Renal function in 153 manic-depressive patients treated with lithium for more than five years

Managing polyuria during lithium treatment: a preliminary prospective observational study

Objectives:

Lithium-treated patients with polyuria are at increased risk of lithium toxicity. We aimed to describe the clinical benefits and risks of different management strategies for polyuria in community lithium-treated patients.

Methods:

This is a naturalistic, observational, prospective 12-month cohort study of lithium-treated patients with polyuria attending a community mental health service in Dublin, Ireland. When polyuria was detected, management changed in one of four ways: (a) no pharmacological change; (b) lithium dose decrease; (c) lithium substitution; or (d) addition of amiloride.

Results:

Thirty-four participants were diagnosed with polyuria and completed prospective data over 12 months. Mean 24-hour urine volume decreased from 4852 to 4344 ml (p = 0.038). Mean early morning urine osmolality decreased from 343 to 338 mOsm/kg (p = 0.823). Mean 24-hour urine volume decreased with each type of intervention but did not attain statistical significance for any individual intervention group. Mean early morning urine osmolality decreased in participants with no pharmacological change and increased in participants who received a change in medication but these changes did not attain statistical significance. Only participants who discontinued lithium demonstrated potentially clinically significant changes in urine volume (mean decrease 747 ml in 24 hours) and early morning urine osmolality (mean increase 31 mOsm/kg) although this was not definitively proven, possibly owing to power issues.

Conclusions:

Managing polyuria by decreasing lithium dose does not appear to substantially improve objective measures of renal tubular dysfunction, whereas substituting lithium may do so. Studies with larger numbers and longer follow-up would clarify these relationships.

Diagnostic Accuracy of Tests for Polyuria in Lithium-Treated Patients

In lithium-treated patients, polyuria increases the risk of dehydration and lithium toxicity. If detected early, it is reversible. Despite its prevalence and associated morbidity in clinical practice, it remains underrecognized and therefore undertreated. The 24-hour urine collection is limited by its convenience and practicality. This study explores the diagnostic accuracy of alternative tests such as questionnaires on subjective polyuria, polydipsia, nocturia (dichotomous and ordinal responses), early morning urine sample osmolality (EMUO), and fluid intake record (FIR). This is a cross-sectional study of 179 lithium-treated patients attending a general adult and an old age psychiatry service. Participants completed the tests after completing an accurate 24-hour urine collection. The diagnostic accuracy of the individual tests was explored using the appropriate statistical techniques. Seventy-nine participants completed all of the tests. Polydipsia severity, EMUO, and FIR significantly differentiated the participants with polyuria (area under the receiver operating characteristic curve of 0.646, 0.760, and 0.846, respectively). Of the tests investigated, the FIR made the largest significant change in the probability that a patient experiences polyuria (<2000 mL/24 hours; interval likelihood ratio, 0.18 and >3500 mL/24 hours; interval likelihood ratio, 14). Symptomatic questioning, EMUO, and an FIR could be used in clinical practice to inform the prescriber of the probability that a lithium-treated patient is experiencing polyuria.

Risk factors for polyuria in a cross-section of community psychiatric lithium-treated patients

OBJECTIVES

Polyuria increases the risk of dehydration and lithium toxicity in lithium-treated patients. Risk factors have been inconsistently described and the variance of this adverse effect remains poorly understood. This study aimed to establish independent risk factors for polyuria in a community, secondary-level lithium-treated sample of patients.

METHODS

This was a cross-sectional study of the lithium-treated patients attending a general adult and an old age psychiatry service. Participants completed a 24-hour urine collection. Urine volume and the presence of polyuria were the outcomes of interest. The relationship between outcome and the participant's demographic and clinical characteristics was explored with univariable and multivariable analysis.

RESULTS

A total of 122 participants were included in the analysis, with 38% being diagnosed with polyuria. Female gender and increased body weight independently predicted the presence of polyuria (standardized regression coefficient 1.01 and 0.94, respectively; p = 0.002 and p = 0.003, respectively). Female gender and increased body weight, lithium dose, and duration of lithium treatment independently predicted higher 24-hour urine volumes (standardized regression coefficients 0.693, p < 0.0005; 0.791, p < 0.0005; 0.276, p = 0.043; 0.181, p = 0.034, respectively). Of three different weight metrics, lean body weight was the most predictive.

