Renal concentrating capacity in long-term lithium treatment and after withdrawal of lithium

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.

[Renal toxicity of lithium]

Besides its efficiency, lithium has a narrow therapeutic index and can result in considerable toxicity. Among the potential side effects, two types of renal toxicity are observed: a decreased renal concentrating ability and a chronic renal failure. Lithium-induced polyuria is frequent, estimated to affect up to 40% of patients, and develops usually early. It may be irreversible, especially if the treatment has been prescribed for more than 15 years. A chronic renal failure is observed in patients treated for more than 10 to 20 years. Its prevalence is estimated at 12% after 19 years of treatment. Some patients (0.5%) may reach end stage renal disease. The major risk factor is the duration of exposure to lithium. Discussion about stopping or not lithium in case of renal failure needs multidisciplinary expertise and depends on psychiatric status and renal function.

Electrocardiographic changes caused by lithium intoxication in an elderly patient

Lithium intoxication can cause serious cardiac toxicity and is associated with electrocardiogram (ECG) changes. This paper described a case of a 76-year-old man who was lithium intoxicated and showed a variety of ECG abnormalities including sinus bradycardia, rapid atrial fibrillation, second-degree atrioventricular block and T wave changes. We monitored his ECGs during the after 3 days consecutively. After hemodialysis, his ECG abnormalities partially eased along with his serum lithium concentration decreased.

Lithium nephrotoxicity

Reports of toxic effects on the kidney of lithium treatment emerged very soon after lithium therapy was introduced. Lithium-induced nephrogenic diabetes insipidus is usually self-limiting or not clinically dangerous. Some reports of irreversible chronic kidney disease and renal failure were difficult to attribute to lithium treatment since chronic kidney disease and renal failure exist in the population at large. In recent years, large-scale epidemiological studies have convincingly shown that lithium treatment elevates the risk of chronic kidney disease and renal failure. Most patients do not experience renal side effects. The most common side effect of polyuria only weakly predicts increasing creatinine or reduced kidney function. Among those patients who do experience decrease in creatinine clearance, some may require continuation of lithium treatment even as their creatinine increases. Other patients may be able to switch to a different mood stabilizer medication, but kidney function may continue to deteriorate even after lithium cessation. Most, but not all, evidence today recommends using a lower lithium plasma level target for long-term maintenance and thereby reducing risks of severe nephrotoxicity.

Chronic renal failure in lithium-using geriatric patients: effects of lithium continuation versus discontinuation--a 60-month retrospective study

OBJECTIVE

Lithium remains an important treatment in bipolar disorder. Although lithium is often discontinued because of signs of renal failure, it is unclear if this alters the course of renal function in the majority of patients. We hypothesize that in geriatric patients with chronic renal failure (CRF), who have a high burden of medical illness, lithium continuation does not significantly impact renal function (glomerular filtration rate (eGFR)).

METHODS

We conducted a retrospective study of tertiary-care geriatric psychiatry outpatients with a history of lithium use and evidence of CRF (eGFR ≤ 60 ml/min/1.73 m2 on ≥ 2 occasions in ≥ 3 months). The 27 patients who met these criteria were divided into lithium 'continuers' (continued use ≥ 2 years following CRF) and 'discontinuers'. Mean eGFR and creatinine were followed at 21 and 60 months after developing CRF.

RESULTS

Mean serum eGFR and creatinine were not significantly different between groups at any time during follow-up. When comparing renal function at 60 months to baseline, a trend towards increased creatinine was seen in continuers (p = 0.06) but not in discontinuers. Changes in eGFR in continuers and discontinuers after 60 months did not achieve statistical significance (p = 0.35 and 0.98). However, clinically important decreases in eGFR occurred in the majority of continuers but in none of the discontinuers.

CONCLUSIONS

There was a trend towards declining renal function in lithium continuers at 60-month follow-up. Future prospective longitudinal studies will be needed to confirm our findings. We suggest vigilance and close monitoring of renal function when continuing CRF patients on lithium for extended periods.

