High salt intake increases copeptin but salt sensitivity is associated with fluid induced reduction of copeptin in women.

This study investigated if copeptin is affected by high salt intake and whether any salt-induced changes in copeptin are related to the degree of salt sensitivity. The study was performed on 20 men and 19 women. In addition to meals containing 50 mmol NaCl daily, capsules containing 100 mmol NaCl and corresponding placebo capsules were administered during 4 weeks each, in random order. Measurements of 24 h blood pressure, body weight, 24 h urinary volume, and fasting plasma copeptin were performed at high and low salt consumption. Copeptin increased after a high compared to low dietary salt consumption in all subjects 3,59 ± 2,28 versus 3,12 ± 1,95 (P = 0,02). Copeptin correlated inversely with urinary volume, at both low (r = -0,42; P = 0,001) and high (r = -0,60; P < 0,001) salt consumption, as well as with the change in body weight (r = -0,53; P < 0,001). Systolic salt sensitivity was inversely correlated with salt-induced changes of copeptin, only in females (r = -0,58; P = 0,017). As suppression of copeptin on high versus low salt intake was associated with systolic salt sensitivity in women, our data suggest that high fluid intake and fluid retention may contribute to salt sensitivity

THE VASOPRESSIN SYSTEM IN DIABETES MELLITUS, OBESITY AND THE METABOLIC SYNDROME

Background: Animal studies suggest that the arginine vasopressin (AVP) system plays a role in glucose and fat metabolism, but data from humans are limited. Method and results: We analysed plasma copeptin (copeptin), a stable C-terminal fragment of the AVP pro-hormone in the large, Swedish, population-based cohort Malmö Diet and Cancer Study Cardiovascular Cohort (MDC-CC, n=6103). Using baseline (1991-1994) and longitudinal (register- and reinvestigation-based) data from MDC-CC (partly re-investigated 15.8 years later (n=2345)) we examined the association of increasing quartiles of copeptin (lowest quartile as reference) with prevalent diabetes (DM) and other components of the metabolic syndrome (MetS) at baseline, and incident DM, measures of obesity and microalbuminuria at follow up, using multivariable logistic regression. After adjusted for clinical and anthropometric risk factors, cystatin C, and C-reactive protein, increasing copeptin quartile (lowest quartile as reference) was associated with prevalent DM (Ptrend=0.04). Furthermore, copeptin quartile was after adjustment for age, sex, insulin and diabetes mellitus associated with prevalent hypertension (Ptrend=0.004), abdominal obesity (Ptrend=0.002), obesity (P=0.01), top quartile of CRP (Ptrend=0.007) and MetS (adjusted for age and sex only) (Ptrend<0.001). During 12.6 years of register-based follow up 174 subjects (4%) developed new-onset diabetes. The odds of developing DM increased across increasing quartile of copeptin, even after additional adjustment for baseline fasting glucose and insulin (adjusted odds ratios 1.0, 1.37, 1.79, and 2.09; Ptrend =0.004). The association with incident DM remained significant in analyses restricted to subjects with fasting whole blood glucose <5.4 mmol/L at baseline (adjusted odds ratios 1.0, 1.80, 1.92, and 3.48; Ptrend=0.001). When incident cases of DM were captured by a re-examination (n=2345) 15.8 years after baseline, increasing copeptin quartiles predicted DM (odds ratios 1.18, 1.32, 1.46; Ptrend=0.04), abdominal obesity (odds ratios 1.55, 1.30, 1.59; Ptrend=0.04), and microalbuminuria (odds ratios 1.05, 1.08, 1.65, Ptrend=0.02) but not MetS (Ptrend=0.19) after adjustment for age, gender and all MetS components at baseline. Genetic polymorphisms in the human AVP receptor 1a gene (AVPR1A) and 1b gene (AVPR1B) were genotyped in MDC-CC. We found that genetic variance in AVPR1A was associated with high glucose and low triglyceride levels, as well as increased prevalence of DM in subjects with a high fat intake, features strongly resembling mice with selective deletion of the same receptor. Finally, we found that genetic variance in AVPR1B was associated with BMI. This finding was replicated in the MDC replication cohort (n=24344). Conclusion: Elevated copeptin independently predicts DM and abdominal obesity but not the cluster of MetS. Our findings suggest a relationship between a dysregulated vasopressin system and cardiometabolic risk, which could have implications for risk assessment and novel preventive treatments

