The aging hypertensive kidney: pathophysiology and therapeutic options

Computed tomography evaluation of renal artery morphometry in adults. The impact of age and gender

Objectives:

To determine the effect of age and gender on diameters and lengths of the renal arteries.

Methods:

This is a retrospective study. A total of 50 asymptomatic volunteers were selected randomly and scanned by multi-detector CT to assess the diameters and lengths of the renal arteries. The study conducted at King Abdulaziz Specialized Hospital (KAASH) and King Faisal Hospitals, Taif, Saudi Arabia between October 2017 and March 2018. The lengths and diameters of the main arteries were measured and compared to age and gender of the participants.

Results:

The mean length of right renal artery was significantly longer than the left one (4.47±.70 versus 3.714±.68 cm, p<0.001). Length of right and left renal arteries were significantly higher in males than females (p=0.02 and p =0.03). Diameters of both left and right renal arteries were higher in males than females (5.482±1.37 versus 5.288±1.09 cm, and 5.544±1.14 versus 5.188±1.05 cm). The diameters of renal arteries varied significantly with age, specifically in elders (p=0.001).

Conclusion:

The mean length and mean diameter were significantly different between females and males, and between left and right main renal arteries. Age and gender have a significant impact on the length and diameters of main renal arteries.

The effect of Ramadan fasting on kidney function in patients with chronic kidney disease

PURPOSE

Because of the increase in globalization, clinicians all over the world are confronted the questions about safety of Ramadan fasting. However, there is no clear information about whether there is an obstacle for fasting patients with chronic disease. Hence, in the present study, we aimed to investigate the effects of Ramadan fasting on kidney and the factors affecting this relationship in patients with chronic kidney disease.

METHODS

This study involving 117 patients [36 females, 81 males; mean age, 60 (46.0-70.0) years] with stage 2-3 chronic kidney and fasting. Patients were evaluated every 10 days for acute kidney injury (AKI) in Ramadan month. And, patients with acute kidney injury and patients without AKI were grouped.

RESULTS

When the patients were evaluated for AKI, we observed that in 27 patients had acute kidney injury. While patients without AKI fasted for more days (p < 0.001), urea levels and frequency of hypertension were higher in the group with AKI (p = 0.019; p = 0.025 respectively). We also performed univariate and multiple binary logistic regression analysis to identify the risk factors of AKI. Hypertension and number of fasting day were found to be predictive of AKI (p = 0.02; p < 0.001 respectively).

CONCLUSIONS

We found a significant relationship between hypertension, the number of fasting days and acute kidney injury. Patients with chronic kidney damage and hypertension should be evaluated more carefully, informed about the importance of hydration after fasting and should be followed frequently for AKI.

Relationship between diurnal blood pressure and renal histopathological changes in white coat hypertension

BACKGROUND

Multiple epidemiological studies have clearly demonstrated the macrovascular risks associated with white coat hypertension (WCH) or sustained hypertension (SH). In patients with WCH, there is no literature available on renal histopathological changes and that on blood pressure pattern and native kidney outcome is scant. We aimed to clarify the relationship between blood pressure variables and pathological features of kidney biopsies in living kidney donors with WCH.

METHODS

This cross-sectional study included living kidney donors with WCH (n = 10) and SH (n = 10), and 20 healthy kidney donors with similar demographic features (control group). Kidney allograft biopsy samples were obtained during transplantation and chronic glomerular, vascular and tubulointertitial changes were semiquantitatively scored according to the Banff classification.

RESULTS

The mean age of the 20 hypertensive subjects (Group 1) and controls (Group 2) was 59.3 ± 8.5 versus 59.6 ± 7.6 years and almost half were female. There was no difference in renal function parameters between the groups; however, kidney histopathology in Group 1 was worse than Group 2 with a chronicity index of 2.80 ± 1.67 versus 1.75 ± 1.16 (p = 0.02). There was no difference between histopathological scores of patients with WCH or SH (chronicity index: 2.60 ± 1.43 vs. 2.70 ± 1.70, p = 0.88). Night-to-day mean arterial pressure (MAP) ratio was significantly associated with chronicity index in patients with WCH. Moreover, WCH patients with non-dipper hypertensive pattern had a worse chronicity index.