Expression of transporters involved in urine concentration recovers differently after cessation of lithium treatment

Patients receiving lithium therapy, an effective treatment for bipolar disorder, often present with acquired nephrogenic diabetes insipidus. The nephrotoxic effects of lithium can be detected 3 wk after the start of treatment and many of these symptoms may disappear in a few weeks after lithium use is stopped. Most patients, however, still have a urine-concentrating defect years after ending treatment. This prompted an investigation of the transporters involved in the urine concentration mechanism, UT-A1, UT-A3, aquaporin-2 (AQP2), and NKCC2, after discontinuing lithium therapy. Sprague-Dawley rats fed a Li2CO3-supplemented diet produced large volumes of dilute urine after 14 days. After lithium treatment was discontinued, urine osmolality returned to normal within 14 days but urine volume and urine urea failed to reach basal levels. Western blot and immunohistochemical analyses revealed that both urea transporters UT-A1 and UT-A3 were reduced at 7 and 14 days of lithium treatment and both transporters recovered to basal levels 14 days after discontinuing lithium administration. Similar analyses demonstrated a decrease in AQP2 expression after 7 and 14 days of lithium therapy. AQP2 expression increased over the 7 and 14 days following the cessation of lithium but failed to recover to normal levels. NKCC2 expression was unaltered during the 14-day lithium regimen but did increase 14 days after the treatment was stopped. In summary, the rapid restoration of UT-A1 and UT-A3 as well as the increased expression of NKCC2 are critical components to the reestablishment of urine concentration after lithium treatment.

The International Society for Bipolar Disorders (ISBD) consensus guidelines for the safety monitoring of bipolar disorder treatments

OBJECTIVES

Safety monitoring is an important aspect of bipolar disorder treatment, as mood-stabilising medications have potentially serious side effects, some of which may also aggravate existing medical comorbidities. This paper sets out the International Society for Bipolar Disorders (ISBD) guidelines for the safety monitoring of widely used agents in the treatment of bipolar disorder. These guidelines aim to provide recommendations that take into consideration the balance between safety and cost-effectiveness, to highlight iatrogenic and preventive clinical issues, and to facilitate the broad implementation of therapeutic safety monitoring as a standard component of treatment for bipolar disorder.

METHODS

These guidelines were developed by an ISBD workgroup, headed by the senior author (MB), through an iterative process of serial consensus-based revisions. After this, feedback from a multidisciplinary group of health professionals on the applicability of these guidelines was sought to develop the final recommendations.

RESULTS

General safety monitoring recommendations for all bipolar disorder patients receiving treatment and specific monitoring recommendations for individual agents are outlined.

CONCLUSIONS

These guidelines are derived from evolving and often indirect data, with minimal empirical cost-effectiveness data available to provide guidance. These guidelines will therefore need to be modified to adapt to different clinical settings and health resources. Clinical acumen and vigilance remain critical ingredients for safe treatment practice.

Renal function and morphology in long-term lithium and combined lithium-neuroleptic treatment

Ten patients on long-term lithium therapy and ten on lithium and neuroleptics (combination therapy) were examined with renal biopsy and tests of renal function. Patients on combination therapy had more pronounced histopathological changes and lower concentrating capacity than patients on lithium alone. Patients on combination therapy had received a larger total dose of lithium and had had higher maximum serum lithium levels than patients on lithium alone. Patients with large daily urine volumes had a low concentrating capacity. There was a negative correlation between degree of histopathological lesions and urinary concentrating capacity. Estimation of urinary concentrating capacity seems to be of value for the assessment of renal lesions in lithium treatment.

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.