Copeptin relates to a fatty liver and measures of obesity in a South African population with mixed ethnicities

Purpose: Elevated copeptin, a vasopressin marker, is linked to metabolic disease, and obese rats with low-vasopressin concentration had a decreased risk of liver steatosis. We here investigated the association between copeptin and nonalcoholic fatty liver disease (NAFLD) and possible differences in copeptin concentration between ethnicities. Methods: In this cross-sectional study of 361 South Africans (n = 172 African black, 189 = Caucasian) with a mean age of 45 years and 45% men, plasma copeptin was measured and associated with NAFLD according to a validated fatty liver index accounting for measures of BMI, waist, triglycerides, and gamma-glutamyltransferase. Results: There was no significant difference in copeptin concentrations between ethnicities after age and gender adjustment (p = 0.24). Increasing copeptin tertile levels were significantly associated with obesity, overweight, and abdominal obesity, respectively, after multivariate adjustment for age, gender, ethnicity, and high HOMA-IR (p = 0.02 for all). Individuals in the second and third copeptin tertile had an increased odds (95% CI) of NAFLD of 1.77 (1.04–3.02) and 2.97 (1.74–5.06), respectively, compared to the bottom tertile (p < 0.001). The association between increasing copeptin tertile and NAFLD remained significant after adjustment for age, gender, ethnicity, high HOMA-IR, self-reported current alcohol intake, and statin treatment (p = 0.01). Conclusions: Elevated plasma copeptin is independently associated with NAFLD in a population with mixed ethnicities, pointing at the pharmacologically modifiable vasopressin system as a new mechanism behind NAFLD

The vasopressin system in the risk of diabetes and cardiorenal disease, and hydration as a potential lifestyle intervention

Background: Type 2 diabetes, chronic kidney disease (CKD) and its cardiovascular complications are increasing as health problems worldwide. These diseases are interrelated with overlapping occurrence and once diabetes is established, the risk of cardiorenal disease is dramatically elevated. Thus, a search for unifying modifiable risk factors is key for effective prevention. Summary: Elevated fasting plasma concentration of vasopressin, measured with the marker copeptin, predicts new onset type 2 diabetes as well as renal function decline. Furthermore, we recently showed that increased plasma copeptin concentration independently predicts the development of both CKD and other specified kidney diseases. In consequence, high copeptin is an independent risk factor for cardiovascular disease and premature mortality in both diabetes patients and in the general population. Vasopressin is released when plasma osmolality is high, and the easiest way to lower plasma vasopressin and copeptin concentration is to increase water intake. In a human water intervention experiment with 1 week of 3 L/day increased water intake, the one third of the participants with the greatest copeptin reduction (water responders) were those with a phenotype of low water intake (high habitual plasma copeptin and urine osmolality, and low urine volume). The water-responders had a copeptin reduction of 41% after 1 week of increased water intake compared to a control week; in contrast, a 3% reduction occurred in the other two thirds of the study participants. Among water responders, increased water intake also induced a reduction in fasting glucagon concentration. Key Messages: Elevated copeptin, a measure of vasopressin, is a risk marker of metabolic and cardiorenal diseases and may assist in the detection of individuals at higher risk for these diseases. Furthermore, individuals with high copeptin and other signs of low water intake may experience beneficial glucometabolic effects of increased water intake. Future randomized control trials investigating effects of hydration on glucometabolic and renal outcomes should focus on individuals with signs of low water intake including high plasma copeptin concentration

Plasma copeptin as a predictor of kidney disease

Background: Plasma copeptin, a marker of vasopressin, is associated with renal function decline in the general population. Our aim was to study the links between elevated copeptin and future risk of kidney disease.Methods: Copeptin was measured in a sample of the Malmö Preventive Project (MPP) Reinvestigation (n = 5158) and in the Malmö Diet and Cancer Cardiovascular Cohort (MDC-CC) (n = 5162). According to national registers, 89 subjects in MPP and 180 in MDC-CC developed chronic kidney disease (CKD) during follow-up (8.7 and 19.6 years, respectively).Results: After multivariate adjustment (gender, age, body mass index, smoking status, estimated glomerular filtration rate, prevalent diabetes, systolic blood pressure and prevalent antihypertensive treatment), copeptin (beta-coefficient per 1 standard deviation increment of ln copeptin) was independently associated with increased risk of CKD during follow-up in both cohorts (MPP: (HR) 1.46, 95% confidence interval (CI) 1.18-1.80, P < 0.001; MDC-CC: HR 1.25, 95% CI 1.02-1.54, P = 0.03) among subjects free from prevalent kidney disease at baseline. Furthermore, in MPP, elevated copeptin predicted a specified diagnosis of kidney disease other than CKD (HR 1.31, 95% CI 1.08-1.59, P = 0.006) after multivariate adjustment. In a corresponding analysis in MDC-CC, copeptin was associated with a 10% increased risk, which, however, was non-significant (P = 0.25). A meta-analysis of the MPP and MDC-CC data showed significant association between elevated copeptin and a specified diagnosis of kidney disease other than CKD (HR 1.18, 95% CI 1.05-1.34, P = 0.008).Conclusion: An increased level of copeptin independently predicts development of both CKD and other specified kidney diseases, suggesting that copeptin can be used to identify individuals at risk for kidney disease development