CONCLUSIONS

Female gender and increased body weight explain part of the variance of this adverse effect. Both risk factors offer fresh insights into the pathophysiology of this potentially reversible and dangerous adverse effect of lithium treatment. Future research should focus on understanding the differences between the genders and between different body compositions in terms of lithium pharmacokinetics and pharmacodynamics.

The McGill Geriatric Lithium-Induced Diabetes Insipidus Clinical Study (McGLIDICS)

OBJECTIVE

Despite being a common and potentially serious condition, nephrogenic diabetes insipidus (NDI) remains poorly understood in older lithium users. Our main objective was to compare the prevalence of NDI symptoms and decreased urine osmolality ([UOsm] < 300 milli-Osmoles [mOsm/kg]) among geriatric and adult lithium users. We also assessed NDI symptoms, serum sodium (Na+), and urine specific gravity (USG) as possible surrogate measures of decreased UOsm, and ascertained whether potential etiologic factors independently correlated with decreased UOsm.

METHOD

This was a cross-sectional study of 100 consecutive outpatients treated with lithium from 6 tertiary care clinics, of which 45 were geriatric (aged 65 years and older) and 55 adult (aged 18 to 64 years). Patients completed a symptom questionnaire and underwent laboratory tests, including UOsm, serum Na+, and USG.

RESULTS

Geriatric and adult lithium users had similar rates of decreased UOsm (12.5%, compared with 17.9%, P = 0.74), but geriatric patients reported less symptoms (P < 0.05). Although UOsm did not correlate with symptoms or current serum Na+, USG of less than 1.010 was suggestive of UOsm of less than 300 mOsm/kg. Age, lithium duration, and serum lithium level were independently associated with UOsm.

CONCLUSIONS

The prevalence of decreased UOsm is similar in geriatric and adult lithium users, but older patients are less likely to report urinary and thirst symptoms. Although subjective symptoms do not correlate with UOsm, USG may be a cost-efficient clinical surrogate measure for UOsm. We suggest clinicians increase their vigilance for decreased UOsm, especially in lithium users with advanced age, longer duration of lithium exposure, and higher lithium levels. This may potentially prevent lithium intoxication, falls, hypernatremic events, and renal dysfunction.

The effects of lithium on renal function in older adults--a systematic review

Chronic renal failure (CRF) and nephrogenic diabetes insipidus (NDI) are potential consequences of chronic lithium use, while acute renal failure (ARF) has been described in lithium intoxication. We performed a systematic review of all studies pertaining to the effects of lithium on the kidney in older adults. The ARF incidence was 1.5% per person-year and concurrent loop diuretic and angiotensin-converting enzyme inhibitor use with lithium increased the risk. The CRF prevalence estimates varied from 1.2% to 34%, with risk factors including age, previous lithium intoxication, polyuria, previously impaired renal function, and decreased maximal urine osmolality. The prevalence of NDI varied widely from 1.8%  to 85%. Risk factors included lithium duration, dose, level, slow-release formulation, and clinical nonresponse. Except for amiloride use in NDI, there is little evidence for treatment of other lithium-induced adverse renal effects. Currently, there is no compelling evidence to suggest that lithium should be avoided in elderly patients for fear of renal side effects.

Lithium-induced renal insufficiency: a longitudinal study of creatinine increases in intellectually disabled adults

BACKGROUND

Lithium has been shown to increase serum creatinine levels in a subgroup of patients. However, lithium-induced increases in serum creatinine have not been well studied with regard to timing, trajectory, or predictability.

METHODS

The medical records of 16 intellectually disabled individuals treated with lithium between 1980 and 2010 in whom serum creatinine levels peaked at 1.5 mg/100 mL or higher (ie, who developed renal insufficiency) were reviewed. These individuals were compared with a group of 36 similar lithium-treated individuals in whom serum creatinine did not reach 1.5 mg/100 mL.

RESULTS

The 16 lithium-treated individuals who developed renal insufficiency had a mean peak serum creatinine level of 1.8 ± 0.3 mg/100 mL while on lithium. The mean time from institution of lithium until the 1.5 mg/100 mL serum creatinine level was first reached was 7.9 years. After lithium was discontinued, overall mean serum creatinine levels did not significantly change. Reaching a serum creatinine level of 1.3 or 1.4 mg/100 mL predicted reaching a 1.5 mg/100 mL level or higher. No significant differences in the age lithium was started, baseline serum creatinine levels, years receiving lithium, sex, or race differentiated those who developed renal insufficiency.

