A study of urinary sodium and potassium excretion rates among urban and rural Zulus and Indians

A study was carried out to evaluate the relationship between blood pressure, plasma renin activity, serum aldosterone and patterns of urinary sodium and potassium excretion rates in urban Zulus, rural Zulus and Indians in order to explain the high prevalence of hypertension in the urban adult Zulu (25%) compared to the rural adult Zulu (10%). Urinary sodium and potassium were not significantly different between urban and rural Zulus. There was no association between sodium excretion and blood pressure. Urinary potassium correlated negatively with blood pressure in rural Zulus and Indians but not in urban Zulus. The urinary sodium:potassium ratio was significantly lower in rural Zulus than in urban Zulus. The sodium:potassium ratio of Indians was not significantly different from that of Zulus. Plasma renin activity levels were significantly lower in urban than in rural Zulus. This difference is an enigma but may be due to an environmental factor. Serum aldosterone correlated positively with plasma renin activity and negatively with the urinary sodium:potassium ratio.     

Lack of association of Human T-cell Lymphotrophic Virus Type 1(HTLV-1) infection and rheumatoid arthritis in an endemic area

 In South Africa the association of HTLV-1 infection with myelopathy is well described in Kwa Zulu Natal, which is an endemic area for HTLV-1 infection. Japan also has a high background prevalence of HTLV-1 infection, and a significant association of HTLV-1 infection with rheumatoid arthritis has been reported. This study was undertaken to determine whether there was an association with HTLV-1 infection among black Africans with rheumatoid arthritis (RA) in Kwa Zulu Natal, South Africa. A randomly selected group of 110 black people with RA were studied. The age, sex and duration of disease were recorded and a rheumatoid factor test was performed. The presence of antibodies to HTLV-1 was assessed using an enzyme-linked immunosorbent assay. The integration of proviral DNA in peripheral blood monocytes was also studied using the polymerase chain reaction (PCR). Control data were available from a previously reported community-based study of 1018 subjects from the same geographical area. None of the 110 patients studied were positive for HTLV-1 infection by serology or by PCR. Although HTLV-1 infection is reported as a possible triggering agent for RA in Japan, we failed to detect any excess of HTLV-1 infection in black Africans with RA. Our findings are in agreement with observations in the USA and Europe. Received: 27 December 2001 / Accepted: 22 July 2002 Acknowledgements This project was supported by a grant from the University of Natal Research Fund. We wish to thank Professor A.I. Bhigjee for his encouragement to undertake this study and Sister N.G. Mkhize for assistance with the study.     

Urinary sodium and potassium excretion, body mass index, alcohol intake and blood pressure in three Japanese populations

Standardised data on blood pressure, 24 hour urinary electrolyte excretion and other lifestyle factors were obtained in three Japanese populations as part of the INTERSALT study. Urinary sodium excretion and sodium/potassium ratio were significantly (P less than 0.01) higher in Toyama (a semi-rural area in central Japan) than in Tochigi (a rural area 100 km north of Tokyo) and Osaka. There were also significant (P less than 0.01) differences between the centres in diastolic blood pressure (highest in Toyama), although systolic pressure was similar in all three centres. Average potassium excretion was low (46 mmol/day), and the prevalence of both heavy alcohol drinking (greater than or equal to 300 ml/week) and smoking was high in men (33% and 61% respectively); compared with other countries, there were favourable levels of body mass index (mean 22.4 kg/m2). Despite a recent decline in sodium consumption in Japan, which has been accompanied by a fall in blood pressure levels, in the prevalence of hypertension and also in stroke mortality, average sodium excretion in the three centres was high compared to other countries (187 mmol/day). Applying overall INTERSALT regression coefficients to the Japanese data, suggested that further falls in sodium intake together with a modest increase in potassium intake and a reduction (in men) in the prevalence of heavy alcohol drinking could have an important impact on average blood pressures and the prevalence of hypertension. It can be expected that these nonpharmacological approaches to improved blood pressure levels will be accompanied by continued reductions in mortality from stroke.     