CONCLUSIONS

Significant histopathological alterations in the kidney were observed in patients with WCH and SH, and were accentuated in WCH patients with non-dipper blood pressure pattern.

Living Donor Kidney Transplantation: Facilitating Education about Live Kidney Donation--Recommendations from a Consensus Conference

The Best Practice in Live Kidney Donation Consensus Conference held in June of 2014 included the Best Practices in Living Donor Education Workgroup, whose charge was to identify best practice strategies in education of living donors, community outreach initiatives, commercial media, solicitation, and state registries. The workgroup's goal was to identify critical content to include in living kidney donor education and best methods to deliver educational content. A detailed summary of considerations regarding educational content issues for potential living kidney donors is presented, including the consensus that was reached. Educational topics that may require updating on the basis of emerging studies on living kidney donor health outcomes are also presented. Enhancing the educational process is important for increasing living donor comprehension to optimize informed decision-making.

'Normal for now' or 'at future risk': a double standard for selecting young and older living kidney donors

Transplant centers medically evaluate potential living kidney donors in part to determine their baseline remaining lifetime risk for end stage renal disease (ESRD). If baseline risk is increased by the presence of a risk factor for ESRD, donation is often refused. However, as only about 13% of ESRD occurs in the general population by age 44, a normal medical evaluation cannot be expected to significantly reduce the 7% lifetime risk for a 'normal' 25-year-old black donor or the 2-3% risk for a similar white donor. About half of newly diagnosed ESRD in the United States occurs by age 65, and about half of that is from diabetic nephropathy, which takes about 25 years to develop. Therefore, the remaining baseline lifetime risk for ESRD is significantly lower in the normal, nondiabetic 55-year-old donor candidate. Some older donors with an isolated medical abnormality such as mild hypertension will be at lower or about the same overall baseline lifetime risk for ESRD as are young 'normal' donor candidates. Transplant centers use a 'normal for now' standard for accepting young donors, in place of the long-term risk estimates that must guide selection of all donors.

Renal function improves in liver transplant recipients when switched from a calcineurin inhibitor to sirolimus

Sirolimus (Rapamune; Wyeth-Ayerst, Philadelphia, PA) is a newer immunosuppressive drug with no known acute or chronic nephrotoxic effects; however, limited data are available in liver transplant recipients. We prospectively evaluated changes in renal function in liver transplant recipients after conversion from a calcineurin inhibitor to sirolimus monotherapy. We measured serial serum creatinine levels in liver transplant recipients with chronic nephrotoxicity caused by calcineurin inhibitors before and after conversion to sirolimus therapy. Estimated glomerular filtration rate (eGFR) was calculated from the Modification of Diet in Renal Disease formula. Change in eGFR over time, incidence of acute hepatocellular rejection, and adverse events while being administered sirolimus monotherapy were recorded. Mean interval between liver transplantation and initiation of sirolimus therapy was 310 weeks (range, 9 to 780 weeks). Of 21 patients included in our study, 18 patients were converted to sirolimus monotherapy and 3 patients were switched to sirolimus and low-dose steroid therapy. Patients were followed up for a mean of 66.8 +/- 38.9 (SD) weeks after conversion. Renal function improved in 71% of patients (15 of 21 patients). Median eGFR improved significantly from 34 mL/min/1.73 m2 at the time of conversion to 43 mL/min/1.73 m2 at the last follow-up (27% increase in eGFR; P = 001). Median monthly change in eGFR was from -0.25 mL/min/1.73 m2 pre-sirolimus therapy to +1.28 mL/min/1.73 m2 post-sirolimus therapy (P =.09). Adverse events were mostly mild and self-limited. Only 1 patient developed biopsy-proven acute cellular rejection, which was treated with sirolimus and mycophenolate mofetil. Two patients discontinued sirolimus therapy because of toxicity (oral ulceration, 1 patient; interstitial pneumonitis, 1 patient). Renal function improved significantly in the majority of liver transplant recipients with renal insufficiency caused by calcineurin inhibitors when converted to sirolimus therapy. Sirolimus monotherapy provided adequate immunosuppression with a low incidence of acute cellular rejection and minimal adverse events.