CONCLUSIONS

Prescribing lithium led to elevated serum creatinine levels in some individuals. A serum creatinine level of 1.3 and/or 1.4 mg/100 mL predicted renal insufficiency. Clinical implications of this study are that if 1 serum creatinine result reaches 1.3 mg/100 mL or more, intensive monitoring for further increases is indicated.

Effects of chronic lithium treatment on renal function

INTRODUCTION

Lithium treatment is associated with renal side effects which vary from mild nephrogenic diabetes insipidus to end stage renal disease (ESRD). A review of the literature suggests that ESRD is a very rare side effect, caused after very long-term lithium treatment, and that it might be preventable if lithium is stopped early.

METHODS

Sixty-one patients were treated with lithium for a mean of 15.6 years (range 3-32, SD=6.4). Their kidney function was monitored at an Affective Disorders Clinic for a mean of 11.5 years (range 2-29, SD=5.4). We estimated their glomerular filtration rate (eGFR) at the end of monitoring. As a control group we used 53 patients who received ECT at our hospital, and had not taken lithium, and nine patients from the same clinic who were taking other mood-stabilisers.

RESULTS

Lithium patients had lower eGFR compared to controls: 66.1 vs. 75.0 mL/min/1.73 m2, p=0.0006 after controlling for age and gender. The percentage of patients with an eGFR<60 ml/min/1.73 m2 (grade 3 chronic kidney disease) was 34.4%, vs. 13.1% in the controls, and was much increased compared to the general population in the respective age ranges. There was a modest but non-significant correlation between the number of years that patients had taken lithium and their eGFR, (beta=-0.177, B=-0.43, p=0.1). One patient reached an eGFR of 28 mL/min/1.73 m2 and her lithium was stopped. One patient required dialysis 6 years after leaving the clinic.

CONCLUSIONS

Lithium causes a modest decline in renal function. However the available research suggests that ESRD is a very rare complication of long-term lithium treatment, affecting ∼1% of patients who have taken lithium for over 15 years.

Meta-analysis of the effects of lithium usage on serum creatinine levels

There is conflicting evidence concerning lithium's effect on renal function. The aim is to clarify whether lithium affects kidney function and at what stage of treatment any effect may occur. Systematic review identified 23 studies split into three groups on which meta-analysis was performed to identify the following: A) lithium's effect on renal function in cross-sectional case-control studies, B) studies of renal function before and after commencement on lithium, C) studies of longer term effect in those already established on lithium therapy. Group A showed a statistically significant increase of 5.7 μmol/L in creatinine in the study population compared with controls. Group B showed a non-statistically significant rise in creatinine (2.9 μmol/L) after a mean follow-up of 86 months. Group C showed a statistically significant increase in creatinine of 7.0 μmol/L over a mean duration of 64 months. An increase in creatinine of an average of 1.6 μmol/L/year on lithium was also identified in this group. Any lithium-associated increase in serum creatinine is quantitatively small and of questionable clinical significance. However, routine renal function monitoring of patients on lithium is essential.

Lithium effect on renal glomerular function in individuals with intellectual disability

OBJECTIVE

The current study evaluated the effects of chronic administration of lithium on renal functioning in an intellectually disabled population.

METHODS

Fifty-seven lithium-treated individuals were compared with 24 behaviorally symptomatic controls using a retrospective chart review method. Serum creatinine levels and creatinine clearance activities were compared at baseline, at the time of peak creatinine levels, and at the end of the study in 2006.

RESULTS

The mean length of lithium administration was 8.76 years (range, 1-23 years). Chronic lithium administration yielded a significant increase in peak serum creatinine levels and a decrease in the corresponding creatinine clearance activity. Of the subjects, 22.8% had peak creatinine levels of 1.5 mg or higher per 100 mL (a common threshold for renal insufficiency). This contrasted with 0% (none) for the symptomatic control subjects (P = 0.008). In addition, 26.3% of the lithium-treated subjects had creatinine clearance activities less than 55 mL/min and 17.5% had less than 50 mL/min, both indicative of renal insufficiency, versus none of the symptomatic control subjects (P = 0.004 and P = 0.029, respectively). With lithium withdrawal, further deterioration of renal function did not occur in most cases, and many showed improvement, with decreases in serum creatinine levels and increases in creatinine clearance activity.