Correlates of blood pressure in rural and urban Za?re

Blood pressure and anthropometric characteristics were studied in 312 rural and 675 urban Bantu of Za?re aged 10 years and more; proteinuria and the urinary sodium to potassium ratio were determined. On average, systolic and diastolic pressure were higher in rural than in urban Bantu, and rose with advancing age in both populations. However, rural Bantu were older, lighter and smaller, and had a lower sodium:potassium ratio than urban Bantu. Using multiple regression analysis, systolic and diastolic pressures correlated positively with age, weight, pulse rate, sex and sodium:potassium ratio; diastolic pressure also correlated negatively to height. After adjusting blood pressure for these independent correlates, systolic pressure remained significantly higher in rural Bantu. However, no significant difference persisted between the two populations after adjusting blood pressure for age alone. The prevalence of hypertension in rural and urban Bantu increased with age and was 14.2 and 9.9%, respectively, for participants at least 20 years old; women were more affected in the rural area, whereas men were more affected in the urban population. The occurrence of proteinuria was higher in rural Bantu than in urban; it was similar in participants with and without definite hypertension. It is suggested that higher blood pressure in the rural setting was mostly accounted for by the older age of the population.     

Seroprevalence of HIV infection in rural South Africa.

OBJECTIVES: To establish the prevalence of HIV infection in rural South Africa and to investigate demographic factors that influence this prevalence. DESIGN: An anonymous HIV seroprevalence survey was performed in conjunction with a population-based malaria surveillance programme. SETTING: The rural area of northern Natal/KwaZulu, South Africa. PARTICIPANTS: A total of 5023 black African participants were recruited by malaria surveillance agents during house-to-house visits; each house in an endemic malaria area is visited approximately once every 6 weeks. Participants included 4044 healthy and 979 febrile individuals (i.e., suspected of having malaria). MAIN OUTCOME MEASURES: HIV-1 and HIV-2 serological status, degree of mobility, age and sex. RESULTS: Sixty of the 5023 blood specimens were confirmed to be HIV-1-antibody-positive by Western blot, an overall prevalence of 1.2% (95% confidence interval, 0.9-1.5). None of the specimens was positive for HIV-2 antibodies. After adjusting for age, presence of fever and migrancy, women had a 3.2-fold higher prevalence of HIV-1 infection than men. HIV-1 infection was approximately three times more common among subjects who had changed their place of residence recently (2.9 versus 1.0%, P < 0.01). CONCLUSIONS: The prevalence of HIV-1 infection is higher among women than men resident in rural Natal/KwaZulu, South Africa. This is at least in part the result of oscillatory migration, particularly of men who work in urban areas but have families and homes in rural areas. Migration is associated with a higher prevalence of HIV-1 infection, suggesting that improving social conditions so that families are not separated and become settled in their communities is one way to help reduce the spread of HIV-1.     

拉萨市区藏族中老年人群高血压患病率调查

目的 了解拉萨市区藏族中老年人群高血压患病情况及影响因素。方法 采用在居民集中区普查的方法对4853例藏族中老年人群进行血压、血糖及体重指数等检查。结果 拉萨市区藏族中老年人群高血压患病率为40．68％，并且发现年龄与高血压患病率呈正相关；60岁以上老年人单纯收缩期高血压患病率明显增加，超重肥胖发生率及血糖异常率，高血压组明显高于正常血压组。高血压知晓率39．56％，治疗率29．64％，控制率9．68％。结论 西藏拉萨市区藏族中老年人高血压患病率高，与其特殊的地理环境、生活方式、过多脂肪和钠盐的摄入、运动量较少、低文化程度等有关。高血压知晓率、治疗率、控制率较低，必须采取干预措施。     

