Reducing salt intake by urine chloride self-measurement in non-compliant patients with chronic kidney disease followed in nephrology clinics: a randomized trial

Cardiovascular complications in chronic kidney disease: a review from the European Renal and Cardiovascular Medicine Working Group of the European Renal Association

Chronic kidney disease (CKD) is classified into five stages with kidney failure being the most severe stage (stage G5). CKD conveys a high risk for coronary artery disease, heart failure, arrhythmias, and sudden cardiac death. Cardiovascular complications are the most common causes of death in patients with kidney failure (stage G5) who are maintained on regular dialysis treatment. Because of the high death rate attributable to cardiovascular (CV) disease, most patients with progressive CKD die before reaching kidney failure. Classical risk factors implicated in CV disease are involved in the early stages of CKD. In intermediate and late stages, non-traditional risk factors, including iso-osmotic and non-osmotic sodium retention, volume expansion, anaemia, inflammation, malnutrition, sympathetic overactivity, mineral bone disorders, accumulation of a class of endogenous compounds called 'uremic toxins', and a variety of hormonal disorders are the main factors that accelerate the progression of CV disease in these patients. Arterial disease in CKD patients is characterized by an almost unique propensity to calcification and vascular stiffness. Left ventricular hypertrophy, a major risk factor for heart failure, occurs early in CKD and reaches a prevalence of 70-80% in patients with kidney failure. Recent clinical trials have shown the potential benefits of hypoxia-inducible factor prolyl hydroxylase inhibitors, especially as an oral agent in CKD patients. Likewise, the value of proactively administered intravenous iron for safely treating anaemia in dialysis patients has been shown. Sodium/glucose cotransporter-2 inhibitors are now fully emerged as a class of drugs that substantially reduces the risk for CV complications in patients who are already being treated with adequate doses of inhibitors of the renin-angiotensin system. Concerted efforts are being made by major scientific societies to advance basic and clinical research on CV disease in patients with CKD, a research area that remains insufficiently explored.

The World Hypertension League Science of Salt: a regularly updated systematic review of salt and health outcomes studies (Sept 2019 to Dec 2020)

The World Hypertension League Science of Salt health outcomes review series highlights high-quality publications relating to salt intake and health outcomes. This review uses a standardised method, outlined in previous reviews and based on methods developed by WHO, to identify and critically appraise published articles on dietary salt intake and health outcomes. We identified 41 articles published between September 2019 to December 2020. Amongst these, two studies met the pre-specified methodological quality criteria for critical appraisal. They were prospective cohort studies and examined physical performance and composite renal outcomes as health outcomes. Both found an association between increased/higher sodium intake and poorer health outcomes. Few studies meet criteria for high-quality methods. This review adds further evidence that dietary salt reduction has health benefits and strengthens evidence relating to health outcomes other than blood pressure and cardiovascular disease. We observe that most studies on dietary sodium do not have adequate methodology to reliably assess sodium intake and its association with health outcomes.

Thiazide diuretics are back in CKD: the case of chlorthalidone

Sodium and volume excess is the fundamental risk factor underlying hypertension in chronic kidney disease (CKD) patients, who represent the prototypical population characterized by salt-sensitive hypertension. Low salt diets and diuretics constitute the centrepiece for blood pressure control in CKD. In patients with CKD stage 4, loop diuretics are generally preferred to thiazides. Furthermore, thiazide diuretics have long been held as being of limited efficacy in this population. In this review, by systematically appraising published randomized trials of thiazides in CKD, we show that this class of drugs may be useful even among people with advanced CKD. Thiazides cause a negative sodium balance and reduce body fluids by 1-2 l within the first 2-4 weeks and these effects go along with improvement in hypertension control. The recent CLICK trial has documented the antihypertensive efficacy of chlorthalidone, a long-acting thiazide-like diuretic, in stage 4 CKD patients with poorly controlled hypertension. Overall, chlorthalidone use could be considered in patients with treatment-resistant hypertension when spironolactone cannot be administered or must be withdrawn due to side effects. Hyponatremia, hypokalaemia, volume depletion and acute kidney injury are side effects that demand a vigilant attitude by physicians prescribing these drugs. Well-powered randomized trials assessing hard outcomes are still necessary to more confidently recommend the use of these drugs in advanced CKD.

Development of semi-quantitative urinary sodium test strip

Excessive salt consumption has been associated with greater risk of hypertension. Therefore, monitoring of dietary sodium consumption should be prioritized. As sodium is mainly excreted through urine, 24-hours urine sample can be used to estimate individual sodium intake. Thus, a simple and inexpensive semi-quantitative urinary sodium detection test strip was developed based on the enzymatic reaction between β-galactosidase and chlorophenol red-β-D-galactopyranoside. When tested, colour formation was distinguished at 0 M (chartreuse yellow), 0.05 M (sunflower), 0.1-0.15 M (mango tango), and 0.2-0.25 M (persimmon) sodium. Analysis from ImageJ showed a linear result (r² >0.9), low SD, and significant increase in magenta difference (p<0.01) between 0 M and 0.05-0.25 M sodium. Test strip can detect 0.03 M sodium at minimum but did not last for >2 days in adverse storage conditions (laboratory conditions, ∼80% relative humidity, 40°C, and direct light exposure) when stored in test strip bottles, and even shorter when exposed to the environment. The presence of urinary potassium, urea, and glucose did not affect test strip performance. Test strip produced comparable results to flame photometry with <15% variation when tested on overnight, random spot, and 24-hours urine samples. Overall, the developed test strip can be used to enzymatically semi-quantify 0.05-0.25 M sodium. Test strip was developed by using β-galactosidase and chlorophenol red-β-D-galactopyranoside for the enzymatic detection of urinary sodium. Test strip could perform urinary sodium monitoring by providing colour indicator based on the concentration of sodium tested in the urine sample at a quicker timing in comparison to current quantification methods. The developed test strip could be used by hypertensive and normotensive users conveniently and repeatably wherever and whenever possible without additional equipment. This article is protected by copyright. All rights reserved.