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

Blood mRNA expression levels of glucocorticoid receptors and FKBP5 are associated with depressive disorder and altered HPA axis

BACKGROUND

While depression has been associated with alterations in the hypothalamic-pituitary adrenal (HPA) axis function, there is still controversy regarding the nature and extent of the dysfunction, such as in the debate about hypercortisolism vs. hypocortisolism. It may therefore be necessary to understand whether and how HPA axis function in depression is linked to mRNA expression of key genes regulating this system.

METHODS

We studied 163 depressed outpatients, most of whom were chronically ill, and 181 healthy controls. Blood mRNA expression levels of NR3C1 (including GRα, GRβ, and GR-P isoforms), FKBP4, and FKBP5 were measured at baseline. HPA axis feedback sensitivity was measured by the dexamethasone (Dex)/corticotropin-releasing hormone (CRH) test. The association between mRNA expression levels and HPA axis feedback sensitivity was examined.

RESULTS

Compared to controls, patients showed significantly higher expression of GRα and lower expression of FKBP5, and higher post-Dex cortisol levels, even after controlling for age and sex. FKBP5 expression was significantly positively correlated with cortisol levels in patients, while GRα expression was significantly negatively correlated with cortisol levels in controls.

LIMITATIONS

Most patients were taking psychotropic medications. The large number of correlation tests may have caused type I errors.

CONCLUSIONS

The tripartite relationship between depression, mRNA expression of GR and FKBP5, and HPA axis function suggests that the altered gene expression affects HPA axis dysregulation and, as a result, impacts the development and/or illness course of depressive disorder. The combination of increased GRα expression and decreased FKBP5 expression may serve as a biomarker for chronic depression.

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.

Renal side-effects of long-term lithium treatment

The beta 2-Mg (beta 2-microglobulin) and GAG (glycosaminogyclan) excretions in 107 patients with bipolar disorder who had been on lithium treatment for 1-15 years were compared with 29 matched psychiatric control patients. 24-h urine volume, urine beta 2-Mg, GAG values were significantly higher, and maximal urinary osmolality was significantly lower in patients on lithium than in controls. No relationship was found between creatinine clearances and duration of illness, duration of lithium treatment and daily lithium dosages. Duration of lithium treatment was not related to the concentrating capacity. The beta 2-Mg excretion rates were significantly higher in patients with manifest polyuria and with severe concentration defect.

Polydipsia and hyponatremia in psychiatric patients: challenge to creative nursing care

Among patients with psychiatric disorders, especially schizophrenia, a pattern of extreme polydipsia and polyuria sometimes emerges, usually without readily identifiable medical causes. Hyponatremia may develop and progress to water intoxication, with symptoms including restlessness, confusion, seizures, or even death. We review the clinical features and pathophysiology of this syndrome and discuss nursing roles in identifying and managing patients with polydipsia and hyponatremia. While the causes of polydipsia and hyponatremia are unclear, relevant factors seem to include a possible dysfunction in central nervous system (CNS) thirst and osmoregulatory centers, the inappropriate secretion of or sensitivity to antidiuretic hormone (ADH), and psychoactive drugs. Management techniques for affected patients concentrate on careful observation, fluid restriction, and the minimization of possible exacerbating factors such as high neuroleptic dosage and cigarette consumption.

Prospective studies on a lithium cohort. 2. Renal function. Water and electrolyte metabolism

A cohort of manic-depressive patients given prophylactic lithium treatment were examined before treatment started and at intervals during treatment for up to 7 years. The mean lithium dosage was 23.2 mmol/d and the mean serum lithium concentration 0.68 mmol/l. The treatment did not affect glomerulus function. Urine volume rose by 10-20% and renal concentrating ability fell by 7-10% during the treatment. These changes were markedly smaller than those found in patients treated previously with higher lithium doses and serum lithium concentrations. High urine volumes and low renal concentrating abilities were not more frequent during than before lithium treatment. Complaints of increased thirst, frequent urination, and nycturia were presented more often during than before lithium treatment. Serum concentrations, urinary excretions and renal clearances of sodium and potassium were not altered by the treatment.