SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Diuretic

176

Aggressive diuretic therapy in a patient who is hospitalized for acute decompensated heart failure often leads to progressive renal dysfunction despite persistent congestion. The underlying mechanisms of this so-called acute cardiorenal syndrome are complex and not fully understood.(1),(2) As initial therapy in this setting, ultrafiltration as compared with diuretic therapy may result in a higher rate of sodium and volume removal, with greater weight loss and less frequent rehospitalizations.(3),(4) These findings have suggested that ultrafiltration can provide more effective relief of congestion than pharmacologic therapy can, particularly in the setting of cardiorenal compromise. Ultrafiltration may also reduce diuretic-induced . . .

Concepts: Medicine, Hospital, Heart failure, Diuretic, Acute accent, Acute decompensated heart failure

105

Objective To prospectively examine the relation between the Dietary Approaches to Stop Hypertension (DASH) and Western diets and risk of gout (ie, the clinical endpoint of hyperuricemia) in men.Design Prospective cohort study.Setting The Health Professionals Follow-up Study.Participants 44 444 men with no history of gout at baseline. Using validated food frequency questionnaires, each participant was assigned a DASH dietary pattern score (based on high intake of fruits, vegetables, nuts and legumes, low fat dairy products, and whole grains, and low intake of sodium, sweetened beverages, and red and processed meats) and a Western dietary pattern score (based on high intake of red and processed meats, French fries, refined grains, sweets, and desserts).Main outcome measure Risk of incident gout meeting the preliminary American College of Rheumatology survey criteria for gout, adjusting for potential confounders, including age, body mass index, hypertension, diuretic use, and alcohol intake.Results During 26 years of follow-up, 1731 confirmed cases of incident gout were documented. A higher DASH dietary pattern score was associated with a lower risk for gout (adjusted relative risk for extreme fifths 0.68, 95% confidence interval 0.57 to 0.80, P value for trend <0.001). In contrast, a higher Western dietary pattern score was associated with an increased risk for gout (1.42, 1.16 to 1.74, P=0.005).Conclusion The DASH diet is associated with a lower risk of gout, suggesting that its effect of lowering uric acid levels in individuals with hyperuricemia translates to a lower risk of gout. Conversely, the Western diet is associated with a higher risk of gout. The DASH diet may provide an attractive preventive dietary approach for men at risk of gout.

Concepts: Nutrition, Metabolic syndrome, Gout, Diuretic, Uric acid, Hyperuricemia, Diets, Fast food

39

The WHO ranks hypertension the leading global risk factor for disease, specifically, cardiovascular disease. Blood pressure is higher in westernized populations consuming sodium-rich processed foods compared to isolated societies consuming potassium-rich natural foods. Evidence suggests that lowering dietary Na(+) is particularly beneficial in hypertensives who consume a high Na(+) diet. Nonetheless, numerous population studies demonstrate a relationship between higher dietary K(+), estimated from urinary excretion or dietary recall, and lower blood pressure regardless of sodium intake. Interventional studies with potassium supplementation suggest it provides a direct benefit; K(+) may also be a marker for other beneficial components of a “natural” diet. Recent studies in rodent models indicate mechanisms for the potassium benefit: the distal tubule Na(+)- Cl(-) cotransporter (NCC) controls Na(+) delivery downstream to the collecting duct where Na(+) reabsorbed by epithelial Na(+) channels (ENaC) drives K(+) secretion and excretion through K(+) channels in the same region. High dietary K(+) provokes a decrease in the NCC activity to drive more K(+) secretion (and Na(+) excretion, analogous to the actions of a thiazide diuretic) whether Na(+) intake is high or low; low dietary K(+) provokes an increase in NCC activity and Na(+) retention, also independent of dietary Na(+) Taken together, the findings suggest that public health efforts directed towards increasing consumption of natural potassium rich foods would reduce blood pressure and, thus, cardiovascular and kidney disease.

Concepts: Epidemiology, Blood, Hypertension, Demography, Potassium, Diuretic, Thiazide, Distal convoluted tubule

