Mortality, hospitalization and transfer to haemodialysis and hybrid therapy, in Japanese peritoneal dialysis patients

Background and objectives: Survival of peritoneal dialysis (PD) patients in Japan is high, but few reports exist on cause-specific mortality, transfer to haemodialysis (HD) or hybrid dialysis and hospitalisation risks. We aimed to identify reasons for transfer to HD, hybrid dialysis and hospitalisation in the Japan Peritoneal Dialysis and Outcomes Practice Patterns Study. Methods: This observational study included 808 adult PD patients across 31 facilities in Japan in 2014–2017. Information on all-cause and cause-specific mortality and hospitalisation and permanent transfer to HD and PD/HD hybrid therapy were prospectively collected and rates calculated. Results: Median follow-up time was 1.66 years where 162 patients transferred to HD, 79 transferred to hybrid dialysis and 74 patients died. All-cause and cardiovascular disease (CVD)-related mortality rates were 5.1 and 1.7 deaths/100 patient-years, respectively. Rates of transfer to HD and hybrid therapy were 11.2 and 5.5 transfers/100 patient-years, respectively. Among HD transfers, 40% were due to infection (including peritonitis), while 20% were due to inadequate solute/water clearance. Eighty-one percent of hybrid dialysis transfers were due to inadequate solute/water clearance. All--cause, peritonitis-related and CVD-related hospitalisation rates were 120.4, 21.1 and 15.6/100 patient-years, respectively. Median hospital length of stay was 19 days. Conclusions: Mortality, hospitalisation and transfer to HD/hybrid dialysis rates are relatively low in Japan compared to many other countries with hybrid transfers, accounting for one-third of dialysis transfers from PD. Further study is needed to explain the high inter-facility variation in hospitalisation rates and how to further reduce hospitalisation rates for Japanese PD patients.

Phenotyping nocturnal polyuria: circadian and age-related variations in diuresis rate, free water clearance and sodium clearance

Background this study compares diuresis rate, sodium clearance and free water clearance (FWC) by age and time of day (nighttime vs. daytime) in subjects with and without nocturnal polyuria (NP) to determine whether these variables affect the phenotype of NP. Methods post hoc analysis of two prospective observational studies. Eight urine samples collected at 3-h intervals and a single blood sample were used to calculate daytime (10a/1p/4p/7p/10p) and nighttime (1a/4a/7a) diuresis rates, sodium clearance and FWC. Three mixed linear models were constructed for diuresis rate, sodium clearance and FWC using four predictor variables: NP status (present [nocturnal urine production >90 ml/h] vs. absent [≤90 ml/h]), time of day, age and study identification. Results subjects with NP experienced higher nighttime versus daytime diuresis rates, sodium clearance and FWC. Regardless of NP status, increased age was accompanied by an increase in the ratio of nighttime/daytime diuresis rate, nighttime sodium clearance and daytime sodium clearance. FWC showed a complex age effect, which was independent of time of day or NP status. Conclusions age-related increases in nighttime/daytime diuresis rate, 24-h sodium clearance and 24-h FWC are not specific to subjects with NP. The age-related surge in either nocturnal sodium clearance or nocturnal FWC may represent the relevant substrate for behavioural or pharmacologic interventions targeting sodium diuresis or free water diuresis, respectively. Increases in FWC in older age groups may reflect impaired circadian rhythmicity of endogenous AVP or changes in responsiveness of the aged nephron to water clearance.

Disorders of water and sodium homeostasis

Water intake and the excretion of water are tightly regulated processes that are able to maintain a near-constant serum osmolality. Sodium disorders (dysnatraemias—hyponatraemia or hypernatraemia) are almost always due to an imbalance between water intake and water excretion. Understanding the aetiology of sodium disorders depends on understanding the concept of electrolyte-free water clearance—this is a conceptual amount of water that represents the volume that would need to be subtracted (if electrolyte-free water clearance is positive) or added (if negative) to the measured urinary volume to make the electrolytes contained within the urine have the same tonicity as the plasma electrolytes. It is the concentration of the electrolytes in the urine, not the osmolality of the urine, which ultimately determines the net excretion of water. Hyponatraemia (serum sodium concentration <135 mmol/litre) is a common electrolyte disorder. It is almost invariably due to impaired water excretion, often in states where antidiuretic hormone release is (1) a normal response to a physiological stimulus such as pain, nausea, volume depletion, postoperative state, or congestive heart failure; or (2) a pathophysiological response as occurs with thiazide diuretics, other types of medications, or in the syndrome of inappropriate diuresis; with both often exacerbated in hospital by (3) inappropriate iatrogenic administration of hypotonic fluids. Hypernatraemia (serum sodium concentration >145 mmol/litre) is a common electrolyte disorder that occurs when water intake is inadequate to keep up with water losses. Since the thirst mechanism is such a powerful stimulus, hypernatraemia almost invariably occurs in the context of an illness and care that restricts the patient’s access to water. This chapter discusses the clinical features, management, and prevention of hyponatraemia and hypernatraemia.

Impaired Urine Dilution Capability in HIV Stable Patients

Renal disease is a well-recognized complication among patients with HIV infection. Viral infection itself and the use of some antiretroviral drugs contribute to this condition. The thick ascending limb of Henle’s loop (TALH) is the tubule segment where free water clearance is generated, determining along with glomerular filtration rate the kidney’s ability to dilute urine.Objective. We analyzed the function of the proximal tubule and TALH in patients with HIV infection receiving or not tenofovir-containing antiretroviral treatment in comparison with healthy seronegative controls, by applying a tubular physiological test, hyposaline infusion test (Chaimowitz’ test).Material & Methods. Chaimowitz’ test was performed on 20 HIV positive volunteers who had normal renal functional parameters. The control group included 10 healthy volunteers.Results. After the test, both HIV groups had a significant reduction of serum sodium and osmolarity compared with the control group. Free water clearance was lower and urine osmolarity was higher in both HIV+ groups. Proximal tubular function was normal in both studied groups.Conclusion. The present study documented that proximal tubule sodium reabsorption was preserved while free water clearance and maximal urine dilution capability were reduced in stable HIV patients treated or not with tenofovir.