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Biomedical subjects

G C Curhan

Publications and source records attributed to G C Curhan.

33 records · Page 2Linked to original sources
PubMed1998

Nephrolithiasis and risk of hypertension in women.

Cross-sectional and prospective studies of men suggest a positive association between nephrolithiasis and hypertension. However, this association remains controversial in women. We conducted a prospective study of the relation between nephrolithiasis and the risk for hypertension in the Nurses' Health Study, a cohort of 89,376 women aged 34 to 59 years in 1980. Information on the history of nephrolithiasis, physician-diagnosed hypertension, and other relevant exposures was obtained by biennial mailed questionnaire. A history of nephrolithiasis before 1980 was reported by 2,558 women (2.9%), and a history of hypertension was reported by 11,883 women (13.3%). Among women without hypertension before 1980, 12,540 women reported a new diagnosis of hypertension between 1980 and 1992, during 711,039 person-years of follow-up. Compared with those without a history of nephrolithiasis, the age-adjusted relative risk (RR) for incident hypertension in women with such a history was 1.36 (95% confidence interval [CI], 1.20 to 1.43). After further adjustment for body mass index (BMI) and the intake of calcium, sodium, potassium, magnesium, caffeine, and alcohol, the RR was only slightly attenuated (RR=1.24; 95% CI, 1.13 to 1.37). In contrast, the occurrence of incident nephrolithiasis during follow-up was similar in women with hypertension at baseline compared with women without (adjusted odds ratio [OR]=1.01; 95% CI, 0.85 to 1.20). These data are consistent with the results obtained in men and support the hypothesis that a history of nephrolithiasis is associated with an increased risk for subsequent hypertension. Dietary factors, such as the intake of calcium, sodium, and potassium, do not explain this association. Unidentified pathogenic mechanisms common to nephrolithiasis and hypertension may be responsible for the development of both disorders.

Adult↗
PubMed1998

Nephrolithiasis and risk of hypertension.

A positive association between nephrolithiasis and blood pressure has been suggested in previous studies. However, controversy remains, due to methodological problems in some of the previous studies and absence of prospective data. We evaluated the relationship between nephrolithiasis and the risk of hypertension in a cohort of 51,529 men followed prospectively for 8 years. Information was obtained by biennial mailed questionnaires. At baseline in 1986, 4111 (8.0%) subjects reported a history of nephrolithiasis and 11,623 (22.6%) a diagnosis of hypertension. A positive association was found between the two disorders (age adjusted odds ratio [OR]: 1.31; 95% confidence interval [CI]: 1.30 to 1.32). Among men who reported both disorders, 79.5% reported that the occurrence of nephrolithiasis was prior to or concomitant with the diagnosis of hypertension. Among men without hypertension at baseline, the odds ratio for incident hypertension in men with a history of nephrolithiasis compared with those without was 1.29 (95% CI: 1.12 to 1.41; adjusted for age, body mass index, and intake of calcium, sodium, potassium, magnesium, and alcohol). The occurrence of incident nephrolithiasis during follow-up was similar in men with hypertension at baseline compared with that in men without (adjusted OR: 0.99, 95% CI: 0.82 to 1.21). These data support the hypothesis that prior occurrence of nephrolithiasis increases the risk of subsequent hypertension.

Adult↗
PubMed1998

Body size and risk of kidney stones.

