Lithium-associated kidney microcysts

Long-term lithium treatment in bipolar disorder: effects on glomerular filtration rate and other metabolic parameters

Background

Concerns about potential adverse effects of long-term exposure to lithium as a mood-stabilizing treatment notably include altered renal function. However, the incidence of severe renal dysfunction; rate of decline over time; effects of lithium dose, serum concentration, and duration of treatment; relative effects of lithium exposure vs. aging; and contributions of sex and other factors all remain unclear.

Methods

Accordingly, we acquired data from 12 collaborating international sites and 312 bipolar disorder patients (6142 person-years, 2669 assays) treated with lithium carbonate for 8–48 (mean 18) years and aged 20–89 (mean 56) years. We evaluated changes of estimated glomerular filtration rate (eGFR) as well as serum creatinine, urea–nitrogen, and glucose concentrations, white blood cell count, and body-mass index, and tested associations of eGFR with selected factors, using standard bivariate contrasts and regression modeling.

Results

Overall, 29.5% of subjects experienced at least one low value of eGFR (<60 mL/min/1.73 m²), most after ≥15 years of treatment and age > 55; risk of ≥2 low values was 18.1%; none experienced end-stage renal failure. eGFR declined by 0.71%/year of age and 0.92%/year of treatment, both by 19% more among women than men. Mean serum creatinine increased from 0.87 to 1.17 mg/dL, BUN from 23.7 to 33.1 mg/dL, glucose from 88 to 122 mg/dL, and BMI from 25.9 to 26.6 kg/m². By multivariate regression, risk factors for declining eGFR ranked: longer lithium treatment, lower lithium dose, higher serum lithium concentration, older age, and medical comorbidity. Later low eGFR was also predicted by lower initial eGFR, and starting lithium at age ≥ 40 years.

Limitations

Control data for age-matched subjects not exposed to lithium were lacking.

Conclusions

Long-term lithium treatment was associated with gradual decline of renal functioning (eGFR) by about 30% more than that was associated with aging alone. Risk of subnormal eGFR was from 18.1% (≥2 low values) to 29.5% (≥1 low value), requiring about 30 years of exposure. Additional risk factors for low eGFR were higher serum lithium level, longer lithium treatment, lower initial eGFR, and medical comorbidity, as well as older age.

Renal sonography in bipolar patients on long-term lithium treatment

PURPOSE

The aim of the study was to analyze sonographic (US) renal findings in lithium-treated bipolar patients and to correlate them with renal function.

METHODS

Renal US and renal function tests were performed on 120 patients with bipolar disorder. Ninety patients (30 males, 60 females), aged 36-82 years, had received lithium therapy for an average of 16 years, whereas 30 patients (10 males, 20 females), aged 35-85 years, who had never been exposed to lithium, served as controls.

RESULTS

In the lithium-treated group, patients with macrocysts (22%) had poorer renal function with higher creatinine serum concentrations, lower estimated glomerular filtration rates, and lower urine specific gravity, compared with the patients without macrocysts. The US changes characteristic for lithium nephropathy (punctate hyperechoic foci, microcysts < 2 mm, and increased echogenicity) were seen in three patients. These patients had been treated with lithium for more than 20 years and had impaired renal function. Sixteen percent of patients in the control group had macrocysts; however, no correlation between their presence and impaired renal function was found.

CONCLUSIONS

The presence of macrocysts in the kidneys of lithium-treated bipolar patients is associated with impaired renal function. The US changes characteristic for lithium nephropathy are rare, and in our study, were only found in patients treated with lithium for 20 years or more. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:354-359, 2016.

Renal microcysts and lithium

OBJECTIVE

To review the relationship between lithium-related renal dysfunction and microcysts.

METHOD

Electronic databases (PubMed and Google Scholar) were queried.

RESULTS

From a total of 12,425 publications, 76 were reviewed.

DISCUSSION

Glomerular renal dysfunction occurs after an average of 20 years of continuous lithium treatment, and the severity is related to the total lithium load as measured by dose and duration. Recently, several reports have highlighted the relationship between renal microcyst formation and significant reductions in glomerular filtration rate. Radiologically visible lithium-related microcysts are usually 1-2 mm and occasionally 3 mm. Smaller cysts, which are impossible to resolve, are probably more common than the visible cysts, based on observations of renal needle biopsies. Increases in the number of microcysts and the space they occupy within kidney volume appear to be related to both the duration of lithium treatment and the reduction in kidney function. The proposed mechanism of microcyst formation is related to the antiapoptotic effect of lithium. Specifically, by preventing renal tubular epithelial cells from undergoing apoptosis as part of the process of normal renal maintenance, lithium may be allowing the inappropriate growth of the surface area of tubules to form invaginations and ultimately cysts. It is proposed that the physical space occupied by these cysts in the limited volume within the renal capsule compromises the function of otherwise healthy renal tissue. Monitoring of kidneys utilizing radiographic imaging may be more sensitive than monitoring laboratory values. Additional research is required to optimize this new monitoring tool.

Lithium nephropathy: a case report

Although widely used in the management of bipolar disorder, lithium may cause adverse kidney effects. The importance of the present study is to report the case of a 59-year-old woman who was under regular treatment with lithium for bipolar disorder and whose imaging studies demonstrated the presence of multiple renal microcysts, suggesting lithium nephropathy as main diagnostic hypothesis.

Lithium nephropathy: unique sonographic findings

This case series describes a unique sonographic appearance consisting of numerous microcysts and punctate echogenic foci seen on renal sonograms of 10 adult patients receiving chronic lithium therapy. Clinically, chronic renal insufficiency was present in 6 and nephrogenic diabetes insipidus in 2. Sonography showed numerous microcysts and punctate echogenic foci. Computed tomography in 5 patients confirmed microcysts and microcalcifications, which were fewer in number than on sonography. Magnetic resonance imaging in 2 patients confirmed microcysts in each case. Renal biopsy in 1 patient showed chronic interstitial nephritis, microcysts, and tubular dilatation. The diagnosis of lithium nephropathy should be considered when sonography shows these findings.