Prevalence and determinants of hypertension in the Algerian Sahara

BACKGROUND: In-Salah is a city-oasis located in the middle of the Algerian Sahara, a desert area whose drinking water has a high sodium content. No cardiovascular epidemiological studies have ever been conducted in this region. METHODS: A randomized sample of 635 men and 711 women, aged 40-99 years, was studied. Blood pressure measurements, combined with a clinical questionnaire that included educational and socio-economic data, and standard blood samples for the detection of dyslipidemia and diabetes mellitus, were collected. RESULTS: The mean age was 55 +/- 12 years. The prevalence of hypertension was 44% and was highly influenced by age, sex, skin colour, educational status, obesity and metabolic parameters. The higher prevalence of hypertension among black individuals was independent of socio-economic and educational levels, and of metabolic parameters. The presence of antihypertensive treatment was three times more frequent in women than in men, and there was no difference according to skin colour. Among treated subjects, 25% were well controlled, and this percentage was similar among both black and white individuals. CONCLUSION: Epidemiological studies in such an emergent population indicate that hypertension is a major public health problem. The high sodium content in drinking water in this region could play a major role in the development of hypertension.     

Rationale,design, and baseline characteristics of the Salt Substitute in India Study (SSiIS): The protocol for a double‐blinded,randomized‐controlled trial

Reduced‐sodium, added‐potassium salt substitutes have favorable effects on blood pressure, but have not been tested in India. The Salt Substitute in India Study (SSiIS) is a double‐blinded, randomized‐controlled trial designed to investigate the effects of reduced‐sodium, added‐potassium salt substitution to replace usual cooking salt use and blood pressure (BP) among hypertensive patients in rural India. The primary objective is to assess effects on systolic blood pressure at 3 months. The secondary objectives are to determine effects on diastolic blood pressure, urinary sodium, and potassium levels, and to determine acceptability of the intervention. Eligible individuals received usual salt (100% sodium chloride) or salt substitute (70% sodium chloride and 30% potassium chloride) to replace all salt required for cooking and seasoning in the household. A total of 502 participants aged ≥18 years with a history of hypertension were successfully recruited and randomized in a 1:1 ratio to intervention or control, between November 2019 and January 2020. Mean blood pressure at baseline was 133.5/83.6 mm Hg and 96% were using one or more blood pressure‐lowering medications. The overall mean average 24‐hour urinary sodium excretion was 2825 (SD, 1166) mg/L, which corresponds to a urinary salt excretion of 10.4 g/d. Baseline findings suggest sodium intake in this population significantly exceeds World Health Organization recommendations. The SSiIS trial has successfully recruited participants and is well placed to determine whether salt substitution is an effective means of lowering blood pressure for rural Indian patients with hypertension.     

Blood pressure and urinary cations in a Chinese population.

The prevalence of hypertension and the relationship between blood pressure, age, body mass index (BMI) and urinary cations from casual urine specimens were examined in 1,513 Chinese employees of a public utility company and non-medical personnel of a district hospital. The prevalence of hypertension, defined as systolic blood pressure greater than or equal to 140 or a diastolic blood pressure greater than or equal to 90 mmHg, or a past history of hypertension, was 17% in men and 5% in women. After excluding subjects who were on antihypertensive medication, age, body mass index, and urinary sodium/potassium ratio were independently and positively associated with blood pressure, while urinary potassium/creatinine ratio was inversely related to blood pressure. No association with urinary sodium or sodium/creatinine ratio was found. Higher mean blood pressure in men was accompanied by lower urinary potassium/creatinine and potassium concentration and higher sodium/potassium ratio, even though men had the same mean BMI when compared with women. A difference in potassium intake between the sexes may partly account for this finding. We conclude that in this Chinese population, whose dietary intake is more influenced by the West compared with Chinese in the Peoples' Republic of China, age and BMI are important determinants of blood pressure, together with potassium intake as reflected by urinary potassium excretion. No association of blood pressure with sodium excretion was demonstrated.     