Changes in cellular composition of kidney collecting duct cells in rats with lithium-induced NDI

Lithium treatment for 4 wk caused severe polyuria, dramatic downregulation in aquaporin-2 (AQP-2) expression, and marked decrease in AQP-2 immunoreactivity with the appearance of a large number of cells without AQP-2 labeling in the collecting ducts after lithium treatment. Surprisingly, this was not all due to an increase in AQP-2-negative principal cells, because double immunolabeling revealed that the majority of the AQP-2-negative cells displayed [H(+)]ATPase labeling, which identified them as intercalated cells. Moreover, multiple [H(+)]ATPase-labeled cells were adjacent, which was never seen in control rats. Quantitation confirmed a significant decrease in the fraction of collecting duct cells that exhibited detectable AQP-2 labeling compared with control rats: in cortical collecting ducts, 40 +/- 3.4 vs. 62 +/- 1.8% of controls (P < 0.05; n = 4) and in inner medullary collecting ducts, 58 +/- 1.6 vs. 81 +/- 1.3% of controls (P < 0.05; n = 4). In parallel, a significant increase in the fraction of intercalated ([H(+)]ATPase-positive) cells was shown. Urine output, whole kidney AQP-2 expression, cellular organization, and the fractions of principal and intercalated cells in cortex and inner medulla returned to control levels after 4 wk on a lithium-free diet following 4 wk on a lithium-containing diet. In conclusion, lithium treatment not only decreased AQP-2 expression, but dramatically and reversibly reduced the fraction of principal cells and altered the cellular organization in collecting ducts. These effects are likely to be important in lithium-induced nephrogenic diabetes insipidus.

A historical cohort study of kidney damage in long-term lithium patients: continued surveillance needed

BACKGROUND

Insufficient knowledge on the longitudinal fate of renal function in lithium patients incited this retrospective study of 149 patients.

METHOD

Medical record review of a lithium cohort (N = 149), 8--12 years after an initial renal function study.

RESULTS

Twenty-one patients had died, one from uremia probably not caused by lithium, and 42 had discontinued lithium. Reduced urinary concentrating capacity (Umax) or glomerular filtration rate (GFR) was not more frequent among deceased or off-lithium patients than among the 86 patients who were on lithium at follow-up. In 63 of the latter patients, Umax had been re-examined after the initial study, and GFR in 29 patients. Reduced Umax and GFR had become twice as common, and average Umax and GFR had decreased significantly. The reduction of GFR was associated with lithium treatment duration and age, and reduced Umax with treatment duration only.

CONCLUSIONS

Reduced renal function is not a major cause of treatment discontinuation but becomes increasingly common with treatment duration.Limitations. Missing data rendered the interpretation difficult in some respects. Clinical relevance. The increased proportion of patients with reduced GFR and Umax with time implies an increased risk of potentially lethal dehydration and lithium intoxication. Continued surveillance of urinary output and GFR is therefore necessary.

Lithium revisited

OBJECTIVE

To review lithium's utility in the treatment of mood disorders.

METHOD

We reviewed the safety, tolerability, teratogenicity, optimal dosing regimens, and mortality-lowering effects of lithium. Clinical relevance and scientific rigour determined which articles we selected for review.

RESULTS

Lithium is the paradigmatic treatment for bipolar disorder (BD). In treating BD, optimal maintenance plasma levels may be approximately 0.75 to 0.85 mEq/L. Although nephrogenic diabetes insipidus is not uncommon, irreversible renal failure due to lithium appears to be a rare, idiosyncratic event. Lithium-induced cardiovascular teratology appears to be less common than previously thought. Optimal lithium dosing may be once daily, this agent appears to bestow a robust suicide-lowering effect, and emerging data hint at neurotrophic and neuroprotective effects.

CONCLUSION

Lithium remains an effective and integral agent in the treatment of BD. Its ability to lower suicide rates in persons with BD warrants clinical attention.

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.

