Clinicopathological insights into lupus nephritis in South Africans: a study of 251 patients.

There are few published studies on biopsy proven lupus nephritis (LN) from sub-Sahara Africa, mainly due to lack of expertise and pathology back-up for performing and interpreting renal biopsies in many centres. The purpose of this study was to document factors associated with biopsy proven LN and to determine clinical and laboratory models that best predict proliferative LN in South Africans. Of the 251 patients studied, 84.1% were females and 79.3% were of mixed ancestry. There were more observed cases of proliferative LN (63%) than non-proliferative LN. Factors associated with proliferative LN were male gender (p = 0.049), haematuria on dipstix (p < 0.0001), proteinuria on dipstix (p = 0.042), low serum albumin (p = 0.032), low complement C3 (p < 0.0001), low complement C4 (p = 0.009) and positive double-stranded DNA (p = 0.039). Using four models designed from various combinations of the factors associated with proliferative LN, the specificity and positive predictive values were highest for the model that combined gender (male), presence of dipstix haematuria and proteinuria, hypoalbuminaemia, low C3 and low C4 and positive double-stranded DNA (100% respectively). Further study is recommended to identify the value of using these demographic and laboratory parameters in identifying patients with proliferative LN in resource limited centres where the performance of a biopsy is not possible.

COVID-19 complications in a small-town hospital in South Africa.

South Africa has experienced three deadly waves of the COVID-19 pandemic with devastating consequences, but little is known about the experiences in small-town hospitals in the country. Between May 2020 and June 2021, author GC treated ~100 confirmed COVID-19 cases. This retrospective case series report describes 10 of these cases, 7 with unusual complications and 3 with sudden death.

PASCAR commentary on the International Society of Hypertension global guidelines 2020: relevance to sub-Saharan Africa.

Hypertension guidelines have been based on country-specific data until the publication of the International Society of Hypertension (ISH) global guidelines. The major differences between the ISH global guidelines and other international guidelines are the stratified recommendations to accommodate differences in available resources between countries and within countries. This is a key and novel proposal in the new ISH guidelines. There is the separation of optimal versus essential criteria for diagnosis and treatment according to availability of resources. This guideline includes recommendations for sub-Saharan Africa. The Pan-African Society of Cardiology (PASCAR) continues to promote awareness and recommendations on hypertension in Africa. This commentary provides a summary and discussion of the global guidelines in order to clarify the position of PASCAR.

Hypertension in pregnancy: A future risk for chronic kidney disease in South Africa.

BACKGROUND: Hypertension in pregnancy is a risk factor for end-stage chronic kidney disease (ESKD) and is particularly common in South Africa (SA). There are no data for the risk of developing chronic kidney disease (CKD). OBJECTIVES: To conduct a study of all female patients who presented to the renal replacement programme at Groote Schuur Hospital, Cape Town, SA. METHODS: This was a retrospective study of female patients with ESKD who were presented to renal replacement meetings between 2007 and 2017. For each patient who was assessed, there was a comprehensive letter detailing patient demographics, as well as psychosocial and medical history, which served as the source data. Patients with a history of hypertension in pregnancy were identified as the case group and those without the condition were the control group. Patient demographics, causes of CKD, kidney function and outcome of the meeting were documented. RESULTS: Of the 415 female patients with ESKD, 70 (16.9%) had a history of hypertension in pregnancy. The ethnic breakdown was as follows: 132 (42.44%) black, 172 (55.3%) mixed ancestry and 7 (2.25%) white. Compared with the control group, the patients were younger, with a median age of 33 v. 41 years (p<0.001), higher serum creatinine 1 045 v. 751 µmol/L (p=0.017) and lower estimated glomerular filtration rate (eGFR) 4.0 v. 5.1 mL/min (p=0.029). Patients were more likely to abuse methamphetamine (5.7 v. 1.7%; p=0.049), and less likely to be diabetic (1.4 v. 20.9%; p<0.001) or HIV-positive (2.9 v. 12.5%; p=0.019). There were no ethnic differences between patients and controls. Underlying causes of renal disease showed significant differences, as patients were more likely to have hypertensive nephropathy (57.1 v. 22.9%; p<0.0001), and less likely to have diabetic kidney disease (1.4 v. 20.4%; p<0.001), HIV-associated nephropathy (HIVAN) (1.4 v. 6.4%) or polycystic kidney disease (1.4 v. 7.0%). There was no difference in acceptance to the dialysis and transplant programme (53 v. 47%). CONCLUSIONS: This study suggests an important link between hypertension in pregnancy and ESKD. The patients were significantly younger, presented later and were more likely to have hypertensive nephropathy. Methamphetamine abuse appears to be a risk factor. The study suggests that all women with hypertensive disorders during pregnancy need further evaluation and follow-up postpartum.

