Sex differences in vasopressin V₂ receptor expression and vasopressin-induced antidiuresis

National Surveillance of Central Diabetes Insipidus (CDI) in Denmark: results from 5 years registration of 9309 prescriptions of desmopressin to 1285 CDI patients

CONTEXT

Epidemiological data for central diabetes insipidus (CDI) are sparse.

OBJECTIVE

The purpose of this study was to provide accurate epidemiological data on CDI on a national level.

DESIGN AND SETTING

This was a drug utilization and patient registry study during a 5-year period from 2007 to 2011.

METHODS

We used the Danish National Prescription Registry data linked with the Danish National Patient Registry to study the epidemiology of CDI using waiting time distribution and other pharmacoepidemiological methods.

PATIENTS

A total of 1285 patients with CDI were recorded in the observation period and given 9309 prescriptions for desmopressin in the nasal formulation, orodispersible tablet, or conventional tablet.

RESULTS

The period prevalence rate of CDI in Denmark over the 5-year period investigated was 23 CDI patients per 100 000 inhabitants, with a higher prevalence in children and older adults (>80 years of age). The 1-year period prevalence rate of CDI decreased in Denmark over the 5 years from approximately 10 to 7 CDI patients per 100 000 inhabitants. The yearly incidence rate of new cases of CDI was found to be 3 to 4 patients per 100 000. The incidence of (presumable) congenital CDI was found to be 2 infants per 100 000 infants. Half of the patients with CDI prescribed as oral treatment were provided dosing instructions to only administer the drug before bedtime, and one third of the CDI patients either had no specific instructions or were instructed to use the drug as needed. Hospital admissions due to severe hyponatremia occurred in 0.9% of patients over a 5-year period, predominantly in females with an incidence ratio of women to men of 1.8:1.

CONCLUSION

Half of the cases of CDI are acquired later in life. At least half of the patients with CDI are instructed to prevent nocturnal polyuria, but it is not clear whether their CDI remains uncontrolled during the daytime or, alternatively, whether they use desmopressin only as needed. Female patients with CDI had approximately twice the number of hospital admissions due to severe hyponatremia than male patients with CDI.

The physiological and pathophysiological functions of renal and extrarenal vasopressin V2 receptors

The arginine vasopressin (AVP) type 2 receptor (V2R) is unique among AVP receptor subtypes in signaling through cAMP. Its key function is in the kidneys, facilitating the urine concentrating mechanism through the AVP/V2 type receptor/aquaporin 2 system in the medullary and cortical collecting ducts. Recent clinical and research observations strongly support the existence of an extrarenal V2R. The clinical importance of the extrarenal V2R spans widely from stimulation of coagulation factor in the endothelium to as yet untested potential therapeutic targets. These include V2R-regulated membranous fluid turnover in the inner ear, V2R-regulated mitogensis and apoptosis in certain tumor tissues, and numerous other cell types where the physiological role of V2Rs still requires further research. Here, we review current evidence on the physiological and pathophysiological functions of renal and extrarenal V2Rs. These functions of V2R are important, not only in rare diseases with loss or gain of function of V2R but also in relation to the recent use of nonpeptide V2R antagonists to treat hyponatremia and possibly retard the growth of cysts and development of renal failure in autosomal dominant polycystic kidney disease. The main functions of V2R in principal cells of the collecting duct are water, salt, and urea transport by modifying the trafficking of aquaporin 2, epithelial Na(+) channels, and urea transporters and vasodilation and stimulation of coagulation factor properties, mainly seen with pharmacological doses of 1-desamino-8-D-AVP. The AVPR2 gene is located on the X chromosome, in a region with high probability of escape from inactivation; this may lead to phenotypic sex differences, with females expressing higher levels of transcript than males.