Emergency treatment of lithium-induced diabetes insipidus with nonsteroidal anti-inflammatory drugs

Thiazides and amiloride are the most often suggested treatment for nephrogenic diabetic insipidus. We found this ineffectual in a patient with acute problems and reviewed the literature to see if there were other more efficient approaches. A 47-year-old woman on lithium had polyuria. When inadvertently fasted for 48 h she became confused, had a seizure, and her sodium was 170 mmol/L. Urinary output was 24 L/day. Large volumes of intravenous fluids were given but sodium remained > 170 mmol/L. Treatment with DDAVP, thiazides, and amiloride did not decrease urinary output. Indomethacin 150 mg was started and urine volume immediately fell to one-half. However, because of persistent high urine output the patient was then fluid depleted, with further reduction to normal in urine volume, and Na decreased to 140 mmol/L. Creatinine rose from 135 mumol/L to 173 mumol/L, but decreased to 152 mumol/L when indomethacin was decreased to 75 mg q.d.; urinary output remained stable around 2 L/day. The literature described 22 patients with nephrogenic diabetes insipidus (16 congenital, 6 lithium) treated with nonsteroidal anti-inflammatory drugs. Urine flow was reduced to 1/3, within hours. Rarely, mild renal failure ensued, improving in all but one case when nonsteroidal anti-inflammatory drugs were reduced. Indomethacin (and controlled volume reduction if continued high urine output), while observing renal function, appears the emergency treatment of choice for serious complications of nephrogenic diabetes insipidus.

Evidence of lipoperoxidation induced by lactic acid on kidney homogenates

Sawas and Gilbert (Arch. Int. Pharmacodyn. Ther., 276 (1985) 301-312) reported that the commercial solution of haloperidol induces lipoperoxidation of kidney homogenates from Sprague-Dawley rats. However, it would appear that this effect is attributable to the excipient, lactic acid, rather than to haloperidol itself. Lactic acid enhances susceptibility to lipoperoxidation of kidney homogenates in a dose- and time-dependent manner by increasing production of thiobarbituric acid-reactive substances and slightly decreasing polyunsaturated fatty acids such as arachidonic acid and docosahexaenoic acid. This stimulation of lipoperoxidation may be attributed to a mechanism less dependent on enzymatic action than on Fe2+ and Fe3+. Lactic acid may facilitate iron release and formation of iron complexes, factors which increase susceptibility to oxidative stress.

Lithium intoxication: a coordinated treatment approach

This case illustrates the clinical features of lithium intoxication and the problems in treating it that may arise as a result of lithium's effects on the kidney. It also demonstrates the difficulties that can develop when a delicate physiologic balance is inadvertently disrupted by nonpharmacologic interventions such as seclusion and consequent restriction of access to food and water. Patients with lithium-induced urine-concentrating defects are especially at risk for dehydration, and care must be taken to ensure adequate fluid and salt intake. This case also shows how intense negative feelings evoked by chronically mentally ill patients can adversely affect their psychiatric and medical care. While such feelings are inevitable, their impact may be lessened by improved communication and coordination between the medical and psychiatric systems of care and by the presence of psychiatrists in the general medical hospital.

The use of lithium in the medically ill

Many patients taking lithium for the treatment of mood disorders suffer from concomitant medical illnesses. Because of its effects on multiple organ systems, extra caution is required when lithium is used in the presence of medical illness. Available data regarding the use of lithium in the presence of thyroid, renal, cardiovascular, dermatologic, and respiratory disease as well as in the presence of disorders of glucose and calcium metabolism are reviewed. In addition, recommendations regarding safe use, serum monitoring, and potential drug interactions are discussed.

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: long-term effects on the kidney. IV. Renal lithium clearance

Renal lithium clearance was investigated in 44 patients treated with lithium for an average of 8 years as part of a functional-morphological follow-up study including a kidney biopsy. The average renal lithium clearance was 0.36 ml/s (= 21.6 ml/min). A significant correlation with age, sex and glomerular filtration rate was seen, whereas no significant relationship with urine volume, lithium treatment regimen and histopathological biopsy variables was found. The results were compared with the same renal functional tests obtained from a control group consisting of 26 patients with affective disorders never treated with lithium. The control group had a lower urine output, but no significant difference in lithium clearance was observed. In conclusion, renal lithium clearance is a specific investigation, which may provide valuable baseline information on glomerulo-tubular function in patients before and during prophylactic lithium treatment.

