[About the purple urine bag syndrome]

Urine staining is described as a clinical sign due to the presence of some diseases. The purple colour is rare and can be worrisome. It has only been described in a syndrome called Purple Urine Bag Syndrome (PUBS). This coloration is the result of a urinary tract infection in patients with an indwelling catheter for a long time. An overview of the mechanisms causing this syndrome and of its management and prognosis will be discussed in this short communication.

[Autosomal dominant polycystic kidney disease : a pediatric perspective]

Polycystic kidney disease (PKD) is the most prevalent inherited kidney disease. The disease is usually asymptomatic until adulthood. End-stage renal disease occurs generally after the age of 55 years, with a large inter-individual variability. Renal cyst formation begins early in life, and animal models have shown that treatments able to prevent the cyst growth slow down the renal function decline. A treatment by tolvaptan is currently used in adults to decelerate PKD progression. Until now there is no consensus about the appropriate time to screen for PKD in children. However, these scientific progresses raise the interest of determining early (i.e. pediatric) predictive markers of renal function decline.

[COVID-19 inside dialysis units]

COVID-19 has been the center of global attention and concern for the last months. Patients undergoing dialysis and especially those treated at the hospital are likely to be infected, due to their mandatory presence at the hospital several times a week and due to their intrinsic fragility in regard of chronic kidney disease, often an older age, and the presence of many associated comorbidities. Thereby, patients with chonic kidney disease treated by haemodialysis have higher odds of a more severe COVID-19 infection with a high mortality rate. Prevention is thus a high priority for these patients.

[Kidney injury in COVID-19]

The SARS-CoV-2 virus causes a respiratory distress syndrome, the main symptom of COVID-19 (for "COronaVIrus Disease 2019"). This infectious disease has been causing a major health and socio-economic pandemic since December 2019. The pulmonary alveolus is regarded as the main target of SARS-CoV-2. However, this coronavirus is capable of directly or indirectly affecting other organs, including the kidneys. Here, we summarize the presumed pathophysiology of COVID-19 renal disease. The incidence of acute kidney injury ranges from 0,5 to 22 % of all patients infected with SARS-CoV-2. The need for renal replacement therapy is reported in 5-9 % of patients in intensive care. Histological analysis of renal biopsies mainly shows acute tubular necrosis of varying severity, as well as the congestion of glomerular and peri-tubular capillaries. Endothelitis has been described in few cases. Evidence for a factual inflammation of the glomerulus remains controversial. The medium/long term consequences of COVID-19 nephropathy are unknown and will deserve a tight follow-up.

[Arguments for a role of the gut microbiota in the pathophysiology of hypertension]

The gut microbiota refers to the community of microorganisms living in the mammalian digestive tract. Over the past decades, numerous preclinical and clinical studies have suggested that gut microbiota is involved in the physiological homeostasis of the host, particularly in the immune and metabolic systems. Furthermore, the dysfunction of gut microbiota, also called "dysbiosis", has been associated with various diseases, such as the metabolic syndrome or chronic kidney disease. In this review, we summarize the knowledge about the possible role of gut microbiota in the development of arterial hypertension. We detail the pathophysiological mechanisms, namely involving short-chain fatty acids produced by the bacterial fermentation of food carbohydrates. These metabolites are reabsorbed by the intestinal mucosa and interact with a multitude of G-protein coupled receptors at the surface of cells involved in blood pressure regulation, including renal tubular cells. These observations open up innovative diagnostic and therapeutic approaches in arterial hypertension, which is a major public health problem.

[Novelties in arterial hypertension management in the last decade]

Hypertension remains one of the most important cardiovascular risk factors. In spite of many efforts for its management, the control of high blood pressure remains insufficient. In the last decade, no new antihypertensive drug was released. The main effort to improve blood pressure control was put on the validation of the hypertensive status, the stimulation of home blood pressure measurement and the therapeutic education of the patients. The releasing in 2018 of new guidelines, which are clear and more simple, would help more efficiently fight against hypertension, the still present silent killer. In Europe, the usual blood pressure target has been kept, i.e.a lowering of blood pressure below 140/90 mmHg in all fit patients whatever their age. Lower target could be proposed according to the patient tolerance. Treatment is decided according to cardiovascular risk evaluation. Quickly a combination of two antihypertensive agents in a single pill is proposed to improve efficacy of the treatment. We also need the help of the family, nurses and pharmacists to increase the chance of a better blood pressure control, which is necessary to get an optimal cardiovascular protection.