汉中农村学童膳食钠、钾、钙的分布和来源分析

本文分析汉中农村208名初中一年级(12～16岁)学童三天24小时回忆法膳食调查资料。结果显示:本组儿童膳食中钠、钾、钙的平均摄入量分别为:钠5333.4mg/日,钾2311.3mg/日,钙513.4mg/日。钠主要来源于烹调用盐及咸菜类食物(占每日钠摄入总量90.5%);钾和钙的42.6%和34.2%分别来源于新鲜蔬菜,另39.2%和32.8%则来自谷类。说明汉中农民膳食结构不尽合理。这不利于儿童生长发育和身体康健,也不利于高血压的预防和治疗,有待积极加以改善。     

Urinary Dopamine Excretion and Renal Responses to Fenoldopam Infusion in Blacks and Whites

Dopamine is an endogenous natriuretic amine that contributes to the maintenance of sodium homeostasis. Deficiencies in the renal production of dopamine and the action of dopamine on renal tubular receptors have been observed in human hypertension and may contribute to salt sensitivity of blood pressure. Ethnic differences in the sodium‐to‐dopamine relationship may contribute to the higher prevalence of salt sensitivity in blacks. The authors assessed dopaminergic activity in two studies. In the first, daytime and nighttime excretion of sodium and dopamine were compared in 11 black and 17 white normotensive patients. No racial difference in the rate of sodium or dopamine excretion during either period was observed. In the second study, a graded infusion of the dopamine‐1 receptor agonist, fenoldopam, was performed in 14 black and 17 white normotensive patients. There was no racial difference in the natriuretic responses. Previously described lower rates of renal free water clearance and potassium excretion in blacks compared with whites were maintained during fenoldopam infusion, suggesting that dopamine is not a mediator of those differences. The authors conclude that there are no race‐related differences in dopamine excretion or activity in normotensive patients.     

Impacto del consumo de alimentos ultraprocesados en la enfermedad renal crónica

The modern diet is closely linked to the consumption of processed foods, causing an increase in the intake of salt, simple sugars, phosphorus and added potassium. This excess intake is associated with an increased risk of obesity, diabetes, hypertension and chronic kidney disease (CKD). CKD, which according to data from the ENRICA study affects 15% of the population, magnifies its impact due to the higher prevalence of diabetes and hypertension and due to limitations in the management of sodium and phosphorus. The intake of these products far exceeds the established recommendations, assuming 72% of total sodium, 25-35% of phosphorus, 12-18% of potassium and exceeding 10% of the caloric intake in simple sugars. Measures are necessary to reduce their contribution through nutritional advice, labeling review, education campaigns on healthy habits, fees and institutional actions that involve food safety agencies, industry, distribution and scientific societies.     

Prevalence of sustained hypertension and obesity in urban and rural school going children in Ludhiana

BACKGROUND: Increasing trend of hypertension is a worldwide phenomenon. The data on sustained hypertension in school going children is scanty in India. The present study was conducted to evaluate the prevalence of sustained hypertension and obesity in apparently healthy school children in rural and urban areas of Ludhiana using standard criteria. METHODS AND RESULTS: A total of 2467 apparently healthy adolescent school children aged between 11-17 years from urban area and 859 students from rural area were taken as subjects. Out of total 3326 students, 189 were found to have sustained hypertension; in urban areas prevalence of sustained hypertension was 6.69% (n=165) and in rural area it was 2.56% (n=24). Males outnumbered females in both rural and urban areas. The mean systolic and diastolic blood pressure of hypertensive population in both urban and rural population was significantly higher than systolic and diastolic blood pressure in their normotensive counterparts (urban normotensive systolic blood pressure:115.48+/-22.74 mmHg, urban hypertensive systolic blood pressure: 137.59+/-11.91 mmHg, rural normotensive systolic blood pressure: 106.31+/-19.86 mmHg, rural hypertensive systolic blood pressure: 131.63+/-10.13 mmHg, urban normotensive diastolic blood pressure: 74.18+/-17.41 mmHg, urban hypertensive diastolic blood pressure: 84.58+/-8.14 mmHg, rural normotensive diastolic blood pressure: 68.84+/-16.96 mmHg, rural hypertensive diastolic blood pressure: 79.15+/-7.41 mmHg). Overweight populationwas significantly higher in urban area. There were 287 (11.63%) overweight students and 58 (2.35%) were obese. In rural population overweight and obese students were 44 (4.7%) and 34 (3.63%) respectively. There was significant increase in prevalence of hypertension in both rural and urban population with increased body mass index in urban students; those with normal body mass index had prevalence of hypertension of 4.52% (n=96), in overweight it was 15.33% (n=44) and in obese it was 43.10% (n=25). In rural area, the overweight students showed prevalence of sustained hypertension in 6.82% (n=3) and in obese group it was 61.76% (n=21). None of the student with normal body mass index in rural area was found to be hypertensive. The mean body mass index of hypertensive population in both rural and urban areas was significantly higher than respective normotensive population (mean body mass index in urban normotensive group: 20.34+/-3.72 kg/m2, hypertensive group: 24.91+/-4.92 kg/m2; mean body mass index in rural normotensive group: 18.41+/-3.41 kg/m2, hypertensive group: 21.37+/-3.71 kg/m2, p<0.01). CONCLUSIONS: Prevalence of sustained hypertension is on the rise in urban area even in younger age groups. Blood pressure is frequently elevated in obese children as compared to lean subjects. This is possibly related to their sedentary lifestyle, altered eating habits, increased fat content of diet and decreased physical activities.     