Lithium: long-term effects on the kidney. III. Prospective study

Renal function in 32 patients treated with lithium for an average period of 10 years was reexamined 2 years after the first examination. A markedly influenced tubular function leading to increased urine volume (average 3 litres/24 h) and decreased renal concentrating capacity was still found, whereas glomerular function remained unimpaired in nearly all of the patients. No statistically significant changes in renal functions were observed at the follow-up examination. The results were compared with the same renal functional tests obtained from a control group consisting of 53 patients with affective disorders never treated with lithium. The control group had a significantly lower urine output (average 2 litres/24 h), but lithium-treated patients on a one-dose schedule had an average urine volume of only 500 ml/24 h more than the controls. In conclusion, this prospective study found no evidence of a progressive impairment of glomerular or tubular function in lithium-treated patients reexamined after 2 years. Patients with affective disorders never treated with lithium had normal renal concentrating capacity.

The use of sodium and potassium to reduce toxicity and toxic side effects from lithium

Studies in rats find that the animals develop toxic side effects at serum levels which are therapeutic for man. Most of the toxic effects were prevented by feeding sodium and potassium. The rats must ingest and excrete comparatively higher amounts of lithium than humans to maintain these levels. Sodium used alone has been shown to reduce side effects in man, but was found to reduce therapeutic effectiveness at fixed lithium dosages. Evidence is presented to suggest that therapeutic effectiveness can be maintained and toxic side effects and risk of toxicity reduced, by using both sodium and potassium, and by modestly raising the dosage of lithium.

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.

Psychogenic polydipsia and water intoxication--concepts that have failed

Ten patients (8 men, 2 women; mean age 38.7 +/- 8.1 years), 7 of whom had schizophrenic disorders and 3 of whom had bipolar disorder (manic-depressive illness), manifested psychosis, intermittent hyponatremia, and polydipsia (PIP syndrome). The relationship between serum sodium and urinary water excretion among the 10 PIP patients is described in detail. The success of lithium in improving serum sodium levels and in decreasing urinary water excretion among the three PIP patients with bipolar disorder and the failure of changes in urinary water excretion to explain changes in serum sodium levels among the 10 PIP patients argue against "psychogenesis" as the explanation for the polydipsia and excessive water intake as the sole explanation for hyponatremia or complications ascribed to water intoxication.

Kidney function in a selected lithium population. A prospective, controlled, lithium-withdrawal study

Forty-six lithium (Li) patients who had been on Li for about 1-11 years were studied while on Li and after about 3 months (7 weeks-26 months) off Li. Kidney function was compared between patients on Li and the same patients off Li, and, in 32 matched pairs, between patients on and off Li and psychiatric controls. Urine osmolality (U-osmol) was significantly lower, urine volume higher in patients on Li than in controls. Measures of both glomerular and tubular function improved when Li-patients discontinued medication. U-osmol remained somewhat lower than in controls and was negatively correlated with time-on-Li. Although serum creatinine was somewhat higher in Li-patients off Li than in controls, clearance values were not different between the two groups. Long-term lithium treatment causes a permanent reduction of tubular function. Time-on-Li is a risk factor. In this population the reduction was clinically insignificant. In addition, Li treatment causes a reversible reduction of both tubular and glomerular function. The results can probably be generalized to other outpatient Li populations with the same time-on-Li and with U-osmol below 800 mOsm/kg during ongoing treatment.

Lithium and impairment of renal concentrating ability

In 19 patients on lithium maintenance therapy, impairment of renal concentrating ability was found to correlate with daily lithium dose. The correlation between dose and impaired renal concentrating ability was strongest for patients on regular lithium preparations and not significant for patients on a slow release preparation. In 2 patients with severe polyuria, renal concentrating ability increased markedly with thiazide treatment. No relationship between lithium dosing parameters and other side effects was found. These results emphasize the importance of dose and type of preparation of lithium in the production of renal side effects.

