The urine-to-plasma urea concentration ratio is associated with eGFR and eGFR decline over time in a population cohort.

Background: Evaluation of renal function and of factors associated with its decline are important public health issues. Besides markers of glomerular function [e.g.

Association of the Urine-to-Plasma Urea Ratio With CKD Progression.

Rationale & Objectives: The urine-to-plasma (U/P) ratio of urea is correlated with urine-concentrating capacity and associated with progression of autosomal dominant polycystic kidney disease. As a proposed biomarker of tubular function, we hypothesized that the U/P urea ratio would also be associated with progression of more common forms of chronic kidney disease (CKD).

Study Design: Observational cohort study.

Vaptans or voluntary increased hydration to protect the kidney: how do they compare?

The adverse effects of vasopressin (AVP) in diverse forms of chronic kidney disease have been well described. They depend on the antidiuretic action of AVP mediated by V2 receptors (V2R). Tolvaptan, a selective V2R antagonist, is now largely used for the treatment of patients with autosomal dominant polycystic kidney disease.

Water intake and progression of chronic kidney disease: the CKD-REIN cohort study.

Background: Optimal daily water intake to prevent chronic kidney disease (CKD) progression is unknown. Taking the kidney's urine-concentrating ability into account, we studied the relation of kidney outcomes in patients with CKD to total and plain water intake and urine volume.

Methods: Including 1265 CKD patients [median age 69 years; mean estimated glomerular filtration rate (eGFR) 32 mL/min/1.

Low hydration status may be associated with insulin resistance and fat distribution: analysis of the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2010.

We aimed to identify the association of hydration status with insulin resistance (IR) and body fat distribution. A total of 14 344 adults participated in the Korea National Health and Nutrition Examination Survey 2008-2010. We used urine specific gravity (USG) to indicate hydration status, and HOMA-IR (homoeostasis model assessment of IR) and trunk:leg fat ratio (TLR) as primary outcomes.

Medullary and cortical thick ascending limb: similarities and differences.

The thick ascending limb of the loop of Henle (TAL) is the first segment of the distal nephron, extending through the whole outer medulla and cortex, two regions with different composition of the peritubular environment. The TAL plays a critical role in the control of NaCl, water, acid, and divalent cation homeostasis, as illustrated by the consequences of the various monogenic diseases that affect the TAL. It delivers tubular fluid to the distal convoluted tubule and thereby affects the function of the downstream tubular segments.

What can copeptin tell us in patients with autosomal dominant polycystic disease?

Vasopressin is known to contribute to disease progression in autosomal dominant polycystic disease (ADPKD) by its influence on cyclic adenosine monophosphate that directly promotes cyst growth. In addition, vasopressin probably contributes to progression by inducing glomerular hyperfiltration as shown in other forms of chronic kidney diseases. The measurement of plasma copeptin, a marker of vasopressin secretion, could help identify patients at higher risk of fast progression and those expected to benefit the most from vasopressin V2 receptor blockade.

Glucagon revisited: Coordinated actions on the liver and kidney.

Glucagon secretion is stimulated by a low plasma glucose concentration. By activating glycogenolysis and gluconeogenesis in the liver, glucagon contributes to maintain a normal glycemia. Glucagon secretion is also stimulated by the intake of proteins, and glucagon contributes to amino acid metabolism and nitrogen excretion.

Plasma copeptin and chronic kidney disease risk in 3 European cohorts from the general population.

Background: The prevalence of chronic kidney disease (CKD) is increasing worldwide. The identification of factors contributing to its progression is important for designing preventive measures. Previous studies have suggested that chronically high vasopressin is deleterious to renal function.

Renal potassium handling in carriers of the Gly40Ser mutation of the glucagon receptor suggests a role for glucagon in potassium homeostasis.

Plasma potassium concentration (P ) is tightly regulated. Insulin is known to favor potassium entry into cells. But how potassium leaves the cells later on is not often considered.

Improved protocols for the study of urinary electrolyte excretion and blood pressure in rodents: use of gel food and stepwise changes in diet composition.

Many experimental protocols in rodents require the comparison of groups that are fed different diets. Changes in dietary electrolyte and/or fat content can influence food intake, which can potentially introduce bias or confound the results. Unpalatable diets slow growth or cause weight loss, which is exacerbated by housing the animals in individual metabolic cages or by surgery.

Association of a Low-Protein Diet With Slower Progression of CKD.

Introduction: Reducing protein intake is recommended for slowing chronic kidney disease (CKD) progression, but assessment of its true effectiveness is sparse.

Methods: Using the Maroni formula, we assessed dietary protein intake (DPI) from 24-hour urinary urea excretion in 1594 patients (67% men and 33% women) with CKD, 784 of whom also had 7-day food records. Cause-specific hazard ratios (HRs) and 95% confidence intervals for the competing risks of DPI-associated end-stage renal disease (ESRD) or death were estimated in 1412 patients with baseline glomerular filtration rate ≥15 ml/min per 1.