CONCLUSIONS

Chronic administration of lithium led to clinically significant increases in serum creatinine levels and decreases in creatinine clearance in lithium-treated intellectually disabled individuals.

Lithium treatment: are the present schedules optimal?

Lithium treatment is a proven and effective prophylactic treatment of bipolar affective disorders. To day patients receive their lithium in one or two daily doses, and the dosage level in the individual patient is adjusted to the lowest possible level in order to reduce side effects. In the present article we suggest an alternative treatment strategy also aiming at reducing side effects but not involving the slow process of finding the lowest possible effective lithium dose. We suggest prophylaxis may be obtained by giving lithium every second day in a dose producing 12 hour serum lithium concentrations between 0.6 and 0.9 mM, and leading to very low lithium concentrations every second day. This treatment schedule is at present being tested in the clinic.

Effects of short- and long-term lithium treatment on kidney functioning in patients with bipolar mood disorder

Lithium (Li) carbonate has been reported to be able to cause some reversible functional changes in the kidney. In this study, the authors aimed to investigate whether the duration of Li treatment is the primary determinant of the changes in renal functioning due to the Li treatment. For this purpose, 10 Li-naïve (mean age+/-S.D.: 34.50+/-4.85), 10 short-term (mean age+/-S.D.: 31.77+/-7.61) and 10 long-term (mean age+/-S.D.: 36.60+/-10.15) Li-treated bipolar patients were included in the study. Serum blood urea nitrogen (BUN) and creatinine, urine creatinine levels, creatinine clearance, urine osmolality before and after 8-h water deprivation and urine osmolality after desmopressin injection were measured in all patients. Serum BUN and creatinine levels were within the normal limits and not statistically different among the groups. Creatinine clearance of the long-term Li-treated group was significantly lower than both that of the Li-naïve group and that of the short-term Li-treated group. After 8-h water deprivation and also after desmopressin injection, no difference was found among the groups in terms of urine osmolality. However, when each patient was evaluated individually in terms of their renal concentrating ability, partial nephrogenic diabetes insipidus was diagnosed in four patients on long-term and in two patients on short-term Li treatment. To our surprise, hypothalamic diabetes insipidus was also diagnosed in other two patients on long-term Li treatment. These results demonstrate that long-term Li treatment may cause impairment in renal concentrating ability, some of which may originate from the effects of Li on vasopressin on hypothalamic level, and a decrease in glomerular filtration rate (GFR). In the light of these data, we can conclude that long-term administration of Li may be a risk factor for Li-induced renal impairment, which is a progressive effect in nature.

Aquaporin-2 as a biomarker of distal renal tubular function using lithium as an experimental model

Aquaporin-2 protein levels can be detected in the urine of normal of subjects if measured after fluid deprivation. By contrast, in patients with nephrogenic diabetes insipidus caused by mutations in the aquaporin-2 gene, urine aquaporin-2 protein excretion cannot be detected. We propose that properly standardized measurements of urinary aquaporin-2 protein may provide a useful biomarker of distal tubular function in a variety of acquired conditions that impair concentrating ability including some nephrotoxic agents.

Lithium and the kidney: an updated review

Despite the availability of alternative agents, lithium continues to be the standard against which all mood stabilisers, prescribed for acute and maintenance treatment of bipolar (and, to a lesser extent, unipolar) mood disorders, are compared. As a medication often used on a maintenance basis for a lifelong disorder, the potential for lithium to cause long term organ toxicity has generated appropriate concern. Foremost among these concerns are its renal effects. Lithium adversely affects renal tubular function, causing polyuria secondary to a deficit in urine concentrating ability. This effect is probably progressive for the first decade of lithium therapy, i.e. it correlates with duration of lithium therapy. Although this effect of lithium is probably functional and reversible early in treatment, it may become structural and irreversible over time. In contrast, the effect of lithium on glomerular function is not progressive. Conclusions in this area are hampered by the evidence that patients with psychiatric disorders who are not receiving lithium also show defects in certain aspects of renal function. Despite the generally sanguine data on glomerular function, a very small group of patients may develop renal insufficiency due to lithium (possibly in conjunction with other somatic factors) in the form of interstitial nephritis. However, for the vast majority of patients, the renal effects of lithium are benign. Current strategies for minimising the renal effects of lithium include: (i) assiduously avoiding episodes of renal toxicity; (ii) monitoring serum lithium concentrations in order to achieve optimal efficacy at the lowest possible concentration; (iii) monitoring serum creatinine levels on a yearly basis, getting further medical evaluation when the serum creatinine level consistently rises above 140 mmol/L (1.6 mg/dl); and (iv) possibly administering lithium once a day.