Plasma copeptin levels are inversely associated with intima-media-thickness in men: the population-based KORA F4 study

Background

Elevated plasma preprovasopressin (copeptin) levels are associated with cardiovascular complications as well as with an increased risk for type 2 diabetes (T2D). Here, we studied, whether plasma copeptin is related to carotid intima-media thickness (IMT), a measure of early atherosclerosis, and may thus be one explanation for the high cardiovascular risk in T2D.

Methods

Plasma concentrations of copeptin and IMT of the common carotid artery were determined in 1275 participants of the population-based KORA F4 study. We used linear regression models to investigate associations between copeptin levels and IMT.

Results

In the whole study group, copeptin levels were not significantly associated with IMT after adjustment for age and sex. Copeptin and IMT were significantly inversely associated after multivariable adjustment in the total cohort (β = -0.020 mm, 95% CI: -0.037 mm; -0.003 mm), in men (β = -0.035 mm, 95% CI: -0.061 mm; -0.009 mm) and in study participants with prediabetes (β = -0.041 mm, 95% CI: -0.078 mm; -0.005 mm) comparing quartile 4 vs quartile 1. The negative association of copeptin and IMT in men was present after adjustment for age alone. In women and patients with T2D, copeptin was not significantly associated with IMT.

Conclusions

Plasma copeptin was not associated with an increased IMT in our study cohort. In contrast, copeptin levels were related to a lower IMT in men and subjects with prediabetes, suggesting that elevated copeptin concentrations do not exert proatherogenic effects on carotid arteries.

Acute severe hypothyroidism is not associated with hyponatremia even with increased water intake: a prospective study in thyroid cancer patients

BACKGROUND

Hypothyroidism, commonly induced in preparation for radioiodine treatment of differentiated thyroid cancer, is a text-book cause for hyponatremia. Nausea, stress, and increased fluid intake associated with the treatment are expected to exacerbate hyponatremia.

METHODS

We prospectively studied 212 (80% females) consecutive thyroid cancer patients for the incidence of hypothyroidism-induced hyponatremia and associated risk factors.

RESULTS

Mean(SD) age was 39.7(14.1) year, creatinine 82.0(20.8) μmol/l, TSH 141.6(92.0) mU/l, pre- and post-isolation sodium 139.5(2.3) and 137.8(3.0) mEq/l, respectively, and estimated fluid intake during isolation 9.7(6.2) L. Mild hyponatremia (≥130 mEq/l) was present in 18 patients (8.5%) and moderate hyponatremia (≥120 mEq/l) in 4(1.9%), 3 of the latter had elevated creatinine concentration and 2 were on diuretics. There was no significant correlation between post-isolation sodium concentration and TSH concentration (r = 0.03, p = 0.69) or estimated fluid intake (r = 0.10, p =0.17). There was significant correlation between post-isolation sodium concentration and age (r = -0.24, p < 0.0001) and creatinine concentration (r = -0.22, p = 0.001). Pre-post-isolation drop in sodium concentration was more in females (mean difference 1.21, p = 0.02). Compared to eunatremic patients, hyponatremic patients were more likely to have pre-isolation hyponatremia (9% vs. 0.5%, p = 0.03), elevated creatinine concentration (36% vs. 13%, p = 0.008), and to be on diuretics (23% vs. 1%, p = 0.0001).

CONCLUSIONS

In the setting of acute severe hypothyroidism: 1) clinically-important hyponatremia is uncommon; sodium concentration may not need to be monitored unless patients have impaired renal function or are on diuretics, 2) age and female gender are associated with lower sodium concentration. Uncomplicated acute severe hypothyroidism didn't cause clinically-important hyponatremia/SIADH in this cohort of patients.

Age-associated abnormalities of water homeostasis

Findley first proposed the presence of age-related dysfunction of the hypothalamic-neurohypophyseal-renal axis more than 60 years ago. More sophisticated studies have since corroborated his findings. As a result, it is now clear that multiple abnormalities in water homeostasis occur commonly with aging, and that the elderly are uniquely susceptible to disorders of body volume and osmolality. This article summarizes the distinct points along the hypothalamic-neurohypophyseal-renal axis where these changes have been characterized, as well as the clinical significance of these changes, with special attention to effects on cognition, gait instability, osteoporosis, fractures, and morbidity and mortality.