Changes in renal autacoids and hemodynamics associated with aging and isolated systolic hypertension

The aging kidney is characterized by a decrease in renal blood flow and glomerular filtration rate mainly due to glomerulosclerosis. Nevertheless, even in the presence of these changes, the kidney maintains its functionality until advanced age. However, there is a tendency towards greater renal vasoconstriction in the elderly as compared with young individuals. This occurs either in physiological circumstances such as physical exercise, or in disease manifestations, such as the effective circulatory volume depletion that develops, for example, in heart failure. This tendency may be secondary to the reduction of renal autacoid modulatory capacity, particularly at the vasodilating prostaglandin level. In an acute experimental model we could demonstrate that, in the healthy elderly, the renal response to adrenergic activation by mental stress is characterized by a prolonged and pronounced vasoconstriction. In addition to this, in elderly patients affected by isolated systolic hypertension, we demonstrated an impairment of renal hemodynamic and humoral adaptation capacity in response to adrenergic activation and blood pressure increase. In the presence of sudden blood pressure increase, the kidney of these patients responds with a passive vasodilation and a glomerular filtration rate increase without any activation of humoral modulatory substances. The impairment in renal adaptation capacity may predispose these patients to renal injury, particularly in the presence of the many hypertensive peaks which characterize everyday life of elderly individuals. In conclusion, these results show that renal adaptation capacity of elderly patients with isolated systolic hypertension is completely lost. Further studies will elucidate whether antihypertensive treatment per se, or specific classes of antihypertensive drugs, are able to revert this impairment.

Onset of glomerular hypertension with aging precedes injury in the spontaneously hypertensive rat

The changes in renal hemodynamics that develop with aging in spontaneously hypertensive rats (SHR) were examined. Micropuncture studies revealed that glomerular capillary pressure was elevated in SHR at 9 mo of age compared with 3-mo-old SHR and 9-mo-old normotensive Wistar-Kyoto rats. Glomerular hypertension developed because of a small increase in systemic blood pressure and a decline in preglomerular vascular resistance, allowing transmission of elevated systemic pressure to the glomerular capillaries. The hemodynamic alterations were not a compensatory response to injury, inasmuch as vascular and glomerular morphology were normal in 9-mo-old SHR. To determine the mechanism of these changes, the activity of several vasoactive systems was examined. Similar changes in renal hemodynamics were observed in young and old SHR after blockade of nitric oxide production and after intravenous administration of endothelin. However, ANG II produced a proportionally greater reduction in glomerular filtration rate than renal blood flow in older SHR. These data suggest that reduced endogenous activity of the renin-angiotensin system leads to glomerular hypertension in aging SHR. Late development of glomerular hypertension may contribute to the subsequent appearance of glomerular sclerosis and progressive renal failure in these rats.

Safety of gadodiamide injection in two different age groups

A meta-analyses was performed to evaluate the safety of gadodiamide injection (OM-NISCAN) for magnetic resonance imaging in two different age groups (< 65 years; > or = 65 years). Data on vital signs, clinical laboratory parameters, and subjectively experienced adverse events were reviewed for 734 patients included in 19 European Phase II and III trials with gadodiamide injection (0.1 mmol/kg body weight or 0.3 mmol/kg body weight) used in magnetic resonance imaging. One hundred sixty-four patients were 65 years of age or older. No statistically significant differences were shown between this population and the population younger than 65 years of age with respect to vital signs or clinical laboratory parameters. A total of 48 adverse events, discomfort excluded, were reported, with no significant difference in frequency between the two age groups. Injection-associated discomfort was significantly (P = .0025) more frequent in the younger (9.2%) than in the older group (2.5%). Gadodiamide injection is in conclusion a safe contrast medium in older as well as in younger patients.