Registration of amiloride in South Africa: Cutting the Gordian knot.

Amiloride is an antagonist of the renal tubular epithelial sodium channel (ENaC). As such, it is a diuretic that is both potassium and magnesium sparing. It is used for the treatment of potassium depletion and hypertension, and is the specific therapy for hypertension due to overactivity of the ENaC (Liddle syndrome and several additional genetic causes of the Liddle phenotype - low renin and low aldosterone). It is listed as a World Health Organization essential drug, but has never been registered in South Africa (SA) and can therefore only be prescribed under a Section 21 application to the SA Health Products Regulatory Authority (SAHPRA) on a case-by-case basis. In SA, >50% of patients treated for hypertension are not controlled. In the USA, the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study reported that African Americans are more likely to be diagnosed with hypertension, more likely to be treated, more likely to be treated intensively, and less likely to achieve blood pressure (BP) control. Although the reasons are complex, studies show that 10 - 20% of blacks may carry the Liddle phenotype. Observational data and a controlled clinical trial done in three African countries have shown that these patients respond to amiloride and not to conventional guideline-based antihypertensive treatment. The former is likely to result in a significant reduction in cardiovascular, stroke and kidney morbidity and mortality, because of improved BP control. Amiloride is very unlikely to ever be registered in SA, as it was first developed >50 years ago, and SAHPRA regulations prevent widespread prescription of this essential drug. This is a classic Gordian knot that requires a novel approach from authorities to sever the knot and improve the health of many South Africans.

High prevalence of "non-dipping" blood pressure and vascular stiffness in HIV-infected South Africans on antiretrovirals.

BACKGROUND: HIV-infected individuals are at increased risk of tissue inflammation and accelerated vascular aging ('inflamm-aging'). Abnormal diurnal blood pressure (BP) rhythms such as non-dipping may contribute to an increased risk of cardiovascular and cerebrovascular events in HIV infected individuals. However, little data exists on ambulatory blood pressure (ABP) and measures of vascular stiffness in the black African HIV infected population. METHODS: This is a cross-sectional analysis of otherwise well, HIV infected outpatients on ART for >5 years. Study assessments included: 24hr ABP monitoring, pulse wave velocity (PWV) and central aortic systolic pressure (CASP) using a AtCor Medical Sphygmocor device, fasting lipogram, oral glucose tolerance test, high-sensitivity C-reactive protein (hsCRP) and anthropometric data. Patients completed a questionnaire of autonomic symptoms. CD4+ counts and viral loads were obtained from the National Laboratory results system. RESULTS: Sixty seven black participants were included in the analysis of whom 91% (n = 61) were female with a mean age of 42.2 ± 8.6 years. The median duration on ART was 7.5 years (IQR = 6-10), 84% were virally supressed and the median CD4 count was 529.5cells/mm3 (IQR = 372.0-686.5). The majority (67%) were classified as overweight and 76% had an increased waist circumference, yet only 88% of participants were normotensive. A hsCRP level in the high cardiovascular risk category was found in 68% of participants. The prevalence of non-dipping BP was 65%. Interestingly, there was no association on multivariable analysis between dipping status and traditional risk factors for non-dipping BP, such as: obesity, autonomic dysfunction and older age. CONCLUSION: This relatively young cross-sectional sample of predominantly normotensive, but overweight black women on effective ART >5 years showed: a high prevalence of non-dipping BP, inflammation and vascular stiffness. Causality cannot be inferred but cardiovascular risk reduction should be emphasized in these patients.

Therapeutic drug monitoring of amlodipine and the Z-FHL/HHL ratio: Adherence tools in patients referred for apparent treatment-resistant hypertension.