Clinical and laboratory effects of discontinuation of lithium prophylaxis

Twelve patients who met Research Diagnostic Criteria for a history of bipolar affective disorder gave informed consent for open discontinuation of lithium therapy for 3 weeks. There was no significant change after lithium discontinuation in the number of depressive or manic symptoms, in mood score, in total Zung Depression score, or in any of the 20 items found in the Zung Depression scale. There were significant reductions in total severity of side effects, and improvement in the three side effects reflecting renal function: polydipsia, polyuria, and nocturia. These changes were reflected in the significant increase in urine specific gravity. Significant changes in side effects did not take place until at least 2 weeks after lithium was discontinued. Other significant relationships were found between increases in serum thyroid hormone levels and in urine specific gravity, and decreases in Vmax of platelet serotonin uptake and increases in degree of clonidine-induced hypotension.

Side-effects of lithium at lower therapeutic levels: the significance of thirst

The prevalence of thirst, subjective polyuria and related side-effects was investigated in 87 patients attending a lithium clinic and in a group of 52 controls. Thirst was surprisingly common, occurring in 67% of patients, in spite of the fact that they had been maintained on relatively low levels of lithium, and was due principally to the lithium rather than to other psychotropic drugs. Urine flow and impaired renal water absorption correlated with the serum lithium level and the length of treatment in the patients, despite the fact that few were clinically polyuric. The pattern of the results confirms previous suggestions that lithium may stimulate the thirst mechanism directly as well as via an increased renal resistance to vasopressin. The possible implications in terms of clinical response are discussed.

Neuroleptics, lithium and renal function

Renal function test results in 26 patients on neuroleptic treatment, who had never received lithium or antidepressants, were compared with those in a matched group, treated with lithium; also, their tubular response to DDAVP was compared with that of 25 control subjects. Measurements of serum creatinine, creatinine clearance, and urinary albumin excretion showed no abnormality attributable to either neuroleptics or lithium. The maximum urine concentrating ability after DDAVP was significantly lower in the neuroleptic group than in controls, but significantly higher than in the lithium-treated patients. There was a significant correlation between excretion of urinary beta 2-microglobulin and duration of neuroleptic treatment, but mean excretion rates were the same in both treatment groups. The results suggest that neuroleptics as well as lithium impair urine concentrating ability.

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

Renal function was examined in 153 manic-depressive patients treated with lithium for more than 5 years, mean 10 years. No significant change was detectable in plasma creatinine. Glomerular filtration rate (GFR) decreased slightly, but significantly, and not until after 17 years of treatment did the regression line reach the lower confidence limit in the reference material. GFR was generally only moderately decreased. Renal concentrating capacity was significantly reduced during the whole investigation period and did not change with time. GFR was independent of the dosage pattern. The diuresis did not differ markedly in patients given one or three daily doses. In a two-dose group predominantly treated with slow-release tablets, the diuresis was somewhat higher in 75% of the patients but much higher for the rest of the group. Since the prophylactic effect of lithium was the same in the one-dose group (mean dosage 21 mmol/day) as in the two-dose and three-dose groups (mean dosage 27-28 mmol/day), our data indicate that generally employed lithium doses may be reduced somewhat without loss of prophylactic efficacy.

Lithium-induced uremia in rats - a new model of chronic renal failure

Three groups of new-born rats were studied: Group Li/Li treated with Li for 16 weeks, group Li/C treated for 8 weeks followed by 8 weeks without Li, and Group C/C 16 weeks old controls. Both Li-treated groups showed severe reduction of renal function, particularly group Li/Li, where the mean GFR was reduced by 80%. Plasma urea, creatinine, and osmolality were increased, blood hemoglobin and hematocrit were reduced, whereas plasma Na, K, and standard bicarbonate were unchanged. Na clearance was maintained and fractional Na excretion thus increased. Fractional Li excretion was also increased, indicating inhibition of proximal tubular salt and water reabsorption. Renal concentrating ability was markedly reduced. When Li was withdrawn, plasma urea levels remained unchanged or continued to rise, and the concentrating defect persisted. The results demonstrate that Li administration to new-born rats causes irreversible chronic renal failure which may progress even in the absence of Li. This model of chronic renal failure has several characteristics in common with chronic renal failure in humans.