A variety of factors influence the formation of calcium oxalate kidney stones, including gender, diet, and urinary excretion of calcium, oxalate, and uric acid. Several of these factors may be related to body size. Because men on average have a larger body size and a threefold higher lifetime risk of stone formation than women, body size may be an important risk factor for calcium oxalate stone formation. The association between body size (height, weight, and body mass index) and the risk of kidney stone formation was studied in two large cohorts: the Nurses' Health Study (NHS; n = 89,376 women) and the Health Professionals Follow-up Study (HPFS; n = 51,529 men). Information on body size, kidney stone formation, and other exposures of interest was obtained by mailed questionnaires. A total of 1078 incident cases of kidney stones in NHS during 14 yr of follow-up and a total of 956 cases in HPFS during 8 yr of follow-up were confirmed. In both cohorts, the prevalence of a stone disease history and the incidence of stone disease were directly associated with weight and body mass index. However, the magnitude of the associations was consistently greater among women. Specifically, the age-adjusted prevalence odds ratio for women with body mass index > or = 32 kg/m2 compared with 21 to 22.9 kg/m2 was 1.76 (95% confidence interval, 1.50 to 2.07), but 1.38 (95% confidence interval, 1.16 to 1.65) for the same comparison in men. For incident stone formation, the multivariate relative risks for the similar comparisons were 1.89 (1.51 to 2.36) for women and 1.19 (0.83 to 1.70) in men. Height was inversely associated with the prevalence of stone disease but was not associated with incident stone formation. These results suggest that body size is associated with the risk of stone formation and that the magnitude of risk varies by gender. Additional studies are necessary to determine whether a reduction in body weight decreases the risk of stone formation, particularly in women.

Adult↗
PubMed1997

Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones in women.

BACKGROUND: Calcium intake is believed to play an important role in the formation of kidney stones, but data on the risk factors for stone formation in women are limited. OBJECTIVE: To examine the association between intake of dietary and supplemental calcium and the risk for kidney stones in women. DESIGN: Prospective cohort study with 12-year follow-up. SETTING: Several U.S. states. PARTICIPANTS: 91,731 women participating in the Nurses' Health Study I who were 34 to 59 years of age in 1980 and had no history of kidney stones. MEASUREMENTS: Self-administered food-frequency questionnaires were used to assess diet in 1980, 1984, 1986, and 1990. The main outcome measure was incident symptomatic kidney stones. RESULTS: During 903,849 person-years of follow-up, 864 cases of kidney stones were documented. After adjustment for potential risk factors, intake of dietary calcium was inversely associated with risk for kidney stones and intake of supplemental calcium was positively associated with risk. The relative risk for stone formation in women in the highest quintile of dietary calcium intake compared with women in the lowest quintile was 0.65 (95% CI, 0.50 to 0.83). The relative risk in women who took supplemental calcium compared with women who did not was 1.20 (CI, 1.02 to 1.41). In 67% of women who took supplemental calcium, the calcium either was not consumed with a meal or was consumed with meals whose oxalate content was probably low. Other dietary factors showed the following relative risks among women in the highest quintile of intake compared with those in the lowest quintile: sucrose, 1.52 (CI, 1.18 to 1.96); sodium, 1.30 (CI, 1.05 to 1.62); fluid, 0.61 (CI, 0.48 to 0.78); and potassium, 0.65 (CI, 0.51 to 0.84). CONCLUSIONS: High intake of dietary calcium appears to decrease risk for symptomatic kidney stones, whereas intake of supplemental calcium may increase risk. Because dietary calcium reduces the absorption of oxalate, the apparently different effects caused by the type of calcium may be associated with the timing of calcium ingestion relative to the amount of oxalate consumed. However, other factors present in dairy products (the major source of dietary calcium) could be responsible for the decreased risk seen with dietary calcium.

Absorption↗
PubMed1997

Renal vasculitis with HIV seropositivity: potential manifestation of cytomegalovirus infection.

The associations among human immunodeficiency virus (HIV) infection, focal segmental glomerulosclerosis, and its variant, "collapsing glomerulopathy," often leading to chronic renal failure, are well described. HIV-seropositive patients may also develop a variety of immune complex-mediated glomerular diseases, including postinfectious glomerulonephritis, IgA nephropathy, and membranoproliferative glomerulonephritis. Herein we describe a case of pauci-immune necrotizing renal vasculitis in an HIV-seropositive patient, thereby expanding the differential diagnosis of acute renal failure in this setting.

Cytomegalovirus Infections↗
PubMed1997

Family history and risk of kidney stones.