High incidence of mild hyponatraemia in females using ecstasy at a rave party

BACKGROUND

Globally, millions of subjects regularly use ecstasy, a drug popular due to its empathogenic and entactogenic effects. Dilutional hyponatraemia, mainly caused by direct stimulation of antidiuretic hormone (ADH) secretion by ecstasy, is among the many side effects of the drug (active substance 3, 4-methylenedioxymethamphetamine, MDMA). Severe, symptomatic hyponatraemia related to the use of MDMA has been reported in more than 30 cases. The mortality of this complication is high and mainly females are involved. Dramatic cases that reach the literature probably represent the tip of the iceberg. We decided to study the incidence of hyponatraemia in subjects using MDMA at an indoor rave party.

METHODS

The study was performed at the indoor event 'Awakenings', held in Amsterdam in the fall of 2010. The plasma sodium concentration was measured at the party using a point of care method in 63 subjects using MDMA and 44 controls. The use of MDMA was confirmed by a urine test.

RESULTS

The plasma sodium concentration in subjects using MDMA was significantly lower than in those not using the drug (138 ± 2 mmol/L versus 140 ± 2 mmol/L, respectively, P < 0.001). The overall incidence of hyponatraemia, defined as a plasma sodium concentration <136 mmol/L, was 14.3% in MDMA users (9/63 subjects). Most cases of hyponatraemia occurred in females, in whom the incidence was 26.7% (8 of 30 females), with lowest values of 133 mmol/L. The number of ecstasy pills ingested by the females developing hyponatraemia was not different from that ingested by those who did not develop this complication. Fluid intake in ecstasy users exceeded that of non-users, suggesting a dipsogenic effect of the drug.

CONCLUSIONS

Only 3% of males, but no less than ∼25% of females attending a rave party and using MDMA developed mild hyponatraemia during the event. Especially females are therefore probably also at risk of developing severe symptomatic hyponatraemia. Not using MDMA is obviously the best option to prevent MDMA-induced hyponatraemia. However, accepting the fact that millions use the drug every weekend, strategies should also be developed to prevent hyponatraemia in subjects choosing to take MDMA. This would include matching the electrolyte content of the fluids and food ingested to that of the fluids that are lost during the use of MDMA, mainly by perspiration. Users of MDMA and emergency health care workers should become more aware of the relatively high incidence of MDMA-induced hyponatraemia and of potential strategies to prevent this complication.

Temporal delays and individual variation in antidiuretic response to desmopressin

This study aimed to estimate the relationship between pharmacokinetics and the antidiuretic effect of desmopressin. In the investigator-blind, randomized, parallel group study, 5 dose groups and 1 placebo group, each consisting of 12 healthy, overhydrated, nonsmoking male subjects 18–55 yr of age were infused intravenously over 2 h with placebo or 30, 60, 125, 250, and 500 ng desmopressin in 50 ml of normal saline. Plasma desmopressin and urine osmolality rose by variable amounts during the infusions of 60, 125, 250, and 500 ng desmopressin. Plotting mean urine osmolality against the concurrent mean plasma desmopressin yielded a temporal delay between pharmacokinetic (PK) and -dynamic (PD) responses in all dose groups. Using simulation from the indirect-response model, assuming a constant (4 ng/ml) desmopressin concentration, this delay between PK and PD was estimated at 4 h (10th-90th percentile: 1.8–8.1). Within each group, however, there were large individual variations (2- to 10-fold) in the magnitude and duration of the antidiuretic effect. The antidiuretic effect of intravenous desmopressin in water-loaded healthy adults varies considerably due largely to factors other than individual differences in pharmacokinetics. The antidiuretic effect is time as well as dose dependent and may be self-amplifying. The most likely explanation for these findings is that the time required for a given level of plasma desmopressin to exert its maximum antidiuretic effect varies markedly from person to person due to individual differences in the kinetics of one or more of the intracellular mechanisms that promote the reabsorption of solute-free water by principal cells in renal collecting tubules.