Assessment and treatment of bipolar disorder in the elderly

The aetiology of late-onset bipolar disorder is heterogeneous because the disease is more likely to have a secondary (i.e. a medical disorder or medication-induced) cause in older than in younger patients. Elderly patients with bipolar disorder typically require lithium dosages that are 25 to 50% lower than those used in younger individuals. Information on the use of valproic acid (sodium valproate) in elderly patients with bipolar disorder is limited but encouraging. In contrast, there is virtually no information regarding the use of carbamazepine or other drugs in this patient group. Electroconvulsive therapy is well tolerated by older people and can be useful for these patients.

Clinical relevance of drug interactions with lithium

Although lithium continues to be regarded as the treatment of choice for bipolar disorders, the clinical use of this mood stabiliser is associated with an extremely narrow therapeutic range. Relatively minor increases in serum concentrations may induce serious adverse sequelae, and concentrations within the therapeutic range may result in toxic reactions. The safety of combining lithium with other medications, therefore, is a major concern, and extensive clinical experience has served to identify several significant drug interactions. Lithium removal from the body is achieved almost exclusively via renal means. As a result, any medication that alters glomerular filtration rates or affects electrolyte exchange in the nephron may influence the pharmacokinetic disposition of lithium. Concomitant use of diuretics has long been associated with the development of lithium toxicity, but the risk of significant interactions varies with the site of pharmacological action of the diuretic in the renal tubule. Thiazide diuretics have demonstrated the greatest potential to increase lithium concentrations, with a 25 to 40% increase in concentrations often evident after initiation of therapy. Osmotic diuretics and methyl xanthines appear to have the opposite effect on lithium clearance and have been advocated historically as antidotes for lithium toxicity. Loop diuretics and potassium-sparing agents have minor variable effects. Nonsteroidal anti-inflammatory drugs (NSAIDs) have also been associated with lithium toxicity, although the relative interactive potential of specific NSAIDs is difficult to determine. Small prospective studies have demonstrated large interindividual differences in lithium clearance values associated with different NSAIDs. A growing body of evidence also suggests that ACE inhibitors may impair lithium elimination, but further investigations are needed to identify patients at risk. Anecdotal reports have linked numerous medications with the development of neurotoxicity without an apparent effect on the pharmacokinetic disposition of lithium. Antipsychotics, anticonvulsants and calcium antagonists have all be implicated in a sufficient number of case reports to warrant concern. As these medications have all been commonly coadministered with lithium, the relative risk of serious interactions appears to be quite low, but caution is advised.

Lithium prophylaxis of manic-depressive disorder: daily lithium dosing schedule versus every second day

The prophylactic efficacy of lithium carbonate given every second day versus daily intake was compared in a double-blind study including 50 manic-depressive patients. The patients met the DSM-III-R criteria for bipolar disorder or depressive disorder; according to ICD-8 the patients fulfilled criteria for manic-depressive disorder: All patients had experienced at least 3 episodes of mania or major depression, and all had been euthymic for at least 4 months. The median doses of lithium carbonate given were 800 mg/day or 1200 mg/every second day corresponding to median 12-h serum lithium concentrations of 0.6 mmol/l or 0.7 mmol/l, respectively. Manic or depressive relapse was defined as DSM-III-R criteria for mania or major depression, and a score > or = 10 on the Bech-Rafaelsen Mania Scale or the Bech-Rafaelsen Melancholia Scale, respectively. The two treatment schedules were allocated at random. Using the Cox proportional hazard model for statistical analysis, the lithium dosing schedule of every second day did not maintain its prophylactic efficacy against recurrent episodes of manic-depressive disorder. The risk of relapse increased 3 times when the interval between intake of lithium was extended from 1 to 2 days.