Kidney stones develop more frequently in individuals with a family history of kidney stones than in those without a family history; however, little information is available regarding whether the increased risk is attributable to genetic factors, environmental exposures, or some combination. In this report, the relation between family history and risk of kidney stone formation was studied in a cohort of 37,999 male participants in the Health Professionals Follow-up Study. Information on family history, kidney stone formation, and other exposures of interest, including dietary intake, was obtained by mailed questionnaires. A family history of kidney stones was much more common in men with a personal history of stones at baseline in 1986 than in those without a history of stones (age-adjusted prevalence odds ratio, 3.16; 95% confidence interval [CI], 2.90 to 3.45). During 8 yr of follow-up, 795 incident cases of stones were documented. After adjusting for a variety of risk factors, the relative risk of incident stone formation in men with a positive family history, compared with those without, was 2.57 (95% CI, 2.19 to 3.02). Family history did not modify the inverse association between dietary calcium intake and the risk of stone formation. These results suggest that a family history of kidney stones substantially increases the risk of stone formation. In addition, these data suggest that dietary calcium restriction may increase the risk of stone formation, even among individuals with a family history of kidney stones.

Adult↗
PubMed1997

Dietary calcium, dietary protein, and kidney stone formation.

Kidney stone disease is common and is a major cause of morbidity involving the urinary tract. Rising incidence rates of calcium oxalate stone disease, the most common type of kidney stone, have focused attention on dietary habits and their potential role in the development of nephrolithiasis. Traditionally, calcium restriction had been recommended to reduce the likelihood of calcium stone formation, but recent evidence suggests that dietary calcium restriction may actually increase the risk. Observational and experimental data suggest that restriction of animal protein may lower the risk of stone formation, but a randomized trial did not confirm this finding. Dietary modification may play an important role in reducing the likelihood of stone recurrence. Notably, dietary calcium restriction should be avoided in patients who have had a calcium oxalate kidney stone.

Calcium, Dietary↗
PubMed1996

Birth weight and adult hypertension, diabetes mellitus, and obesity in US men.

BACKGROUND: Low birth weight has been associated with several chronic diseases in adults, including hypertension, diabetes mellitus, and obesity. Further study of these diseases in a large cohort with information on a wide variety of risk factors is essential to determine more precisely the risks associated with birth weight. METHODS AND RESULTS: We examined the relation between birth weight and cumulative incidence of adult hypertension, incidence of non-insulin-dependent diabetes mellitus, and prevalence of obesity in a cohort of 22,846 US men (Health Professionals Follow-up Study). Birth weights, medical histories, family histories, and other factors were collected by biennial mailed questionnaires. Logistic regression was used to examine the association between birth weight and these chronic adult diseases. Low birth weight was associated with an increased risk of hypertension and diabetes; high birth weight was associated with an increased risk of obesity. Compared with men in the referent birth weight category (7.0 to 8.4 lb), men who weighed < 5.5 lb had an age-adjusted odds ratio for hypertension of 1.26 (95% confidence interval [CI], 1.11 to 1.44) and for diabetes mellitus of 1.75 (95% CI, 1.21 to 2.54). There was no material change after controlling for adult body mass index and parental histories of hypertension and diabetes mellitus. Compared with men in the referent group, the age-adjusted odds ratio of being in the highest versus the lowest quintile of adult body mass index for men with birth weight > or = 10.0 lb was 2.08 (95% CI, 1.73 to 2.50). CONCLUSIONS: These findings support the hypothesis that early life exposures, for which birth weight is a marker, are associated with several chronic diseases in adulthood.

Adult↗
PubMed1996

Birth weight and adult hypertension and obesity in women.