[Therapeutic innovation in nephrology : 10 years of progress]

Chronic kidney disease (CKD) impairs the quality of life and increases the risk for cardiovascular morbimortality. Intensive research is conducted in order to slow down CKD development and progression. During the past decade, a better understanding of the pathophysiological mechanisms of glomerular diseases has highlighted the benefits of rituximab. Progresses have also been made in the understanding of the mechanisms of autosomal polycystic kidney disease, the most frequent inherited kidney disease. These observations led to the discovery and validation of tolvaptan, a blocker of the V2 receptor of the antidiuretic hormone as an innovative treatment. Type 2 diabetic disease is the leading cause worldwide of endstage kidney disease and dialysis. The development of new drugs, such as the gliflozins (inhibiting the sodium glucose reabsorption in the proximal tubule), has contributed to an improvement in the management of the cardiovascular and renal risks especially reducing congestive heart failure rate. Another important progress in nephrology since the beginning of the new century concerns a more precise estimation of the kidney function, which allows to better evaluate the slope of CKD progression and test the influence of different therapeutic approaches aiming at correcting anemia, hyperkalemia, metabolic acidosis and disturbances of calcium and phosphate. The present review summarizes all of these major advances in the field of CKD diagnosis and treatment, and envisions the future of nephrology for the next decade.

[Input of genetic analyses in the differential diagnosis of kidney cysts]

The incidental finding of renal cysts is a common clinical situation given their high prevalence (~ 50 % after the age of 50) and the continuous improvement of abdomen imaging. Diagnosis is central to appropriately dictate the management of the patient. During the diagnostic work-up, it is important to consider (i) the aspect of the cysts, (ii) their number, (iii) and their location, as well as (iv) the age of the patient and his/her personal and familial medical history, (v) the presence of extra-renal manifestations, (vi) and the renal function (including the urinary sediment). Starting from an atypical clinical case characterized by a rapidly evolving chronic kidney disease associated with bilateral renal cysts, we review the classical diagnostic work-up of kidney cysts. As a conclusion, we propose a diagnostic algorithm including both acquired and hereditary nephropathies.

[New 2018 European guidelines for the management of hypertension and comparison with the 2017 American guidelines]

New European guidelines for high blood pressure management have just been published in 2018, modifying those published in 2013 and may be seen as a response to those published by the American societies late 2017. The latter proposed a new definition of hypertension (blood pressure equal or higher than 130/80 mmHg), a therapeutic approach based on the evaluation of the cardiovascular risk, and a blood pressure target inferior to130/80 mmHg in all patients, even those older than 80 years still valid. The European guidelines, on the contrary, maintain the definition threshold of hypertension to a blood pressure equal or higher than 140/90 mmHg. This diagnosis remains based on blood pressure determination at the medical office, confirmed if possible by the use of out of the clinic blood pressure measurements such as home blood pressure and/or 24h ambulatory blood pressure measurement. In comparison with 2013, these new guidelines are closer to the American ones for the management, with the need to evaluate the cardiovascular risk before deciding to initiate a drug treatment in addition to lifestyle and diet measures. A medical therapy will be initiated if the risk is very high for blood pressure in the range of high normal blood pressure (130-139/85-89 mmHg). The blood pressure target should be inferior to 130/80 mmHg in people inferior to 65 years. For those older the blood pressure target should be inferior to 140 mmHg but superior to 120 mmHg. The antihypertensive therapy would be, in the majority of the population, a two-drug combination, if possible in a single pill to enhance the medication compliance that should be frequently checked. If the blood pressure lowering remains resistant to three drugs including a diuretic used at high dose, spironolactone would be recommended, at a low dose. In comparison with 2013, the device-based therapies (renal denervation) are no longer recommended.