Hyponatremia in the Emergency Department: Could Biomarkers Help in Diagnosis and Treatment?

Objective: Hyponatremia is the most common electrolyte imbalance. The initial treatment decision is based on clinical evaluation of patient volume status but an accurate assessment is difficult, particularly differentiating mild hypovolemia from euvolemia. The aim of this study is to examine if biomarkers are valuable in the early determination of volume status and SIADH diagnosis. Methods: Blood samples were collected from an unselected patient population at entry to the Emergency Department. If the plasma sodium level (P-Na) was ≤125 mmol/L, the sample was frozen for further analysis. Mid-regional pro-atrial natriuretic peptide (MR-proANP), proadrenomedullin (MR-proADM), C-terminal prepro-vasopressin (copeptin), pro-endothelin-1 (proET-1) and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were analysed. A comprehensive assessment of volume status and underlying causes was made after discharge blinded for biomarker results. Results: A total of 81 patients were included. A well substa ntiated volemic state (hypo/eu/hypervolemia) was established in 72 patients (mean age 76 years, 65% women, median P-Na 119 mmol/L). A significant association was observed between MR-proANP levels and volemic state (p = 0.0001). Data was specifically analysed with respect to distinguishing hypo- from euvolemia (n = 59) using logistic regression. In a crude analysis, MR-proANP was significantly related to euvolemia (OR: 2.54 per SD of MR-proANP, 95% CI 1.32 - 4.86, p = 0.005) and remained so after the multivariate backward elimination model (OR: 2.45 per SD of MRproANP, 95% CI 1.22 - 4.91, p = 0.012.), whereas the other studied biomarkers were not. Copeptin levels were not associated with a diagnosis of SIADH. Conclusions: MR-proANP may be of value in early determination of volume status in hyponatremic patients

High water intake and low urine osmolality are associated with favorable metabolic profile at a population level : low vasopressin secretion as a possible explanation

Purpose: Elevated plasma concentration of the vasopressin marker copeptin and low water intake are associated with elevated blood glucose and diabetes risk at a population level. Moreover, in individuals with low urine volume and high urine osmolality (u-Osm), water supplementation reduced fasting plasma (fp) copeptin and fp-glucose. In this observational study, we investigated if low total water intake or high u-Osm correlated with high fp-copeptin and components of the metabolic syndrome at the population level. Methods: In the population-based Malmö Offspring Study (MOS, n = 2599), fp-copeptin and u-Osm from morning urine samples were measured, and diet and total water intake (from beverages and food moisture) was assessed by a 4-day web-based record. Results: Increasing water intake by tertile was after adjustment for age and sex associated with low fp-triglycerides (p = 0.002) and high fp-HDL (p = 0.004), whereas there was no association with the other investigated metabolic traits (HbA1c, fp-glucose, BMI or waist circumference). Increasing u-Osm by tertile was, after adjustment for age and sex, associated with high fp-glucose (p = 0.007), and borderline significantly associated with high HbA1c (p = 0.053), but no association was observed with fp-HDL, fp-triglycerides, BMI or waist circumference. Fp-copeptin concentration correlated significantly with water intake (r = − 0.13, p < 0.001) and u-Osm (r = 0.27, p < 0.001). High copeptin was associated with all investigated metabolic traits (p < 0.001 for all). Conclusion: Low concentrations of the vasopressin marker copeptin is linked to high water intake, low u-Osm, and a favorable metabolic profile, suggesting that vasopressin lowering lifestyle interventions, such as increased water intake, may promote metabolic health