Nephrotoxicity of xenobiotics

Nephrotoxicity can be grouped by the xenobiotics place of action, by the clinical presentation or by the generic toxic effect. The latter can be dose related, indirect, idiosyncratic or allergic. Nephrotoxicity of lithium, demeclocycline, aminoglycosides, cyclosporine, mercuric ion, nonsteroidal anti-inflammatory drugs, methoxyflurane, ethylene glycol, D-penicillamine and methicillin is reviewed in light of all these three viewpoints, but emphasis is on toxic mechanisms.

A cross-sectional study of glomerular function in 740 unselected lithium patients

Creatinine clearance was estimated using a formulaic method from serum creatinine, age and sex in 740 unselected lithium-treated patients in southeastern Scotland. Psychiatric history and details of prescribing and monitoring of lithium treatment were obtained from existing case registers. Lithium treatment duration and glomerular filtration, controlling for the effects of age, were weakly related, but only in males. Cases who had been exposed to higher serum lithium concentrations had lower creatinine clearance than those maintained within therapeutic range. Of cases within the lowest quartile of renal function, proportionally more were supervised in general practice rather than at hospital clinics. Suggestions are made for the clinical practice of monitoring serum lithium concentrations and serum creatinine.

Kidney functioning during lithium treatment: a prospective study of patients treated with lithium for up to ten years

A cohort of 53 patients with affective disorders who originally carried through renal functional tests before start of prophylactic lithium treatment were followed up prospectively after an average period of 8.5 years (range 7-10 years). Ten patients who had continued lithium treatment were re-examined. In this subgroup, the glomerular function was unaffected by the treatment, whereas the average urine volume increased during lithium treatment (NS). Polyuria and low renal concentrating abilities were also found before start of treatment and these findings underline the importance of access to renal baseline information prior to lithium treatment.

Lithium: long-term effects on the kidney. A prospective follow-up study ten years after kidney biopsy

Forty-six patients with recurrent affective disorders, who began prophylactic treatment with lithium an average of 20 years previously, were followed up prospectively after a ten-year observation period to assess renal function. Nineteen patients had maintained lithium therapy, and eight patients had died. Tubular function was almost unchanged and patients who had continued lithium had not shown increasing urine volumes, but patients who had received lithium in a single daily dosage at night had a significantly lower urinary output than those on a multiple-dosage schedule. The GFR decreased significantly, but the decline was essentially dependent on increasing age, except in two patients who had developed renal insufficiency. Renal function during chronic lithium treatment is related to age, lithium intoxication episodes, pre-existing renal disease, and treatment schedule rather than to duration of prophylactic lithium therapy.

Renal function in chronic lithium-treated patients

We investigated the renal function (urine volume, glomerular filtration rate, urinary osmolality and proteinuria) of 50 patients chronically treated with lithium carbonate for major affective disorder. No patient had any alteration in the parameters considered. No relationship was found between any of the parameters studied and duration of illness or lithium levels, both in serum and red blood cells. These results were confirmed by the administration of the DDAVP test to 10 patients of the original sample; no alteration of concentration ability was found. We suggest that the discrepancy between our findings and those of most authors was a result of the serum lithium level of our patient sample, which was lower than that usually used in other studies.

Risk factors for toxic nephropathies

The best definition of risk factors for renal injury, irrespective of the aetiological agent, comes from observations in patients with acute renal failure. From such observations, two subdivisions have evolved, i.e., acute insults and host risk factors. Acute renal insults include: hypertension, sepsis, use of nephrotoxic drugs (e.g., aminoglycoside antibiotics and contrast media), haemoglobinuria or myoglobinuria, liver disease and extracellular volume depletion. Host risk factors include: advanced age, hypertension, gout and hyperuricaemia, diabetes mellitus, chronic renal failure and use of diuretics. Furthermore, the mechanism of acute renal injury can be correlated with different risk factors: for a tubular toxic agent, acting either directly on the cells or haemodynamically, a dose-dependency is characteristic; while for immunologically mediated injury, genetic predisposition is more important. The identification of risk factors for chronic toxic injury is confounded by the possibilities of multiple episodes of subclinical renal injury, the distinct possibility that a major component of the ageing process may be a loss of renal reserve, and a progressive body burden, of, e.g., cadmium, which may deplete intrinsic protective mechanisms. However, clinically relevant risk factors can alert the clinician to exercise additional caution when prescribing medications that are potentially nephrotoxic. Such factors include dehydration, pre-existing renal disease, age, co-existing diseases that cause renal ischaemia, gender, concomitantly administered drugs, and electrolyte abnormalities.