BACKGROUND: Non-adherence to antihypertensives is a cause of 'pseudo-treatment-resistant' hypertension. OBJECTIVE: To determine whether monitoring plasma amlodipine concentrations and inhibition of angiotensin-converting enzyme (ACE) can be adjunct adherence tools. METHODS: Patients with hypertension who were prescribed enalapril and amlodipine were enrolled. Blood pressures (BPs) were monitored and an adherence questionnaire was completed. Steady-state amlodipine was assayed using liquid chromatography-mass spectrometry and degree of ACE inhibition using the Z-FHL/HHL (z-phenylalanine-histidine-leucine/hippuryl-histidine-leucine) ratio. RESULTS: One hundred patients (mean (standard deviation) age 50.5 (12) years, 46% male) were enrolled. Based on plasma assays, 26/97 patients (26.8%) were unsuppressed by enalapril and 20/100 (20%) were sub-therapeutic for amlodipine. There were significant BP differences based on plasma levels of the medication: 21/20 mmHg lower in the group with suppressed ACE and 26/20 mmHg in the group with steady-state amlodipine concentrations. CONCLUSIONS: Monitoring antihypertensive adherence by assaying plasma medication concentrations is a feasible option for evaluating true v. pseudo-resistant hypertension.

Evaluation and management of patients referred to a tertiary-level hypertension clinic in Cape Town, South Africa.

BACKGROUND: Hypertension remains a global health burden, with a high incidence of long-term morbidity and mortality. OBJECTIVE: To evaluate blood pressure (BP) control, factors associated with poor BP control, target organ damage (TOD), white-coat hypertension, treatment-resistant hypertension and secondary hypertension in patients referred to a tertiary-level hypertension clinic. METHOD: This was a prospective case-control study of patients referred for specialist hypertension management. Patient parameters recorded included age, gender, body mass index, uric acid, cholesterol, screening BP, follow-up BP, TOD and medications. We also recorded causes of secondary hypertension. Net BP change and the percentage achieving target BP were calculated in all patients followed up. RESULTS: A total of 175 patients were sampled (72 males and 103 females, mean age 46.5 years). Of the patients 16.6% had a normal screening BP; 62.9% of patients were followed up, and 43.6% of these achieved BP control. After intervention, there was a net drop of 13.2 mmHg (range 7.9 - 18.4) in systolic BP and of 3.8 mmHg (4.4 - 12.0) in diastolic BP. Of all the patients, 12.6% had resistant hypertension, 49.1% had evidence of left ventricular hypertrophy and 18.3% had microalbuminuria; 13.1% of the patients were diagnosed with secondary hypertension. CONCLUSION: Specialist intervention was useful in identifying patients with white-coat and secondary hypertension, as well as in improving hypertension control in patients with apparent treatment-resistant hypertension. However, a significant percentage of patients did not reach target BP, and further efforts are required to identify the underlying causes for this.

Hypertension, end-stage renal disease and mesangiocapillary glomerulonephritis in methamphetamine users.

BACKGROUND: Methamphetamine abuse has risen dramatically in South Africa. The chronic effects of abuse on the kidneys and blood pressure have not been documented. This study reviewed patients referred for evaluation of kidney disease and/or hypertension, who had been abusing methamphetamines. METHODS: The records of patients referred to the renal unit between 2005 and 2013 who had been using methamphetamines were retrospectively reviewed. Patient demographics, biophysical parameters, blood pressure, renal function, renal ultrasound and biopsy findings, complications of chronic kidney disease and comorbidities were recorded. RESULTS: Forty-seven patients were included in the study. Their mean age was 29 years. Hypertension was present in 42 (89.4%) of patients, with malignant hypertension in 21 (44.7%). Forty-five (95.7%) had chronic kidney disease (CKD), and 26 (55.3%) had end-stage renal disease. Renal biopsies were performed in 24 patients. Twelve (50.0%) of the biopsies showed hypertensive changes and 14 (58.3%) mesangiocapillary glomerulonephritis type 1, with deposition of IgM and C3 complement. CONCLUSION: Methamphetamine use is associated with severe hypertension, mesangiocapillary glomerulonephritis and CKD.

Community-acquired bacteremia in the elderly: a prospective study of 121 cases.

OBJECTIVE: To describe community-acquired bacteremia in the elderly and correlate clinical and laboratory findings with outcome. DESIGN: Prospective study of consecutive cases. SETTING: Large community-based teaching hospital. PATIENTS: One hundred and twenty-one elderly patients aged 65 to 89 years, seen between February 1, 1986 and January 31, 1988. MAIN OUTCOME MEASURES: Bacteriological cultures, symptoms and signs, laboratory findings, and mortality. RESULTS: Gram-negative organisms accounted for 65 (54%) cases and Gram-positive organisms for 47 (39%) cases, while nine (7%) cases were polymicrobial. E. coli (39%), Klebsiella sp. (8%), S. pneumoniae (14%), and S. aureus (12%) were the most commonly isolated organisms. The overall mortality was 38%. A poor prognosis was associated with confusion as a presenting symptom (P < 0.0003), hypotension (P < 0.0003), and inappropriate or delayed treatment (P < 0.02). A good prognosis was associated with E. coli as the pathogen (P < 0.0003) and prompt, appropriate antibiotic therapy. CONCLUSION: Community-acquired bacteremia in the elderly has a high mortality rate. Early recognition and prompt, appropriate treatment are critical in reducing the mortality.