ACE inhibitors. Differential use in elderly patients with hypertension

High blood pressure (BP) in the elderly must not be ignored as a normal consequence of aging. The criteria for the diagnosis of hypertension and the necessity to treat it are the same in elderly and younger patients. The aim of treatment of elderly hypertensive patients is to decrease BP safely and to reduce risk factors associated with cerebrovascular, cardiovascular and renal morbidity and mortality. The treatment of elderly hypertensive patients should be adjusted according to the needs of the individual, based upon age, race, severity of hypertension, co-existing medical problems, other cardiovascular risk factors, target-organ damage, risk-benefit considerations and costs. In addition to the elevated BP, other cardiovascular risk factors include smoking, glucose intolerance, hyperinsulinaemia, dyslipidaemia, hypercreatininaemia, peripheral vascular disease, left ventricular hypertrophy, and microalbuminuria (or albuminuria). Thus, the choice of initial antihypertensive therapy in elderly hypertensive patients should be based not only on the expected response, but also on the effects of therapy on lipid, potassium, glucose and uric acid levels, and left ventricular anatomy and function. Co-existing medical conditions (such as asthma, diabetes mellitus, heart failure, renal failure, gout, coronary artery disease, hyperlipidaemia and peripheral vascular disease) are major determinants for the selection of antihypertensive medications. With previous therapies (diuretics, beta-blockers, etc.), good BP control in the elderly was associated with clear and statistically significant reductions in stroke-related morbidity and mortality, but the overall effects on cardiovascular and renal complications of hypertension was either more variable or less obvious. Angiotensin converting enzyme (ACE) inhibitors are not only efficacious antihypertensive agents in the elderly, but also appear promising in counteracting some of the cardiovascular and renal consequences of hypertension. They are well tolerated and have a relatively low incidence of adverse effects. ACE inhibitors possess ancillary characteristics that are potentially beneficial for many elderly patients, including reduction of left ventricular mass, lack of metabolic and lipid disturbances, no adverse CNS effects, no risk of induction of heart failure, and a low risk of orthostatic hypotension. Since ACE inhibitors may improve perfusion to the heart, kidney and brain, they are well worth considering for the treatment of elderly patients with hypertensive target organ damage, especially in patients with heart failure, and diabetic patients with early nephropathy.

Accelerated hypertension and nephroangiosclerosis associated with antiphospholipid syndrome. Report of two cases and review of the literature

We describe two patients with the primary antiphospholipid syndrome who presented with severe hypertension. Renal biopsy specimen provided histologic evidence of intra-renal vascular disease with intravascular microthrombosis and nephrosclerosis, without feature of proliferative glomerulopathy. Accelerated hypertension and nephroangiosclerosis might indeed be one of the complications associated with anticardiolipin antibodies. The mechanism responsible might be the interaction of anticardiolipin antibodies, platelets and endothelial cell leading to microthrombi formation and increased local mitogenic activity that attract and stimulate neighbouring smooth muscle cell and fibroblast proliferation.

Abnormal renal function in isolated systolic hypertension correlation with ambulatory blood pressure

Does ambulatory blood pressure correlate with the renal function damage better than clinic blood pressure in isolated systolic hypertension, as has been reported in other target organ involvement in combined systolic/diastolic hypertension? We investigated the correlation of serum beta-2 microglobulin concentration and both 24-h urine beta-2 microglobulin concentration and excretion as measures (suggestive) of glomerular filtration rate and tubular reabsorption, respectively with both ambulatory and clinic blood pressure in 19 health normotensive (68 +/- 4.9 years) and 50 isolated systolic hypertensive elderly individuals (69 +/- 5.4 years). Serum beta-2 microglobulin concentration and 24-h urine beta-2 microglobulin concentration and excretion were higher in the isolated systolic hypertension than in the normotensive group (P < 0.05). In isolated systolic hypertensive patients, 24-h urine beta-2 microglobulin concentration and excretion were related to ambulatory blood pressure (r = 0.32-0.40, P < 0.05), but not to clinic blood pressure; waking systolic blood pressure had the strongest correlation with both 24-h urine beta-2 microglobulin concentration and excretion among derivatives of ambulatory blood pressure (r = 0.35 and 0.40, P < 0.05). We conclude that ambulatory blood pressure, especially waking systolic blood pressure, is superior to clinical blood pressure in predicting renal function impairment, in isolated systolic hypertensive patients.