Effects of hydration on plasma copeptin, glycemia and gluco-regulatory hormones: a water intervention in humans.

Purpose: High plasma copeptin, a marker of vasopressin, predicts diabetes mellitus. We tested if copeptin could be suppressed by increased water intake in healthy individuals, and if a water-induced change in copeptin was accompanied by altered concentrations of glucose, insulin or glucagon.

Methods: Thirty-nine healthy individuals underwent, in random order, 1 week of high water intake (3 L/day on top of habitual intake) and 1 week of normal (habitual) fluid intake (control).

Relationship between Sodium Intake and Water Intake: The False and the True.

Generally, eating salty food items increases thirst. Thirst is also stimulated by the experimental infusion of hypertonic saline. But, in steady state, does the kidney need a higher amount of water to excrete sodium on a high than on a low sodium intake? This issue is still controversial.

Validation of Surrogates of Urine Osmolality in Population Studies.

Background: The importance of vasopressin and/or urine concentration in various kidney, cardiovascular, and metabolic diseases has been emphasized recently. Due to technical constraints, urine osmolality (Uosm), a direct reflect of urinary concentrating activity, is rarely measured in epidemiologic studies.

Methods: We analyzed 2 possible surrogates of Uosm in 4 large population-based cohorts (total n = 4,247) and in patients with chronic kidney disease (CKD, n = 146).

Antagonism of vasopressin V2 receptor improves albuminuria at the early stage of diabetic nephropathy in a mouse model of type 2 diabetes.

Aims: Vasopressin is increased in diabetes and was shown to contribute to development of diabetic nephropathy through V2 receptor (V2R) activation in an experimental model of type 1 diabetes. The role of V2R in type 2 diabetes remains undocumented. This study addresses the issue in a mouse model of type 2 diabetes.

Vasopressin and diabetic nephropathy.

Purpose Of Review: The prevalence of diabetic kidney disease (DKD) is increasing worldwide. Despite major therapeutic advances in the last decades in DKD, the current standard of care let many people progress to severe stages. Vasopressin secretion is increased in diabetes, and its potential role in the onset and progression of DKD is being re-investigated.

Urinary Sodium Concentration Is an Independent Predictor of All-Cause and Cardiovascular Mortality in a Type 2 Diabetes Cohort Population.

Objective: Sodium intake is associated with cardiovascular outcomes. However, no study has specifically reported an association between cardiovascular mortality and urinary sodium concentration (U). We examined the association of U with mortality in a cohort of type 2 diabetes (T2D) patients.

Acute and chronic hyperglycemic effects of vasopressin in normal rats: involvement of V receptors.

Recent epidemiological studies have revealed novel relationships between low water intake or high vasopressin (AVP) and the risk of hyperglycemia and diabetes. AVP V and V receptors (R) are expressed in the liver and pancreatic islets, respectively. The present study was designed to determine the impact of different levels of circulating AVP on glucose homeostasis in normal Sprague-Dawley rats, as well as the respective roles of VR and VR.

Plasma Copeptin, Kidney Outcomes, Ischemic Heart Disease, and All-Cause Mortality in People With Long-standing Type 1 Diabetes.

Objective: Plasma copeptin, a surrogate for vasopressin, has been associated with a decline in renal function and albuminuria in population-based studies as well as with progression of diabetic nephropathy in people with type 2 diabetes. We assessed the risk of kidney and coronary events and all-cause mortality associated with plasma copeptin in people with type 1 diabetes.

Research Design And Methods: Plasma copeptin was measured in baseline samples of the GENEDIAB (n = 398; 56% male; mean ± SD age 45 ± 12 years and diabetes duration 28 ± 10 years) and GENESIS (n = 588; 52% male; age 42 ± 11 years; diabetes duration 27 ± 9 years) cohorts.

Metabolic and Kidney Diseases in the Setting of Climate Change, Water Shortage, and Survival Factors.

Climate change (global warming) is leading to an increase in heat extremes and coupled with increasing water shortage, provides a perfect storm for a new era of environmental crises and potentially, new diseases. We use a comparative physiologic approach to show that one of the primary mechanisms by which animals protect themselves against water shortage is to increase fat mass as a means for providing metabolic water. Strong evidence suggests that certain hormones (vasopressin), foods (fructose), and metabolic products (uric acid) function as survival signals to help reduce water loss and store fat (which also provides a source of metabolic water).

Glucagon actions on the kidney revisited: possible role in potassium homeostasis.

It is now recognized that the metabolic disorders observed in diabetes are not, or not only due to the lack of insulin or insulin resistance, but also to elevated glucagon secretion. Accordingly, selective glucagon receptor antagonists are now proposed as a novel strategy for the treatment of diabetes. However, besides its metabolic actions, glucagon also influences kidney function.