Kidney function in lithium-treated patients. A literature survey

Twenty-three studies of the effect of lithium treatment on tubular and glomerular function are reviewed. They include about 1,450 patients from a total population of more than 2,000. One hundred and thirty-two patients were kidney biopsied. In addition, two specific questions are reviewed: 1) Does combined treatment lithium/neuroleptics affect the kidneys adversely? 2) Do different lithium preparations or treatment schedules affect the kidneys differently?

CONCLUSIONS

In a small proportion of patients long-term lithium treatment causes morphological changes of a tubulointerstitial type and partly irreversible reduction of tubular function. Glomerular function is reduced secondary to tubular atrophy. Combined treatment with neuroleptics does not increase the risk of kidney damage. Types of lithium preparation do not affect kidneys differently. Multiple-dose schedules may be associated with a higher urinary output than one-dose schedule. Reduced renal function may in the future become a problem in an increasing number of patients.

The effect of lithium on renal haemodynamic function

Renal concentrating capacity following 18 hours of fluid deprivation was measured in 75 patients receiving prophylactic lithium therapy, and in 30 affectively ill subjects receiving other drugs. The lithium-treated patients had significantly lower urine osmolality and higher serum osmolality than the control subjects. Older subjects, patients maintained at higher serum lithium levels and those with a history of previous neurotoxicity showed the most impairment. Ten patients with urine osmolalities of less than 700 mOsm/1 following this test were investigated further. Inulin and para-amino hippurate (PAH) clearance rates were determined and the effect of a subpressor challenge of dopamine on these measures was observed. Half of the patients showed some reduction in inulin and PAH clearance, which was greatest in those patients who had been taking lithium for over 10 years. However, all of the patients tested showed the expected increase in renal blood flow and sodium and water excretion in response to dopamine. Six additional patients had clearance estimations made before starting lithium treatment which were repeated after a period of 3-6 months on the drug. No consistent changes in haemodynamics were observed. Lithium clearly reduces renal concentrating capacity, but other measures of renal tubular function were well preserved in patients receiving long-term therapy. Glomerular function may be slightly reduced in patients taking lithium for long periods. The results show that prophylactic lithium treatment does not affect renal cortical function adversely in the majority of patients, but impaired renal concentrating ability is a common accompaniment.

Urinary beta-hexosaminidase excretion in patients treated with lithium, thymoleptic and/or neuroleptic drugs

In order to evaluate the nephrotoxic effect of serum lithium within the therapeutical range, the urinary excretion of beta-hexosaminidase was studied in 44 well-managed long-term lithium treated patients and in 27 healthy controls. In addition, six patients on thylmoleptic and 16 patients on neuroleptic drugs were studied. The enzyme excretion was slightly increased in the lithium treated patients, but not in the patients only treated with thymoleptic or neuroleptic drugs. The findings are consistent with the suggestion that long-term lithium treatment causes a slowly progressive nephropathy. To follow the urinary beta-hexosaminidase excretion might be a measure to identify patients at higher risk. In two cases of lithium intoxication the enzyme excretion was considerably increased.

Severe functional and structural changes caused by lithium in the developing rat kidney

Lithium (Li) was administered to rats during maternal pregnancy and/or 8 weeks post-natally, to study the effects on renal function and structure in the developing kidney. Plasma Li was 0.5-1.0 mmol/l 3 and 8 weeks post-natally. Functionally, post-natal Li leads to growth retardation, polyuria with lowering of renal concentration ability, and uremia associated with as much as 80% lowering of the normal glomerular filtration rate (GFR). Pre-natal Li alone did not affect the concentrating ability but caused a 20% increase in GFR when evaluated 8 weeks post-natally. Post-natal Li caused very severe structural changes, consisting of up to 3 mm cortical cysts (= dilated distal convoluted tubules), extensive interstitial fibrosis with cell infiltration, and atrophy of the cortical collecting ducts. Morphometric measurements showed a significant reduction in the volume of the proximal tubular cells. Pre-natal Li caused only slight structural changes, and animals treated both pre- and post-natally were less affected than animals treated post-natally only. The structural changes caused by post-natal Li were unrelated to changes in the concentrating ability but showed a significant correlation with the lowering of the GFR. It is concluded that the post-natally developing rat kidney is particularly sensitive to the nephrotoxic effects of Li, which in low concentrations causes impairment of renal function, leading to uremia. Pre-natal Li exposure by maternal lithium treatment had little effect on renal function and structure when evaluated post-natally.