Antihypertensive efficacy and acceptability of perindopril in elderly hypertensive patients

The antihypertensive efficacy and acceptability of perindopril, an angiotensin-converting enzyme (ACE) inhibitor, was evaluated in 2,927 elderly (> or = 70 years) hypertensive patients in general practice, as part of an open 6-month trial conducted on a total of 23,460 patients with mild-to-moderate hypertension. Patients were ambulatory and selected if diastolic blood pressure (DBP) was between 94 and 115 mm Hg and no serious illness or ACE inhibitor intolerance was known. Perindopril was started at 2 or 4 mg once daily and, if supine DBP remained > 90 mm Hg, the daily dose could be doubled after 1 or 3 months (or a diuretic added if perindopril titration reached 8 mg). At entry, the 2,927 patients (65% females) were on average 74 years old, body weight was 68.2 kg, duration of hypertension was 9.4 years, and prior antihypertensive treatment was present in 78%. Percentage of normal DBP (< or = 90 mm Hg) was 69% at 1 month, 86% at 3 months (in patients on perindopril alone), and 94% at 6 months. At 6 months the reduction of systolic blood pressure and DBP was 28 and 16.6 mm Hg, respectively. Of the 2,927 patients at entry, 8.6% dropped out during the trial, including 6.1% due to side effects. Cough was the most common symptom (8.9%) leading to withdrawal in 3.4% of cases. In one patient, serum creatinine increased (3-fold at 1 month), but overall no significant variation of renal function occurred, as shown by stable plasma creatinine and potassium levels.

Hypertension in the elderly with a special focus on treatment with angiotensin-converting enzyme inhibitors and calcium antagonists

Age-related changes (e.g., decrease in plasma renin activity and total body potassium, increase in plasma catecholamines, volume depletion) need to be taken into account when selecting an antihypertensive agent for the elderly patient. A number of large scale clinical trials (e.g., Systolic Hypertension in the Elderly Program, Veterans Administration Cooperative Study, European Working Party on High Blood Pressure in the Elderly) have demonstrated that antihypertensive therapy with diuretics substantially reduced cardiovascular mortality and stroke incidence. However, since diuretics, even potassium-sparing agents, may induce hypokalemia, newer antihypertensive agents (angiotensin-converting enzyme [ACE] inhibitors and calcium antagonists) may also be appropriate as first-line monotherapy for this patient population. ACE inhibitors are effective antihypertensive agents and are associated with a lower rate of adverse effects than diuretics, beta blockers, and centrally acting agents. Nevertheless, periodic monitoring of serum potassium, creatinine levels, and renal function is advisable. An important feature of calcium antagonists is that they lower blood pressure with no negative effect on serum lipids or glucose metabolism. Typically, they have few side effects, peripheral edema being the most commonly reported. A recent double-blind randomized study comparing a new sustained release nifedipine formulation and the ACE inhibitor lisinopril found the 2 drugs equivalent in efficacy with no differences in the rate of adverse events.

Biocultural predictors of age increases in adult blood pressure among Samoans

A five-year follow-up sample of 509 adult male and female Samoans experiencing modernization in American Samoa was studied to determine the relation between baseline biocultural factors and follow-up blood pressure level. Analyses were stratified by sex and baseline age: 18-44 and ≥45 years. Baseline factors in the predictive models included blood pressure level, sum of skinfolds, age, education level, and reported salt intake. This Samoan adult sample was characterized by high prevalence of overweight at all ages, continual fat gain, and high incidence of overweight in young adults over five years. Blood pressure levels were moderate in young adults considering the adiposity, although almost one-third of those ≥45 years of age were hypertensive. In young adults baseline adiposity was the most important predictor of follow-up blood pressure, whereas in older adults age itself was most important. As age increases, physiologic blood pressure regulation may become less labile due to long-term adiposity and salt intake and lead to persistent elevations of blood pressure.