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Background: Chronic kidney disease is associated with chronic inflammation and progressive loss of peripheral muscle strength and the ability to exercise, and these changes are highly pronounced in patients receiving hemodialysis (HD). We evaluated hand grip strength (HGS) and leg muscle strength (LMS) in patients receiving HD and attempted to identify factors associated with muscle strength., Methods: We screened HGS (opposite the fistula side) and LMS (both sides) in HD patients at a single center (n = 112) by using digital hand and leg dynamometers (T.K.K. 5401 and 5710e/5715, Takei Scientific Instruments Co. Ltd., Niigata, Japan)., Results: The mean age of patients was 62.6 years, and 73.2% of the patients were male. Diabetes was the cause of kidney failure in 50% of the patients, and the median HD vintage was 34 months. A total of 77.7% of patients reported that they participated in regular home-based exercise, and 29.5% of patients regularly participated in hospital-based resistance exercise. HGS and LMS showed good correlation ( r = 0.715, P < 0.001). HGS (25.1 vs. 17.0 kg) and LMS (30.1 vs. 20.4 kg) were greater in males ( P < 0.001 and P < 0.001, respectively) than in females. Older patients (≥ 60 years) showed less LMS than younger patients in both males and females ( P = 0.012 and P = 0.037, respectively), but HGS did not differ according to age. Patients performing regular home- or hospital-based exercise showed higher HGS than those who did not exercise (24.2 vs. 18.6 kg, P = 0.011), but LMS was not significantly different (29.3 vs. 23.6 kg, P = 0.185). Multiple linear regression analysis proved that male sex, younger age, and any type of exercise were factors associated with improved HGS and LMS. Groups of older age (≥ 60 years), male sex, and shorter duration of HD (< median) benefitted more from exercise., Conclusion: Sex, age, and exercise were the most important determinants of muscle strength in HD patients. We need to encourage patients to engage in regular home or group exercise from the beginning of dialysis and introduce new feasible forms of exercise for HD patients., Competing Interests: The authors have no conflicts of interest to disclose., (© 2021 The Korean Academy of Medical Sciences.)

A 68-year old man diagnosed with Middle East Respiratory Syndrome-Coronavirus (MERS-CoV) presented with multiple pneumonic infiltrations on his chest X-ray, and the patient was placed on a mechanical ventilator because of progressive respiratory failure. Urinary protein excretion steadily increased for a microalbumin to creatinine ratio of 538.4 mg/g Cr and a protein to creatinine ratio of 3,025.8 mg/g Cr. The isotope dilution mass spectrometry traceable serum creatinine level increased to 3.0 mg/dL. We performed a kidney biopsy 8 weeks after the onset of symptoms. Acute tubular necrosis was the main finding, and proteinaceous cast formation and acute tubulointerstitial nephritis were found. There were no electron dense deposits observed with electron microscopy. We could not verify the virus itself by in situ hybridization and confocal microscopy (MERS-CoV co-stained with dipeptidyl peptidase 4). The viremic status, urinary virus excretion, and timely kidney biopsy results should be investigated with thorough precautions to reveal the direct effects of MERS-CoV with respect to renal complications.

Some cases of Middle East Respiratory Syndrome-Coronavirus (MERS-CoV) infection presented renal function impairment after the first MERS-CoV patient died of progressive respiratory and renal failure. Thus, MERS-CoV may include kidney tropism. However, reports about the natural courses of MERS-CoV infection in terms of renal complications are scarce. We examined 30 MERS-CoV patients admitted to National Medical Center, Korea. We conducted a retrospective analysis of the serum creatinine (SCr), estimated glomerular filtration rate (eGFR), urine dipstick tests, urinary protein quantitation (ACR or PCR), and other clinical parameters in all patients. Two consecutive results of more than trace (or 1+) of albumin and blood on dipstick test occurred in 18 (60%) (12 [40%]) and 22 (73.3%) (19 [63.3%]) patients, respectively. Fifteen (50.0%) patients showed a random urine ACR or PCR more than 100 mg/g Cr. Eight (26.7%) patients showed acute kidney injury (AKI), and the mean and median durations to the occurrence of AKI from symptom onset were 18 and 16 days, respectively. Old age was associated with a higher occurrence of AKI in the univariate analysis (HR [95% CI]: 1.069 [1.013-1.128], P = 0.016) and remained a significant predictor of the occurrence of AKI after adjustment for comorbidities and the application of a mechanical ventilator. Diabetes, AKI, and the application of a continuous renal replacement therapy (CRRT) were risk factors for mortality in the univariate analysis (HR [95% CI]: diabetes; 10.133 [1.692-60.697], AKI; 12.744 [1.418-114.565], CRRT; 10.254 [1.626-64.666], respectively). Here, we report renal complications and their prognosis in 30 Korean patients with MERS-CoV.