Community-acquired Staphylococcus aureus bacteraemia in patients who do not abuse intravenous drugs.

Despite advances in antimicrobial therapy and intensive care support, Staphylococcus aureus continues to cause significant morbidity and mortality. We studied community-acquired S. aureus bacteraemia in a population where intravenous drug abuse is extremely uncommon, prospectively reviewing all such patients (n = 113) admitted to Groote Schuur Hospital from February 1986 to January 1991. Overall mortality was 35%. Factors associated with poor outcome were: confusion on presentation, failure to mount a febrile response, acute renal failure, adult respiratory distress syndrome, shock, endocarditis, disseminated intravascular coagulation and platelet count of < 100 x 10(9)/l. Only confusion, acute renal failure and shock were independently associated with death by stepwise regression analysis. Skin infections were the most commonly identified source of bacteraemia (22%), but in 58% of patients the source was not determined. Twenty-six percent of patients were diabetic. Almost all patients (90%) developed one or more complications. In those who survived, therapy was generally prolonged, with a median of 70 days and range of 7-393 days, depending on the associated complications. Community-acquired S. aureus bacteraemia is a serious condition associated with a high complication rate and mortality.

Water intoxication: a possible complication during endurance exercise.

Four athletes developed water intoxication (hyponatremia) during endurance events lasting more than 7 h. The etiology of the condition appears to be voluntary hyperhydration with hypotonic solutions combined with moderate sweat sodium chloride losses. The reason why the fluid excess in these runners was not corrected by increased urinary losses is unknown. When advised to drink less during prolonged exercise, three of the athletes have subsequently completed prolonged endurance events uneventfully.

A prospective clinical trial comparing the treatment of idiopathic membranous nephropathy and nephrotic syndrome with simvastatin and diet, versus diet alone.

Of 17 patients with idiopathic membranous nephropathy (IMN) and nephrotic syndrome, 9 were allocated to treatment with simvastatin (an HMG CoA-reductase inhibitor) and low cholesterol diet, and 8 to diet alone. At entry, the treatment and control groups did not differ in mean serum creatinines, chromium-labelled EDTA clearances, urinary protein/creatinine ratios, serum albumins, and lipid profiles. The mean follow up period (+/- SEM) in the treated group was 19.3 (+/- 4.4) months compared with 16.6 (+/- 5.9) months in the control group. At the end of the trial the fall in chromium-labelled EDTA clearances was similar (-1.27 versus -1.28 mls/min/months/1.73 m2) in the treatment and control groups respectively. The mean (+/- SEM) total and LDL-cholesterol had gone from 10.5 (+/- 0.94) and 8.02 (+/- 1) mmol/l to 5.2 (+/- 0.49) and 3.47 (+/- 0.44) respectively in the treated patients. Additionally the mean (+/- SEM) albumin and urinary protein/creatinine ratio went from 25.6 (+/- 2.4) gm/l and 0.52 (+/- 0.09) gm/mmol to 45.5 (+/- 2.8) and 0.13 (+/- 0.04) respectively. There was little change in total and LDL-cholesterol; albumin and urinary protein/creatinine ratio in the control group. This study supports the observation that lowering serum cholesterol in the nephrotic syndrome reduces proteinuria and increases serum albumin levels. No difference in the rate of decline in renal function could be demonstrated.

Is preliminary binephrectomy necessary in patients with autosomal dominant polycystic kidney disease undergoing renal transplantation?

Patients with end-stage chronic renal failure due to autosomal dominant polycystic kidney disease who underwent renal transplantation with or without preliminary binephrectomy were retrospectively studied to determine the effect of binephrectomy on outcome. Nineteen patients were identified. Thirteen patients had no surgery prior to transplantation and six underwent preliminary binephrectomy. One patient died as a result of the nephrectomy. Twenty-one renal allografts were performed on 18 patients of whom seven have died of sepsis; 10 have functioning grafts and one has returned to dialysis. Patients not undergoing preliminary binephrectomy had a statistically significant (p less than 0.05) increase in mortality and morbidity due to septic complications related to polycystic kidney disease. Indications for bilateral nephrectomy should be reconsidered.