BACKGROUND: Low birth weight has been associated with an increased risk of hypertension, and high birth weight has been associated with increased adult body mass index. Published studies on adults have included only a small number of women. METHODS AND RESULTS: We studied 71 100 women in the Nurses Health Study I (NHS I) who were 30 to 55 years of age in 1976 and 92 940 women in the Nurses' Health Study II (NHS II) who were 25 to 42 years of age in 1989. Information on birth weight, blood pressure, physician-diagnosed hypertension, and other relevant variables was collected by biennial mailed questionnaire. Ninety-five percent of the women were white. Compared with women in the middle category of birth weight (NHS I, 7.1 to 8.5 lb; NHS II, 7.0 to 8.4 lb), the age-adjusted odds ratio of hypertension in NHS I women with birth weights < 5.0 lb was 1.39 (95% CI, 1.29 to 1.50); in NHS II, for birth weights < 5.5 lb, the age-adjusted odds ratio was 1.43 (95% CI, 1.31 to 1.56). There was no material change in the estimates after adjustment for other risk factors. In addition, compared with women in NHS I who weighed 7.1 to 8.5 lb at birth, those who weighed > 10 lb had an age-adjusted odds ratio of 1.62 (95% CI, 1.38 to 1.90) of being in the highest (> 29.2 kg/m2) versus the lowest (< 21.9 kg/ m2) quintile of body mass index in midlife. Similar results were seen in the NHS II cohort. CONCLUSIONS: Early life exposures affecting birth weight may be important in the development of hypertension and obesity in adults.

Adult↗
PubMed1996

Prospective study of beverage use and the risk of kidney stones.

Patients with kidney stones are routinely advised to increase their fluid intake to decrease the risk of stone recurrence. However, there has been no detailed examination to determine whether the effect on recurrence varies by the type of beverage consumed. The authors conducted a prospective study of the relation between the intake of 21 different beverages and the risk of symptomatic kidney stones in a cohort of 45,289 men, 40-75 years of age, who had no history of kidney stones. Beverage use and other dietary information was measured by means of a semiquantitative food frequency questionnaire in 1986. During 6 years of follow-up (242,100 person-years), 753 incident cases of kidney stones were documented. After adjusting simultaneously for age, dietary intake of calcium, animal protein and potassium, thiazide use, geographic region, profession, and total fluid intake, consumption of specific beverages significantly added to the prediction of kidney stone risk (p < 0.001). After mutually adjusting for the intake of other beverages, the risk of stone formation decreased by the following amount for each 240-ml (8-oz) serving consumed daily: caffeinated coffee, 10% (95% confidence interval 4-15%); decaffeinated coffee, 10% (3-16%); tea, 14% (5-22%); beer, 21% (12-30%); and wine, 39% (10-58%). For each 240-ml serving consumed daily, the risk of stone formation increased by 35% (4-75%) for apple juice and 37% (1-85%) for grapefruit juice. The authors conclude that beverage type may have an effect on stone formation that involves more than additional fluid intake alone.

Adult↗
PubMed1996

A prospective study of the intake of vitamins C and B6, and the risk of kidney stones in men.

PURPOSE: The association between the intake of vitamins C and B6, and kidney stone formation was examined. MATERIALS AND METHODS: We conducted a prospective study of the relationship between the intake of vitamins C and B6 and the risk of symptomatic kidney stones in a cohort of 45,251 men 40 to 75 years old with no history of kidney calculi. Vitamin intake from foods and supplements was assessed using a semiquantitative food frequency questionnaire completed in 1986. RESULTS: During 6 years of followup 751 incident cases of kidney stones were documented. Neither vitamin C nor vitamin B6 intake was significantly associated with the risk of stone formation. For vitamin C the age-adjusted relative risk for men consuming 1,500 mg. daily or more compared to less than 250 mg. daily was 0.78 (95% confidence interval 0.54 to 1.11). For vitamin B6 the age-adjusted relative risk for men consuming 40 mg. daily or more compared to less than 3 mg. daily was 0.91 (95% confidence interval 0.64 to 1.31). After adjusting for other potential stone risk factors the relative risks did not change significantly. CONCLUSIONS: These data do not support an association between a high daily intake of vitamin C or vitamin B6 and the risk of stone formation, even when consumed in large doses.

Ascorbic Acid↗
PubMed1994

Regional variation in nephrolithiasis incidence and prevalence among United States men.