36

Thiazide diuretics are among the most widely used treatments for hypertension, but thiazide-induced hyponatremia (TIH), a clinically significant adverse effect, is poorly understood. Here, we have studied the phenotypic and genetic characteristics of patients hospitalized with TIH. In a cohort of 109 TIH patients, those with severe TIH displayed an extended phenotype of intravascular volume expansion, increased free water reabsorption, urinary prostaglandin E2 excretion, and reduced excretion of serum chloride, magnesium, zinc, and antidiuretic hormone. GWAS in a separate cohort of 48 TIH patients and 2,922 controls from the 1958 British birth cohort identified an additional 14 regions associated with TIH. We identified a suggestive association with a variant in SLCO2A1, which encodes a prostaglandin transporter in the distal nephron. Resequencing of SLCO2A1 revealed a nonsynonymous variant, rs34550074 (p.A396T), and association with this SNP was replicated in a second cohort of TIH cases. TIH patients with the p.A396T variant demonstrated increased urinary excretion of prostaglandin E2 and metabolites. Moreover, the SLCO2A1 phospho-mimic p.A396E showed loss of transporter function in vitro. These findings indicate that the phenotype of TIH involves a more extensive metabolic derangement than previously recognized. We propose one mechanism underlying TIH development in a subgroup of patients in which SLCO2A1 regulation is altered.

Concepts: Gene, Metabolism, Renal physiology, Phenotype, Vasopressin, Diuretic, Thiazide, Prostaglandin

34

Current goals in the acute treatment of heart failure are focused on pulmonary and systemic decongestion with loop diuretics as the cornerstone of therapy. Despite rapid relief of symptoms in patients with acute decompensated heart failure, after intravenous use of loop diuretics, the use of these agents has been consistently associated with adverse events, including hypokalemia, azotemia, hypotension, and increased mortality. Two recent randomized trials have shown that continuous infusions of loop diuretics did not offer benefit but were associated with adverse events, including hyponatremia, prolonged hospital stay, and increased rate of readmissions. This is probably due to the limitations of congestion evaluation as well as to the deleterious effects linked to drug administration, particularly at higher dosage. The impaired renal function often associated with this treatment is not extensively explored and could deserve more specific studies. Several questions remain to be answered about the best diuretic modality administration, global clinical impact during acute and post-discharge period, and the role of renal function deterioration during treatment. Thus, if loop diuretics are a necessary part of the treatment for acute heart failure, then there must be an approach that allows personalization of therapy for optimal benefit and avoidance of adverse events.

Concepts: Renal failure, Kidney, Nephrology, Heart failure, Diuretic, Hypokalemia, Loop diuretic, Acute decompensated heart failure

28

Although case reports link proton-pump inhibitor (PPI) use and hypomagnesemia, no large-scale studies have been conducted. Here we examined the serum magnesium concentration and the likelihood of hypomagnesemia (<1.6 mg/dl) with a history of PPI or histamine-2 receptor antagonist used to reduce gastric acid, or use of neither among 11,490 consecutive adult admissions to an intensive care unit of a tertiary medical center. Of these, 2632 patients reported PPI use prior to admission, while 657 patients were using a histamine-2 receptor antagonist. PPI use was associated with 0.012 mg/dl lower adjusted serum magnesium concentration compared to users of no acid-suppressive medications, but this effect was restricted to those patients taking diuretics. Among the 3286 patients concurrently on diuretics, PPI use was associated with a significant increase of hypomagnesemia (odds ratio 1.54) and 0.028 mg/dl lower serum magnesium concentration. Among those not using diuretics, PPI use was not associated with serum magnesium levels. Histamine-2 receptor antagonist use was not significantly associated with magnesium concentration without or with diuretic use. The use of PPI was not associated with serum phosphate concentration regardless of diuretic use. Thus, we verify case reports of the association between PPI use and hypomagnesemia in those concurrently taking diuretics. Hence, serum magnesium concentrations should be followed in susceptible individuals on chronic PPI therapy.Kidney International advance online publication, 16 January 2013; doi:10.1038/ki.2012.452.

Concepts: Receptor, Phosphate, Receptor antagonist, Diuretic, Hypomagnesemia

28

BACKGROUND: While several studies have reported a link between the presence of gout and adverse cardiovascular (CV) events in the general population, none has addressed the question of whether the mortality risk of patients with gout is influenced by disease severity. METHODS: We applied survival analysis methodology to prospectively collected data on clinical and radiographic measures of disease severity and mortality in a specialty clinic based cohort of 706 patients with gout (1992-2008). Standardised mortality ratios (SMR) were calculated to assess the magnitude of excess mortality among patients with gout compared with the underlying general population. RESULTS: Mean follow-up was 47 months. Tophaceous deposition was present in 30.5% of patients; >4 joints were involved in 34.6% of cases. Mean annual flare rate was 3.4. Arterial hypertension (41.2%), hyperlipidaemia (42.2%), diabetes mellitus (20.1%), renal function impairment (26.6%) and a previous CV event (25.3%) were recorded. 64 (9.1%) patients died, death being attributed to vascular causes in 38 (59%) patients. SMR for gout patients was 2.37 (95% CI 1.82 to 3.03), 1.57 (1.18 to 2.05) and 4.50 (2.06 to 8.54) overall, and in men and women, respectively. The presence of tophi and the highest baseline serum urate (SU) levels were independently associated with a higher risk of mortality, in addition to age, loop diuretic use and a history of a previous vascular event. In the multivariable survival regression models, with time varying covariates, the presence of tophi remained a significant mortality risk after adjustment for baseline SU levels (1.98; 1.24 to 3.20). CONCLUSIONS: High baseline SU level and the presence of subcutaneous tophi were both associated with an increased risk of mortality in patients with gout, in most cases attributed to a CV cause. This suggests a plausible pathophysiological link between greater total body urate load and CV disease.

