old female with bipolar disorder and ADHD was referred to renal clinic for progressive decline in renal function in a span of 1.5 years. Her serum creatinine (S. Cr) was 0.86 mg/dl in January of 2023 and 1.7 mg/dl in July 2024 and later with no interim labs to compare. Lithium initiation for severe suicidal ideation was the only change in the interim with levels being closely monitored by her psychiatrist and reported to be in therapeutic range. She was also taking low dose Adderall for ADHD. She reported no polyuria or polydipsia. Further work up revealed bland urine with normal sized kidneys on renal ultrasound with no significant structural abnormalities reported. A kidney biopsy done revealed multiple small tubular cysts with chronic interstitial changes (Image 1) pointing towards Lithium induced nephrotoxicity. Lithium was promptly discontinued after discussion with her psychiatrist and her S. Cr improved from 1.9 mg /dl to 1.3 mg/dl within 4 months. Discussion: The incidence of lithium induced nephrotoxicity leading to ESKD is reported to be very low, 0.2 to 0.7%, still a staggering 8-fold increase when compared to general population. The rate of decline in eGFR is reported to be around 0.92 ml/min/1.73m2 per year of lithium treatment. While rapid decline in renal function with lithium levels being maintained in therapeutic range is rare, our case signifies the importance of maintaining high clinical suspicion and early diagnosis to prevent further decline in renal function.