Prevalence, awareness, treatment, and control of hypertension in rural adults from Liaoning Province, northeast China.

Liaoning Province is located in northeast China, which has distinct weather conditions, geographic characteristics and lifestyles compared with other regions of the country; the lifestyle differences are especially pronounced in the rural parts of this region, where there is a dearth of financial and other resources. However, information on the prevalence, awareness, treatment, and control of hypertension in these impoverished areas is very scarce. We therefore performed multistage cluster random sampling of a group of 29,970 adult residents (>or=5 years of residency; >or=35 years of age) of the rural portions of Liaoning Province from 2005 to 2006. The sampling included a survey on blood pressure and associated risk factors. The overall prevalence of hypertension in the community was 36.2%, and 73.0% of hypertensives were unaware of their condition. Among the total group of hypertensives, only 19.8% were taking prescribed medication to lower their BP, and 0.9% had controlled hypertension. Of all subjects, 46.4% did not think that high blood pressure would endanger their lives. As to the reasons given by hypertensives who were aware of their hypertension for not taking antihypertensive medication, 47.4% reported that they lacked knowledge about the mortality of hypertension. The average salt intake in hypertensives was 16.6+/-9.9 g/day, and the percentages of smoking (44.3%), drinking (31.7%) and salt intake>6 g/day (86.8%) in hypertensives were high. Logistic regression analysis indicated that the relative risks (95% confidence interval [CI]) of overweight, obesity, smoking, drinking, increased salt intake and family history of hypertension for hypertension were 1.95 (range, 1.82-2.08), 2.92 (2.40-3.55), 1.19 (1.12-1.27), 1.16 (1.08-1.25), 1.26 (1.20-1.33) and 2.85 (2.66-3.05), respectively. A higher education level was found to be a protective factor. In conclusion, the prevalence of hypertension in adults living in the rural parts of Liaoning Province was high, and the rates of awareness, treatment, and control were unacceptably low, which may have been due to unique geographical characteristics, unwholesome lifestyles, greater sodium intake, lower education levels, and genetic risk factors.     

The relative importance of genetic and environmental factors in hypertension in black subjects

Essential hypertension is the most important cardiovascular disease in black subjects. The types of presentation, the pattern of organ involvement and the subsequent complications are similar in black races. The response (or lack of response) to different types of treatment are also alike in blacks when compared with caucasians. Striking racial differences are observed in the plasma and intracellular electrolytes, cation transmembrane transport, salt taste threshold, plasma renin activity and urinary kallikrein activity. The similarities within the black racial groups are very likely to be genetic, although the pattern of inheritance remains controversial. Differences, however, occur in the prevalence and severity of the disease among the black racial groups. That these differences are due partly to environmental causes can not be disputed because even within the same ethnic groups changing patterns are observed in the prevalence of hypertension, in the course of urbanization of rural communities, or on moving from a previously rural to an urban environment. Consequently, genetic factors may be the only important considerations in the severity of hypertension in black subjects.     