[How I explore… a proteinuria]

The measurement of proteinuria is a very simple tool to screen and manage kidney diseases. Its predictive role is also relevant from a cardiovascular point of view. However, the interpretation of the results is not always easy. Indeed, there are several different methods to detect or measure proteinuria (or albuminuria), varying from the measurement on a 24-hour urine collection to the simplest detection with dipsticks or measurement on a random urine sample. Some methods are measuring total proteins, whereas others are measuring more specifically albuminuria. For all methods, pitfalls exist and will be discussed. A positive result must be confirmed by a quantitative measurement on 24-hour collection or on a first morning sample (this last one can only be interpreted as a ratio to urinary creatinine excretion). Lastly, we will briefly discuss the management of a patient with a new diagnosis of proteinuria (or albuminuria).

[Hypertensive crisis]

Hypertensive crisis has fortunately become rarer due to a better diagnosis and management of arterial hypertension. However, its development needs urgent management with adapted therapy according to the severity of the blood pressure levels and the associated clinical signs. After confirmation of severe hypertension (blood pressure above or equal to 180/120 mmHg), target organ lesions have to be looked for and according to their pre-sence, an urgent hospitalization has to be immediately organized. Starting active drug therapy often occurs in intensive units with the intravenous route of administration.

[Bradykinin and cardiovascular protection. Role of perindopril, an inhibitor of angiotensin conversion enzyme]

The endothelium plays a vital role as part of the cardiovascular continuum. Risk factors such as hypertension and dyslipidemia unbalance angiotensin II - bradykinin homeostasis, leading to endothelial dysfunction and changes in vascular structure that promote atherosclerosis and thrombosis. When dealing with risk factors, treatment should focus on the prevention and restoration of endothelial function. Not all cardiovascular drugs are able to reverse vascular and structural endothelial dysfunction. Increasing levels of bradykinin is an effect of the use of angiotensin-converting enzyme inhibitors (ACE-Is), and also a fundamental part of their mode of action. The cardiovascular protection observed with ACE-I, and not with sartans, can be explained rationally by the specific effects of bradykinin on the endothelium. In the pharmacological class of ACE-Is, perindopril likely produces the strongest effects on bradykinin, which may explain, at least in part, the documented superiority of this drug in the prevention and treatment of cardiovascular disease.

[Which place for thiazide and thiazide-like diuretics in patients with type 2 diabetes ?]

The use of thiazides as antihypertensive agents has been challenged because associated metabolic adverse events, including new-onset diabetes. However, these metabolic disturbances are less marked with low-dose of hydrochlorothiazide and with thiazide-like diuretics such as chlorthalidone and indapamide. In post hoc analyses of subgroups of patients with hypertension and type 2 diabetes, thiazide(-like) diuretics resulted in a significant reduction in cardiovascular events, all-cause mortality and hospitalization for heart failure compared to placebo. Furthermore, they were shown to be non-inferior to other antihypertensive agents, including blockers of the renin-angiotensin system in diabetic patients without albuminuria. Benefits attributed to thiazide(-like) diuretics (especially at low dose) in terms of cardiovascular protection outweigh the risk of worsening glucose control and inducing other metabolic disorders in patients with type 2 diabetes. Thus low dose thiazide(-like) drugs still play a major role in the treatment of hypertension in patients with type 2 diabetes.

Performance of glomerular filtration rate estimation equations in Congolese healthy adults: The inopportunity of the ethnic correction

Context and objective

In the estimation of glomerular filtration rate (GFR), ethnicity is an important determinant. However, all existing equations have been built solely from Caucasian and Afro-American populations and they are potentially inaccurate for estimating GFR in African populations. We therefore evaluated the performance of different estimated GFR (eGFR) equations in predicting measured GFR (mGFR).

Methods

In a cross-sectional study, 93 healthy adults were randomly selected in the general population of Kinshasa, Democratic Republic of the Congo, between June 2015 and April 2016. We compared mGFR by plasma clearance of iohexol with eGFR obtained with the Modified Diet in Renal Disease (MDRD) equation with and without ethnic factor, the Chronic Kidney Disease Epidemiology (CKD-EPI) serum creatinine (SCr)-based equation, with and without ethnic factor, the cystatin C-based CKD-EPI equation (CKD-EPI SCys) and with the combined equation (CKD-EPI SCrCys) with and without ethnic factor. The performance of the equations was studied by calculating bias, precision and accuracy within 30% (P30) of mGFR.