Concepts: Renal failure, Hypertension, Diabetes mellitus, Obesity, Metabolic syndrome, Diuretic, Uric acid, Hyperuricemia

28

In the presence of salt, aldosterone causes hypertension and organ damage via the mineralocorticoid receptor (MR) through various mechanisms. MR antagonists are considered to be potassium-sparing diuretics that exert their effect by blocking MR in the kidney, and they are not the first choice for treating hypertension. However, the importance and usefulness of inhibiting aldosterone in the management of hypertension have recently been revealed in both the basic and clinical fields. In Japan, both the selective MR antagonist eplerenone and the non-selective MR antagonist spironolactone are indicated for the treatment of hypertension. Although these drugs are generally used in the same manner, in some cases they require differentiation. This differentiation is divided into two types due to the differences in their features and differences in their contraindications in Japan. Based on a number of studies on MR antagonists that have been recently published, the diseases and clinical conditions targeted by MR antagonists appear to be likely to increase in the future. In Japan, we consider it necessary to carefully differentiate spironolactone from eplerenone in regard to their intended uses.Hypertension Research advance online publication, 22 November 2012; doi:10.1038/hr.2012.182.

Concepts: Hypertension, Aldosterone, Receptor antagonist, Spironolactone, Potassium-sparing diuretic, Diuretic, Aldosterone antagonist, Eplerenone

27

Prevention of recurrent calcium stone disease includes treatment with thiazide and thiazide-type diuretics to reduce urinary calcium (UCa) levels, with the reduction in UCa correlating with risk of stone recurrence. There has been a recent trend of using lower doses of these medications and change from chlorthalidone (CTL) use to hydrochlorothiazide (HCTZ) use. It is unknown whether low doses of HCTZ are effective in lowering UCa levels to target levels. We hypothesize that HCTZ is associated with less reduction in UCa than is CTL when comparing currently used doses. Retrospective observational study of stone-formers was seen in metabolic stone clinic during a 3 years period. Data included patient demographics, co-morbidities, and 24 h urine electrolyte composition. Primary outcome was the change in 24 h UCa. 322 patients were identified with 112 meeting criteria and used in analysis. The majority were placed on HCTZ (n = 42) or CTL (n = 47) 25 mg QD. Patients on CTL 25 mg had a greater reduction in UCa (164 mg; 41 %) than those on HCTZ (85 mg; 21 %), p = 0.01. Neither CTL nor HCTZ at 12.5 mg QD significantly lowered UCa. There was a decrease in serum [K] of 0.5 Meq/L (p = 0.001) in patients on CTL 25 mg daily, but no significant difference in severe hypokalemia or arrhythmia compared to HCTZ. Our data show that CTL is associated with greater reduction in 24 h UCa compared to similarly dosed HCTZ.

Concepts: Kidney, Observational study, Urinary bladder, Urethra, Gout, Diuretic, Hydrochlorothiazide, Hypokalemia

27

: Unfortunately, patients with congestive heart failure suffer frequent admissions for the management of fluid overload. Loop diuretics are pivotal in the management of this common clinical problem. Although loop diuretics have been in clinical use since the 1960s, we still do not understand how to optimally administer these drugs. It is unknown why some decompensated heart failure patients exhibit improvements in renal function with diuresis, whereas others display renal function deterioration, limiting attainment of euvolemia. Here the physiologic interactions between the failing heart and kidneys are reviewed. A conceptual framework is presented that emphasizes the balance between tubuloglomerular feedback and venous congestion in determining renal function during loop diuretic use in heart failure. Within this framework, guidelines are derived that seek to maximize the chance for achieving adequate volume removal while maintaining stable or improved renal function during the treatment of acute decompensated heart failure.

Concepts: Renal failure, Nephrology, Hypertension, Heart failure, Diuretic, Hypokalemia, Loop diuretic, Acute decompensated heart failure