Anthropometric and lifestyle factors associated with white-coat, masked and sustained hypertension in a Chinese population

OBJECTIVE: We investigated to what extent anthropometric and lifestyle factors contributed to the classification of Chinese individuals into groups with white-coat, masked and sustained hypertension (HT). METHODS: We measured the office and ambulatory blood pressure (BP) in 694 Chinese enrolled in the JingNing population study (45.7% men; mean age, 48.4 years). In multivariate-adjusted analyses, we determined the correlates of both types of BP and the factors contributing to white-coat HT (conventional and daytime BP > or =140/90 and <135/85 mmHg, respectively), masked HT (<140/90 and > or =135/85 mmHg) and sustained HT (> or =140/90 and > or =135/85 mmHg), relative to normotension (<140/90 and <135/85 mmHg). RESULTS: In continuous analyses, the conventional and daytime BPs were positively associated with age, body mass index and urinary sodium, and inversely with urinary potassium. The prevalence of white-coat, masked and sustained HT was 7.8, 10.8, and 35.0%, respectively. In line with the continuous analyses, the risk of sustained hypertension increased with age [odds ratio (OR), 2.11 per 10 years], body mass index (OR, 1.27 per 1 kg/m2) and urinary sodium (OR, 1.18 per 50 mmol/day), but was inversely associated with urinary potassium (OR, 0.34 per 25 mmol/day). Furthermore, the risk of white-coat and masked HT increased with age (OR, 1.79 and 1.40, respectively) and body mass index (OR, 1.14 and 1.12). Women were less likely to have masked hypertension than men (OR, 0.39). CONCLUSIONS: Sex, age, body mass index, and urinary sodium and potassium excretion contribute to the risk of white-coat, masked and sustained HT in Chinese.     

Echocardiographic left ventricular mass and electrolyte intake predict arterial hypertension

OBJECTIVE: To identify predictors of arterial hypertension. PATIENTS: One hundred thirty-two normotensive adults from a large employed population. METHODS: Echocardiography, standard blood tests, and 24-hour urine collection, at baseline and after an interval of 3 to 6 years (mean, 4.7 +/- 0.8 years). RESULTS: At follow-up, 15 subjects (11%; 7 men, 8 women) had a systolic blood pressure greater than 140 mm Hg or a diastolic blood pressure greater than 90 mm Hg or both (mean, 143 +/- 7 and 87 +/- 6 mm Hg, respectively). At baseline, subjects who developed hypertension had a greater left ventricular mass index than those who did not (92 +/- 25 compared with 77 +/- 19 g/m2 body surface area; P less than 0.005) and higher 24-hour urinary sodium/potassium excretion ratio (3.6 +/- 1.7 compared with 2.6 +/- 1.4; P less than 0.04); there were no differences in race, initial age, systolic or diastolic blood pressure, coronary risk factors, or plasma renin activity. The likelihood of developing hypertension rose from 3% in the lowest quartile of sex-adjusted left ventricular mass index to 24% in the highest quartile (P less than 0.005); a parallel trend was less regular for quartiles of the sodium/potassium excretion ratio (P less than 0.04). In multivariate analyses, follow-up systolic pressures in all subjects and in the 117 who remained normotensive were predicted by initial age, systolic blood pressure, black race, and sex-adjusted left ventricular mass index; final diastolic blood pressure was predicted by its initial value, plasma triglyceride levels, urinary sodium/potassium ratio, low renin activity, black race, and plasma glucose level. CONCLUSIONS: Echocardiographic left ventricular mass in normotensive adults is directly related to the risk for developing subsequent hypertension. Left ventricular mass improves prediction of future systolic pressure, whereas diastolic pressure is more related to initial metabolic status. Black race is also an independent determinant of higher subsequent blood pressure.     