Renal function and biopsy findings in patients on long-term lithium treatment

Nine patients on long-term lithium treatment (3 to 13 years) had abnormal renal function with a decreased GFR and/or a decreased maximal urinary concentration capacity. Four patients had received lithium as the only drug, whereas five patients had had concomitant treatment with neuroleptics. No patient had a history of nephrourological diseases. Abnormal renal morphology was present in the biopsy samples from all patients. Cortical fibrosis was found in a variable degree. Dilated tubules and microcysts in which the epithelial lining was clearly abnormal were found in majority of samples. Electron micrographically, two types of abnormal epithelial cells were observed, one with small elongated mitochondria with dense matrix and the other with large spherical and less dense mitochondria. In distal tubules, mitochondrial swelling, accumulation of cytosegrosomes, and nuclear pyknosis dominated the picture. These findings indicate a tubulointerstitial nephropathy and support the hypothesis that long-term lithium treatment may cause renal damage in susceptible patients.

Effects of lithium and neuroleptics and combinations of the two on renal function and structure in rats

The effects of 8 weeks of treatment with lithium and neuroleptics, alone and combined, on renal concentrating ability and morphology were studied in rats. LiCl was administered in the diet and neuroleptics were given as one daily dose: haloperidol 1 mg/kg, chlorpromazine 15 mg/kg, and perphenazine 4 mg/kg. Plasma lithium levels were about 1 mmol/l, and the area under the plasma concentration curve was not statistically different in the control and neuroleptic groups. Rats treated with lithium developed marked polyuria which was less in rats receiving neuroleptics concomitantly. After 8 weeks, rats treated with lithium alone showed marked impairment of renal concentrating ability and moderate degree of structural renal changes. Neuroleptics alone had no effect on concentrating ability or renal morphology, nor did they aggravate the changes caused by lithium. In fact, neuroleptics seemed to improve the concentrating ability in rats treated with lithium. It is concluded that in rats high doses of neuroleptics do not potentiate lithium-induced functional and structural renal changes.

Lithium treatment and kidney function. A follow-up study of 237 patients in long-term treatment

Two years after a survey of the kidney function in 237 patients given long-term lithium treatment the patients were invited for reexamination. Of 184 patients who came for the reexamination 147 had continued lithium treatment; in 37 patients the treatment had been discontinued. The lithium-treated patients were compared with a group of 68 manic-depressive patients who were about to be given prophylactic lithium treatment but who had not yet started. Neither the patients who continued nor the patients who had discontinued lithium showed any deterioration of glomerular filtration rate as assessed through determination of the 24-h creatinine clearance and the serum creatinine concentration; mean values in the lithium-treated patients were the same as mean values in patients not yet given lithium. Impairment of renal water reabsorption, revealed by increased 24-h urine volume and decreased urine osmolality after DDAVP, had progressed in the patients who continued lithium treatment, and multiple regression analysis revealed the duration of treatment and the serum lithium level to be significant predictor variables. In the patients who had discontinued lithium the changes in renal water handling had decreased. The urine volume was the same as that found in the patients not yet given lithium; maximum urine osmolality had not become fully normalized. Side effects such as thirst, nycturia, tremor, diarrhoea, oedema, and weight gain were found with the same frequency at the second as at the first examination in the patients who had continued lithium. In the patients who had discontinued lithium they were infrequent or absent.