Elevation of the renal enzyme N-acetyl-beta-glucosaminidase in affectively disordered patients

A minority of patients with affective disorders experience mild elevations of the renal enzyme N-acetyl-beta-glucosaminidase (NAG). Some affectively disordered patients also have reduced concentrating ability and reduced creatinine clearance. Thirty-one affectively disordered patients were compared to 17 healthy controls, to evaluate whether these various renal abnormalities are associated with one another and to further examine the proportion of affectively disordered patients experiencing NAG elevations. Twenty-nine percent of patients had an elevated NAG, whereas none of the controls did (P less than .005). There was a trend for an association between elevated NAGs and reduced creatinine clearance (P less than .08), but no association was found between concentrating ability and either elevated NAG or reduced creatinine clearance.

Prevalence, pathogenesis, and treatment of renal dysfunction associated with chronic lithium therapy

From the analysis of several studies published from 1979 to 1986 comprising 1,172 patients, we estimated that glomerular filtration rate (GFR) was normal in 85% of unselected patients on chronic lithium therapy. The remaining 15% of patients displayed only mild reduction in GFR, clustering at approximately 60 mL/min. Thus, the data available to date do not support earlier concerns that long-term lithium therapy could eventuate into renal insufficiency. The most prevalent renal effect of lithium is impairment of concentrating ability, which we estimated to be present in at least 54% of 1,105 unselected patients on chronic lithium therapy. This defect translated into overt polyuria in only 19% of unselected cases. A renal lesion confined to the collecting tubule has been described in humans who have taken lithium for short periods of time. This lesion may represent the collecting tubule's response to the intracellular accumulation of lithium, which interferes with cAMP formation and results in an early and probably reversible inhibition of antidiuretic hormone (ADH)-mediated water transport. However, long-term lithium therapy may induce a progressive and partly irreversible defect in concentrating ability. The potential risk for dehydration associated with lithium-induced polyuria, as well as the discomfort inherent to this side effect, deserves evaluation and consideration for therapeutic intervention. Amiloride has additional advantages over conventional treatment of nephrogenic diabetes insipidus using thiazide diuretics. The action of amiloride on ADH-mediated water transport seems specific in as much as it is capable of preventing the uptake of lithium in high resistance epithelia and thereby prevents the inhibitory effect of intracellular lithium on water transport. Unlike thiazides, amiloride has a weak natriuretic effect and is less likely to increase plasma lithium levels by causing volume contraction. In addition, amiloride, by conserving potassium, obviates the need for potassium supplementation that is usually required to prevent hypokalemia when thiazides are used to treat lithium-induced polyuria. Since amiloride may prevent chronic intracellular lithium accumulation in the collecting tubule, future studies should elucidate whether amiloride also has a role in preventing lithium-induced chronic tubulo-interstitial damage.

Lithium in depression: a review of the antidepressant and prophylactic effects of lithium

The therapeutic effects of lithium in depression are reviewed. The acute antidepressant effect of lithium alone is neither as impressive nor as predictable as its antimanic action, nor is it equivalent to that of tricyclic antidepressants. In patients who are 'refractory' to tricyclics or monoamine oxidase inhibitors, combined treatment with lithium may augment antidepressant response. Lithium is an effective prophylactic treatment in both unipolar and bipolar disorder and in the latter is the drug of choice. Aspects of monitoring, such as range of therapeutic plasma levels, dosage regimen and adverse effects, are discussed. Current evidence suggests that, in patients who fail to respond to lithium or are unable to tolerate side-effects, carbamazepine should be considered.

Lithium: long-term effects on the kidney. I. Renal function in retrospect

46 patients treated with lithium for an average of 8 years participated in a functional-morphological follow-up study based on a 12-day hospitalization and involving a kidney biopsy. The functional part of the study showed that tubular function was markedly influenced, leading to increased urine volume (average 3 1/24 h) and a decreased renal concentration capacity in 85% of the patients. Glomerular function was generally not influenced, and only 10% of the patients had glomerular filtration rates below their age-corrected normal ranges. Both urine volume and glomerular filtration rates showed significant correlations with dosage schedule. Urine volume was lower and glomerular filtration rate higher on a one-dose schedule than when lithium was given in divided doses during the day. It is concluded that discontinuity in lithium treatment minimizes lithium effects on kidney function.