Continuous ambulatory peritoneal dialysis: an option in the developing world?

OBJECTIVE: To evaluate specified biomedical, socio-economic, and psychosocial criteria as predictors of therapeutic success to optimize patient selection for continuous ambulatory peritoneal dialysis (CAPD) in a developing country. DESIGN: A retrospective cohort study investigating the relationship between episodes of peritonitis and exitsite infection, and predetermined biomedical, socioeconomic, and psychosocial data. SETTING: A CAPD unit in a large tertiary care teaching hospital. PATIENTS: All 132 patients entering the CAPD program between 1987 and 1991. RESULTS: Overall mean survival time on CAPD was 17.3 months. Peritonitis rates were high, especially among blacks. Multivariate analysis demonstrated that increased peritonitis rates were associated with age, black race, diabetes, and strongly so with several psychosocial factors. Because being black was strongly linked to poor socioeconomic conditions, repeat analysis excluding blacks showed the same associations with the above variables, but, additionally, several socioeconomic factors were associated with high peritonitis rates. No significant explanatory variables were shown for exit-site infections. CONCLUSIONS: The association of biomedical, socioeconomic, and psychosocial variables with high peritonitis rates has important implications for the selection of patients for CAPD in this setting.

Hearing thresholds in CAPD patients.

Ultra high frequency (UHF, 10-20 kHz) and conventional audiometric thresholds (0,25-8 kHz) were obtained from 42 stable CAPD patients. Twenty-one (50%) and 11 (25%) of the patients had UHF and conventional hearing loss respectively, when compared to age related control data. This was unrelated to length of chronic renal failure and number of treatments with ototoxic drugs. Sixteen of these patients were monitored audiometrically using UHF during a course of vancomycin therapy for peritonitis. There was no significant change in hearing thresholds. In conclusion there is high incidence of hearing loss in CAPD patients which is unrelated to ototoxic drugs.

South African hypertension practice guideline 2014.

OUTCOMES: Extensive data from many randomised, controlled trials have shown the benefit of treating hypertension (HTN). The target blood pressure (BP) for antihypertensive management is systolic < 140 mmHg and diastolic < 90 mmHg, with minimal or no drug side effects. Lower targets are no longer recommended. The reduction of BP in the elderly should be achieved gradually over one month. Co-existent cardiovascular (CV) risk factors should also be controlled. BENEFITS: Reduction in risk of stroke, cardiac failure, chronic kidney disease and coronary artery disease. RECOMMENDATIONS: Correct BP measurement procedure is described. Evaluation of cardiovascular risk factors and recommendations for antihypertensive therapy are stipulated. Lifestyle modification and patient education are cornerstones of management. The major indications, precautions and contra-indications are listed for each antihypertensive drug recommended. Drug therapy for the patient with uncomplicated HTN is either mono- or combination therapy with a low-dose diuretic, calcium channel blocker (CCB) and an ACE inhibitor (ACEI) or angiotensin receptor blocker (ARB). Combination therapy should be considered ab initio if the BP is ≥ 160/100 mmHg. In black patients, either a diuretic and/or a CCB is recommended initially because the response rate is better compared to an ACEI. In resistant hypertension, add an alpha-blocker, spironolactone, vasodilator or ß-blocker. VALIDITY: The guideline was developed by the Southern African Hypertension Society 2014©.

South African hypertension guideline 2011.