Prevalence, awareness, treatment, and control of hypertension among adults in Beijing, China

Hypertension is an important modifiable risk factor for cardiovascular diseases. This study aimed to determine the up-to-date prevalence, awareness, treatment, and control of hypertension, and their related influencing factors in adults in Beijing, China. A cross-sectional study was conducted in 2008. A total of 5760 adults aged 18-79 years were selected from the general population. Data from a standardized questionnaire, physical examination, and blood sample were obtained. The prevalence of hypertension was 35.5% (41.8% in men, 30.9% in women) and increased with age in both sexes. The prevalence was similarly high in urban (35.6%) and in rural (34.9%) areas. Body mass index (BMI) and waist circumference were independently associated with hypertension. Participants with diabetes and/or dyslipidemia had higher prevalence of hypertension than their counterparts. Among hypertensive patients, 42.5% were aware of the diagnosis, 35.9% received treatment, and 11.8% had hypertension control. Awareness and treatment of hypertension were low in men, young people, and rural residents. Control of hypertension was lower in older people and those with lower educational attainment. High waist circumference (central obesity) resulted in low control of hypertension (odds ratio = 0.45). Our findings underscore the urgent need to develop a comprehensive health strategy for the prevention, detection, and control of hypertension to avert the cardiovascular disease epidemic in Beijing.     

Racial differences of parameters associated with blood pressure levels in children—The Bogalusa Heart Study

Racial differences in prevalence of essential hypertension are well known. In order to explore these differences at an early age in terms of etiology, we investigated schoolchildren in an entire, biracial community. A sample of 278 children, stratified by diastolic (fourth-phase) blood pressure and specific for age, race, and sex, was reexamined 1--2 yr after initial observation for the following: (1) a physical examination and urinalysis to exclude secondary hypertension; (2) 24-hr urine sodium, potassium, plasma renin activity, and serum dopamine beta-hydroxylase; (3) 1-hr oral glucose tolerance test; and (4) heart rate and blood pressure at rest and under standarized physical stress. We found that 24-hr urine sodium was positively associated with blood pressure level as measured on the same day for the high blood pressure strata of black children. Urine potassium excretion was lower in blacks than in whites, although their intakes seemed equal. In the high blood pressure strata especially, black boys had lower renin activity than whites, and the resting-supine and stressed systolic blood pressures were higher in black boys than in any other group. In these black boys, resting and stressed systolic pressures were negatively related to plasma renin activity. On the other hand, dopamine beta-hydroxylase levels in white children were higher than in blacks for all blood pressure strata, and in the high blood pressure strata white children had higher 1-hr glucose levels and faster resting heart rates than black children. Different mechanisms may play a role in and contribute to the early stage of essential hypertension.     

Race and sex differences in asleep blood pressure: The Coronary Artery Risk Development in Young Adults (CARDIA) study

Nocturnal hypertension and non‐dipping blood pressure are each associated with increased risk of cardiovascular disease. We determined differences in nocturnal hypertension and non‐dipping systolic/diastolic blood pressure among black and white men and women who underwent 24‐hour ambulatory blood pressure monitoring at the Coronary Artery Risk Development in Young Adults study Year 30 Exam in 2015‐2016. Asleep and awake periods were determined from actigraphy complemented by sleep diaries. Nocturnal hypertension was defined as mean asleep systolic/diastolic blood pressure ≥ 120/70 mm Hg. Non‐dipping systolic and diastolic blood pressure, separately, were defined as a decline in awake‐to‐asleep blood pressure < 10%. Among 767 participants, the prevalence of nocturnal hypertension was 18.4% and 44.4% in white and black women, respectively, and 36.4% and 59.9% in white and black men, respectively. After multivariable adjustment and compared with white women, the prevalence ratio (95% confidence interval) for nocturnal hypertension was 1.65 (1.18‐2.32) for black women, 1.63 (1.14‐2.33) for white men, and 2.01 (1.43‐2.82) for black men. The prevalence of non‐dipping systolic blood pressure was 21.5% and 41.0% in white and black women, respectively, and 20.2% and 37.9% in white and black men, respectively. Compared with white women, the multivariable‐adjusted prevalence ratio (95% confidence interval) for non‐dipping systolic blood pressure was 1.66 (1.18‐2.32), 0.91 (0.58‐1.42) and 1.66 (1.15‐2.39) among black women, white men, and black men, respectively. Non‐dipping diastolic blood pressure did not differ by race‐sex groups following multivariable adjustment. In conclusion, black women and men have a high prevalence of nocturnal hypertension and non‐dipping systolic blood pressure.