Results

There were 48 women and 45 men. Their mean age was 45.0±15.7 years and the average body surface area was 1.68±0.16m². Mean mGFR was 92.0±17.2 mL/min/1.73m² (range of 57 to 141 mL/min/1.73m²). Mean eGFRs with the different equations were 105.5±30.1 and 87.2±24.8 mL/min/1.73m² for MDRD with and without ethnic factor, respectively; 108.8±24.1 and 94.3x20.9 mL/min/1.73m² for CKD-EPI SCr with and without ethnic factor, respectively, 93.5±18.6 mL/min/1.73m² for CKD-EPI SCys; 93.5±18.0 and 101±19.6 mL/min/ 1.73m² for CKD-EPI SCrCys with and without ethnic factor, respectively. All equations slightly overestimated mGFR except MDRD without ethnic factor which underestimated by -3.8±23.0 mL/min /1.73m². Both CKD-EPI SCr and MDRD with ethnic factors highly overestimated mGFR with a bias of 17.9±19.2 and 14.5±27.1 mL/min/1.73m², respectively. There was a trend for better P30 for MDRD and CKD-EPI SCr without than with the ethnic factor [86.0% versus 79.6% for MDRD (p = 0.21) and 81.7% versus 73.1% for the CKD-EPI SCr equations (p = 0.057)]. CKD-EPI SCrCys and CKD-EPI SCys were more effective than creatinine-based equations.

Conclusion

In the Congolese healthy population, MDRD and CKD-EPI equations without ethnic factors had better performance than the same equations with ethnic factor. The equations using Cys C (alone or combined with SCr) performed better than the creatinine-based equations.

[HYPERURICEMIA AND POTENTIAL RISK OF CARDIOVASCULAR AND RENAL DISEASES]

Besides the well accepted need to treat hyperuricemia associated with gout, some large observational studies and small prospective therapeutic trials have suggested that treating asymptomatic hyperuricemia, especially by xanthine oxidase inhibition, the enzyme producing uric acid, could be beneficial for cardiovascular and renal risk prevention. This article discusses the literature about this promising approach, which, however, requests prospective validation.

[Management of hypophosphatemia: a case report]

Hypophosphatemia is defined by a serum phosphate level lower than 0.8 mmol/l. If hypophosphatemia is chronically maintained, it is associated with muscular, osteous, neurological or cardio-respiratory disorders. We describe a patient with isolated hypophosphatemia, detail the mechanisms of phosphate homeostasis, and envisage the differential diagnosis of hypophosphatemia. Furthermore, we propose a sequential decisional algorithm based on basic biological tests and few complementary investigations. Treatment options are reviewed.

[Depression as a common complication of systemic lupus erythematosus]

Systemic lupus erythematosus (SLE) is an inflammatory disease with multiple and disabling consequences, including the psychological status. The prevalence of major depressive episodes among patients suffering from SLE is significantly higher than in healthy people, or people suffering from other inflammatory diseases. While it is obvious that its chronic disease status with a frequently pejorative ending, as well as the number of treatments it requires, are contributing factors, it is likely that due to its pathogenic mechanisms, SLE causes direct injury to the brain, leading to a depressive symptomatology. Numerous hypotheses are under consideration. We shall review them all, recall a few epidemiologic features, add histology and medical imaging contributions and discuss the importance of setting up a fitting therapy for such patients.

[Fixed dose combination perindopril-indapamide-amlodipine (Triplixam) for the treatment of arterial hypertension]

Triplixam is a fixed dose combination of three well known antihypertensive agents, with complementary activities, to control blood pressure in patients with arterial hypertension: perindopril, an angiotensin converting enzyme inhibitor, indapamide, a diuretic whith thiazide-like effects but also specific properties, and amlodipine, a long-acting calcium antagonist of the dihydropyridine family. The potential synergic action allows better control of blood pressure with once daily administration, while limiting the incidence of adverse events. Various presentations with different dosages are available to facilitate individualized therapy. Warnings and precautions for use of every molecule should of course be respected. Such a fixed dose combination should contribute to limit clinical inertia and to improve therapeutic compliance.