OUTCOMES: Extensive data from randomised controlled trials have shown the benefit of treating hypertension. The target blood pressure (BP) for antihypertensive management is systolic <140 mmHg and diastolic <90 mmHg with minimal or no drug side-effects; however, stricter BP control is required for patients with end-organ damage, co-existing risk factors and co-morbidity, e.g. diabetes mellitus. The reduction of BP in the elderly and in those with severe hypertension should be achieved gradually over 1 month. Co-existent risk factors should also be controlled. BENEFITS: Benefits of management include reduced risks of stroke, cardiac failure, chronic kidney disease and coronary heart disease. RECOMMENDATIONS: The correct BP measurement procedure is described, and evaluation of cardiovascular risk factors and recommendations for antihypertensive therapy are stipulated. The total cardiovascular disease risk profile should be determined for all patients to inform management strategies. Lifestyle modification and patient education are cornerstones in the management of every patient. Major indications, precautions and contra-indications to each recommended antihypertensive drug are listed. Combination therapy should be considered ab initio if the BP is ≥ 20/10 mmHg. First-line drug therapy for uncomplicated hypertension includes low-dose thiazide-like diuretics, calcium channel blockers (CCBs) or angiotensin-converting enzyme inhibitors (ACE-Is) (or ARBs - angiotensin II receptor blockers). If the target BP is not obtained, a second antihypertensive should be added from the aforementioned list. If the target BP is still not met, the third remaining antihypertensive agent should be used. In black patients either thiazide-like diuretics or CCBs can be used initially, because response rates are better than with ACE-Is or ß-blockers. In treating resistant hypertension, a centrally acting drug, vasodilator, α-blocker, spironolactone or ß-locker should be added. This guideline includes management of specific situations, i.e. hypertensive emergency and urgency, severe hypertension with target organ damage, hypertension in diabetes mellitus, resistant hypertension, fixed drug combinations, new trials in hypertension, and interactions of antihypertensive agents with other drugs. VALIDITY: The guideline was developed by the Southern African Hypertension Society.

Achieving blood preSsure goals sTudy in uncontrolled hypeRtensive pAtients treated with a fixed-dose combination of ramipriL/hydrochlorothiazide: the ASTRAL study.

BACKGROUND: Hypertension is a common cardiovascular disease, affecting adults worldwide and it accounts for up to 30% of all deaths. The need for better control of arterial hypertension justifies observational studies designed to better understand the real-life management of hypertensive patients. The ASTRAL study was primarily designed to evaluate the percentage of hypertensive patients achieving blood pressure goals after eight weeks of treatment with a fixeddose combination of ramipril/hydrochlorothiazide (HCTZ). METHODS: The study was a multi-centre, non-comparative, Open-label, observational study conducted in 36 centres in five sub-Saharan African countries, namely Cameroon, Congo Brazzaville, Democratic Republic of Congo (DRC), Madagascar and Nigeria. Four hundred and forty-nine men and women 18 years of age or older with hypertension not controlled by an ACE inhibitor, a diuretic or any other monotherapy or anti-hypertensive combination not containing a diuretic in a fixed dose were considered eligible for inclusion in this eight-week study. The study consisted of three visits, visit one (V1) at baseline, visit two (V2) after four weeks and visit three (V3) after eight weeks. RESULTS: The mean age of the patients was 54.7 ± 11.7 years (20-90 years) and most were categorised by the WHO criteria as either overweight or obese (71.6%). After four and eight weeks of treatment with the study drug, systolic and diastolic blood pressures significantly changed from baseline: -24.7/-14.2 mmHg (p < 0.001) and -31.7/-17.9 mmHg (p < 0.001), respectively. There were 60.2% of the non-diabetics on prior monotherapy who, at eight weeks, fulfilled the primary blood pressure goal for SBP and DBP, versus 26.5% of the diabetic patients, also on monotherapy. Few adverse events were reported, with facial oedema and dry cough recurring twice in two patients. CONCLUSION: Fixed-dose combination of ramipril/HCTZ is therefore effective, tolerable and has a good safety profile for blood pressure control in black Africans.

The R563Q mutation of the epithelial sodium channel beta-subunit is associated with hypertension.

BACKGROUND: A high prevalence of the R563Q mutation of the epithelial sodium channel ß-subunit has been reported in South African hypertensives compared with unrelated normotensive controls. To delineate the effects of this mutation against a more uniform genetic background, this study investigated the association of the mutation with hypertension within affected kindreds. METHODS: Forty-five index patients and members of their kindreds were studied. Blood pressure, serum potassium and the presence of the R563Q mutation were determined. RESULTS: Of the 136 individuals studied, 89 were heterozygous for the R563Q mutation and 47 homozygous RR. The mean arterial pressure was significantly higher in the R563Q heterozygous group (p = 0.005) after adjusting for gender, race, age and kindred membership. Of the R563Q heterozygous subjects, 71 (80%) had hypertension, while 17 (36%) of the R563Q homozygous RR subjects were hypertensive. Six R563Q heterozygous subjects had hypokalaemia and one R563Q homozygous RR subject had hypokalaemia, but the difference was not statistically significant. Two heterozygous patients had Liddle's syndrome, both occurring during pregnancy. CONCLUSION: The R563Q mutation of ß-ENaC is associated with hypertension within affected kindreds, but does not usually cause the full Liddle's syndrome phenotype.