It is known that blood pressure variability (BPV) can independently affect target organ damage (TOD), even with normal blood pressure. There have been few studieson chronic kidney disease (CKD) patients. We evaluated the relationship between BPV and TOD in a cross-sectional, multicenter study on hypertensive CKD patients. We evaluated 1,173 patients using 24-hr ambulatory blood pressure monitoring. BPV was defined as the average real variability, with a mean value of the absolute differences between consecutive readings of systolic blood pressure. TOD was defined as left ventricular hypertrophy (LVH) (by the Romhilt-Estes score ≥4 in electrocardiography) and kidney injury (as determined from an estimated glomerular filtration rate [eGFR]<30 mL/min/1.73 m(2) and proteinuria).The mean BPV of the subjects was 15.9±4.63 mmHg. BPV displayed a positive relationship with LVH in a univariate analysis and after adjustment for multi-variables (odds ratio per 1 mmHg increase in BPV: 1.053, P=0.006). In contrast, BPV had no relationship with kidney injury. These data suggest that BPV may be positively associated with LVH in hypertensive CKD patients.

Kidney transplantation and accompanying medical conditions may result in changes in body composition. Such changes have been evaluated in Caucasian recipients, but not in Asian recipients. Herein, we conducted a study on Asian recipients because Asians have a different body composition from Caucasians. A total of 50 Asian recipients was enrolled as a prospective cohort. Using bioelectrical impedance analysis, body composition (muscle and fat mass) was assessed after 2 weeks (baseline), and at 1, 3, 6, 9, and 12 months following kidney transplantation. To find predictors related to changes, the data were analyzed by multivariate analysis using forward selection. All of the patients had good graft function during the study period. Patients gained approximately 3 kg within 1 yr of kidney transplantation. The proportion of muscle mass significantly decreased (P(trend) = 0.001) and the proportion of fat mass significantly increased over time (P(trend) = 0.002). The multivariate results revealed that male recipients, deceased donor type, and low protein intake were associated with an increase in fat mass and a decrease in muscle mass. The results from this study may help to investigate differences in body composition changes between races, as well as the factors related to these changes.

Race and ethnicity are influential in estimating glomerular filtration rate (GFR). We aimed to find the Korean coefficients for the Modification of Diet in Renal Disease (MDRD) study equations and to obtain novel proper estimation equations. Reference GFR was measured by systemic inulin clearance. Serum creatinine (SCr) values were measured by the alkaline picrate Jaffé kinetic method, then, recalibrated to CX3 analyzer and to isotope dilution mass spectrometry (IDMS). The Korean coefficients for the 4 and 6 variable MDRD and IDMS MDRD study equations based on the SCr recalibrated to CX3 and to IDMS were 0.73989/0.74254 and 0.99096/0.9554, respectively. Coefficients for the 4 and 6 variable MDRD equations based on the SCr measured by Jaffé method were 1.09825 and 1.04334, respectively. The modified equations showed better performances than the original equations. The novel 4 variable equations for Korean based on the SCr measured and recalibrated to IDMS were 107.904×SCr(-1.009)×age(-0.02) (×0.667, if woman) and 87.832×SCr(-0.882)×age(0.01) (×0.653, if woman), respectively. Modified estimations of the MDRD and IDMS MDRD study equations with ethnic coefficients and the novel equations improve the performance of GFR estimation for the overall renal function.