[How to manage chronic kidney disease in the elderly?]

From age 30 onwards, kidney function physiologically decreases although this deterioration cannot yet be called chronic kidney disease. The latter appears in those exposed to cardiovascular risk factors associated with inflammation and oxidative stress. A diffuse atherosclerosis then develops Patients with a decreased glomerular filtration rate, especially below the threshold of 45 ml/min, are characterised by a poor physical heath and by cognitive disorders, leading to frailty. In these conditions, a management strategy to reduce the increased risk of acute kidney injury should be outlined and the need for renal replacement therapy be considered. One must try to maintain the best possible quality of life, promoting in some situations a conservative approach.

[Management of arterial hypertension in the elderly]

High blood pressure is very frequent in the elderly; it represents a real threat for the patient's health and a source of huge costs for the economic system. Systolic hypertension is the most frequent form observed in the old, due to large arteries stiffness. Antihypertensive therapy has proven effective to decrease significantly the cardiovascular morbi-mortality and total mortality in this population. A non pharmacological approach is also very useful, but should not be too restrictive. Blood pressure target in patients older than 65 (and, particularly, in octogenarians) is 150/80 mmHg. Blood pressure should be checked in the upright position before changing the drug dosage. The first line therapy in the old should generally be a calcium channel antagonist or a low dose diuretic.

[New guidelines for hypertension management in 2013]

The 2013 guidelines for arterial hypertension have just been released by the European Societies of Cardiology and Hypertension. As already discussed in earlier versions, the decision to treat must be based on the assessment of the cardiovascular risk. The value of out-of-the office blood pressure measurements to confirm the diagnosis of hypertension is underlined and the authors stress the need for a close follow up of non pharmacological therapeutic measures. A novelty, however, consists in the simplification of the blood pressure target under treatment, which must be < 140/90 mmHg in the vast majority of patients, except for octogenerians whose systolic blood pressure target should be < 150 mmHg. For resistant hypertension, renal denervation and carotid baroreceptor stimulation are proposed as new invasive modes of therapy; their clinical values, however, remain to be confirmed.

[Which blood pressure targets in patients with type 2 diabetes?]

Arterial hypertension is commonly observed in patients with type 2 diabetes and aggravates cardiovascular and renal outcomes. Lowering blood pressure is thus a key objective in this population. However, systolic and diastolic blood pressure levels to be reached remain controversial and targets should probably be adjusted according to patient's individual characteristics ("personalized medicine"). This clinical case summarizes the main arguments for selecting blood pressure targets, as far as benefits/risks ratio is concerned, in type 2 diabetic patients with a metabolic syndrome but without complications, with a nephropathy, or with coronary artery disease.

[Dizziness: hypoglycemia, hypotension or spasmophilia?]

The consultation for dizziness is a common problem in clinical practice. Because of the apparent lack of specificity of the complaints, there is a rather high risk to prescribe a variety of sophisticated exams, which will not be very helpful in absence of a well oriented anamnesis and a pertinent clinical examination. The present paper aims at describing a global medical approach, essentially based upon a detailed anamnesis (semiological, chronological and therapeutical arguments), to which may be added a few simple clinical and technical complementary data. This strategy should allow obtaining quite easily pertinent arguments for a differential diagnosis between reactive hypoglycaemia, (orthostatic) hypotension, and hyperventilation crisis (spasmophilia).

[Clinical vignettes. How to diagnose the cause of edema, a clinical approach]

Oedema is a frequent disorder and the easily detectable consequence of an increase of fluid located in the interstitial tissue. It could be localized or generalized and related either to a primary disturbance of hemodynamics at the capillary level, due to a modification of the Starling's law components with secondary water and saline retention, or to a primary retention of salt and water linked to a kidney abnormality. Generalized forms are pitting oedema, most often painless, white, bilateral and symmetric, distributed at the lower part of the body (localisation according to the gravitation law). They are different in their characteristics from localized oedema or lymphoedema which are tough. We propose a diagnostic approach based on medical history, clinical examination which allows a confident medical diagnosis and so an adapted therapy.