The New England Research Institutes, Inc. (NERI) Nocturia Advisory Conference 2012: focus on outcomes of therapy

A consensus statement published in 2011 summarised current research, clinical approaches, and treatment options for nocturia. Since that time, new research has refined our understanding of nocturia in clinically important ways and new evidence has been presented on the efficacy and outcomes of several treatment methods for this underreported, infrequently recognised, and undertreated problem in adults. This paper provides updated guidance to clinicians in light of recent advances in the field.

Severe water intoxication secondary to the concomitant intake of non-steroidal anti-inflammatory drugs and desmopressin: a case report and review of the literature

Most of the clinical data on the safety profile of desmopressin (DDAVP), which is an effective treatment for both polyuric conditions and bleeding disorders, originate from studies on the tailoring of drug treatment, whereas few reports exist describing severe side effects secondary to drug-drug interaction. We herein describe a case of severe hyponatremia complicated by seizure and coma due to the intake of non-steroidal anti-inflammatory drugs (NSAIDs) in a patient on DDAVP replacement therapy for central diabetes insipidus (DI). A 50-yr-old Caucasian man, with congenital central DI, developed an episode of generalized tonic-clonic seizure, resulting in coma immediately after being admitted to the Emergency Unit for weakness and emesis. Based on his medical history and clinical findings, water intoxication secondary to ketoprofen intake (200 mg/day for the last 3 days) concomitant with DDAVP replacement therapy (Minirin(®) 60 mcg 4 tablets a day) was hypothesized as being the cause of the severe euvolemic hypotonic hyponatremia (natremia 113 mEq/l, plasma osmolality 238 mOsm/Kg). After standard emergency procedures, appropriate gradual restoration of serum sodium levels to the normal range was achieved in 72 hours. Hydratation was maintained according to water excretion and desmopressin therapy was re-introduced. We discuss this case report in the context of the published literature. The present report first highlights the potentially life-threatening side effects associated with over-the-counter NSAIDs during DDAVP replacement therapy for central DI. Risks and benefits of co-treatment should be carefully considered and therapeutic alternatives to NSAIDs should be recommended to patients with central DI in order to improve DDAVP safety.

Gender difference in antidiuretic response to desmopressin

Increased age and female gender are well-known risk factors for the development of desmopressin-induced hyponatremia. However, little focus has been on exploring gender differences in the antidiuretic response to desmopressin. Based on an exploratory analysis from three clinical trials, we report a significant gender difference in the effects of desmopressin on nocturnal urine volume that could not be explained by pharmacokinetic differences. Mean desmopressin concentration profiles were tested for covariates, and age and gender were not statistically significant and only weight was significant for log(C(max)) (P = 0.0183) and borderline significant for log(AUC) (P = 0.0571). The decrease in nocturnal urine volume in nocturia patients treated with desmopressin over 28 days was significantly larger for women at the lower desmopressin melt doses of 10 and 25 μg than for men. The ED(50) for men was modeled to be 43.2 μg and 16.1 μg for women, with the ED(50) men/women estimated to be 2.7 (1.3-8.1 95% CI), corresponding to significantly higher sensitivity to desmopressin in women. An increasing incidence of hyponatremia with increasing dose was found, and at the highest dose level of 100 μg decreases in serum sodium were approximately twofold greater in women over 50 yr of age than in men. A new dose recommendation stratified by gender is suggested in the treatment of nocturia: for men, 50- to 100-μg melt is an efficacious and safe dose, while for women a dose of 25 μg melt is recommended as efficacious with no observed incidences of hyponatremia. Areas for further research are proposed to uncover pathophysiological mechanism(s) behind these gender differences.