The southeastern region of the United States has long been considered to have higher rates of nephrolithiasis than other regions. Previous reports examined hospital discharge rates for nephrolithiasis rather than stone incidence rates and did not evaluate potential confounding variables. We studied prospectively the regional rates of incident stone formation within the United States in a cohort of 45,289 men 40 to 75 years old in 1986 who had no history of kidney stones. Dietary intake was measured by a semiquantitative food frequency questionnaire. During 6 years of followup 753 incident cases of kidney stones were documented. We also examined regional prevalence among 4,082 men who had a history of nephrolithiasis at the start of the study. There were no significant differences in age-adjusted incidence rates between the Southeast and other regions. Controlling for other risk factors, including age and relevant nutrients, did not alter the results. The prevalence of stone disease was significantly greater in the Southeast. Using the Southeast as the comparison region, a decreased risk of having a history of kidney stones was found, ranging from 13% (95% confidence interval 4 to 21%) lower in the Mid-Atlantic region to 31% (95% confidence interval 21 to 40%) lower in the Northwest. The prevalence in all other regions combined compared to the Southeast was also lower (odds ratio 0.82, 95% confidence interval 0.76 to 0.89). Therefore, individuals in the Southeast appear to have an overall greater risk of kidney stones. However, the magnitude of this effect is modest compared with previous estimates.

Adult↗
PubMed1994

Dietary factors and kidney stone formation.

Kidney stone disease is a substantial health problem associated with significant pain and suffering, as well as economic costs. Over $2 billion were spent in 1986 on stone disease, the majority on treatment of existing stones and only a small percentage on prevention. Clearly, efforts to prevent or at least reduce the likelihood of developing a kidney stone would be an important component of the care of patients at risk. In particular, modifiable dietary factors appear to play an important role in the formation of calcium oxalate stones--the type of stone formed in the vast majority of cases. Once secondary causes of stone formation, such as hyperparathyroidism and renal tubular acidosis, are excluded, dietary counselling is a prudent and effective element of the therapeutic regimen and kidney stone prevention program. Specifically, for individuals who have a history of a calcium-containing kidney stone, important dietary recommendations should include the following: Achieve adequate fluid intake to produce at least 2 liters of urine per day. Avoid calcium restriction (except in the rare instances of excessive intake of greater than several grams per day). It is recommended a dietary intake of elemental calcium of at least 800 mg/day (the current RDA for adults) to prevent a negative calcium balance, bone mineral loss, and increased intestinal absorption of oxalate. At present, there is no evidence to support the belief that calcium restriction is beneficial and current data suggest that it may in fact be harmful.(ABSTRACT TRUNCATED AT 250 WORDS)

Beverages↗
PubMed1993

A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones.

BACKGROUND: A high dietary calcium intake is strongly suspected of increasing the risk of kidney stones. However, a high intake of calcium can reduce the urinary excretion of oxalate, which is thought to lower the risk. The concept that a higher dietary calcium intake increases the risk of kidney stones therefore requires examination. METHODS: We conducted a prospective study of the relation between dietary calcium intake and the risk of symptomatic kidney stones in a cohort of 45,619 men, 40 to 75 years of age, who had no history of kidney stones. Dietary calcium was measured by means of a semiquantitative food-frequency questionnaire in 1986. During four years of follow-up, 505 cases of kidney stones were documented. RESULTS: After adjustment for age, dietary calcium intake was inversely associated with the risk of kidney stones; the relative risk of kidney stones for men in the highest as compared with the lowest quintile group for calcium intake was 0.56 (95 percent confidence interval, 0.43 to 0.73; P for trend, < 0.001). This reduction in risk decreased only slightly (relative risk, 0.66; 95 percent confidence interval, 0.49 to 0.90) after further adjustment for other potential risk factors, including alcohol consumption and dietary intake of animal protein, potassium, and fluid. Intake of animal protein was directly associated with the risk of stone formation (relative risk for men with the highest intake as compared with those with the lowest, 1.33; 95 percent confidence interval, 1.00 to 1.77); potassium intake (relative risk, 0.49; 95 percent confidence interval, 0.35 to 0.68) and fluid intake (relative risk, 0.71; 95 percent confidence interval, 0.52 to 0.97) were inversely related to the risk of kidney stones. CONCLUSIONS: A high dietary calcium intake decreases the risk of symptomatic kidney stones.

Adult↗