Incidence Of Nephrolithiasis Research Articles

188: Low Long Term Incidence of Nephrolithiasis in Patients with Ileal Bladder Substitutes

188: Low Long Term Incidence of Nephrolithiasis in Patients with Ileal Bladder Substitutes

Changing Gender Prevalence of Stone Disease

Recent studies suggest that the incidence of renal stone formation has been increasing and the male predominance of nephrolithiasis is decreasing, which may be due to changes in diet and lifestyle. We examined changes in the prevalence by gender of inpatient hospital discharges for urinary stone disease. The Nationwide Inpatient Sample was used for analysis. Discharges with an International Classification of Diseases, 9th revision, Clinical Modification principal diagnosis of 592.0 (calculus of kidney) or 592.1 (calculus of ureter) from 1997 to 2002 were included in the investigation. An estimated mean+/-SE 1,013,621+/-19,310 discharges for stone disease occurred from 1997 to 2002. Discharges for renal calculus increased by 18.9% during the study period (p<0.001), while discharges for ureteral calculus remained relatively constant. After adjusting for population changes discharges for renal calculi increased by 14.2% (p=0.002). In females discharges for renal calculi increased by 21.0% and discharges for ureteral calculi increased by 19.2% (each p<0.001). After adjusting for population changes renal calculus and ureteral calculus discharges in females increased by 22.0% (p=0.001) and 14.5% (p=0.005), respectively. In this nationally representative sample the population adjusted rate of discharges for stone disease in females dramatically increased from 1997 to 2002. This alteration represents a change in the prevalence by gender of treated stone disease from a 1.7:1 to 1.3:1 male-to-female ratio. It may reflect variations in the underlying prevalence by gender of stone disease. We speculate that the increasing incidence of nephrolithiasis might be due to lifestyle associated risk factors, such as obesity.

Analysis of Stone Disease in Morbidly Obese Patients Undergoing Gastric Bypass Surgery

Recent studies have demonstrated a higher incidence of nephrolithiasis in the morbidly obese. Nephrolithiasis also has been described as a potential outcome after gastric bypass surgery. This is the first study to our knowledge that examines the incidence of nephrolithiasis in the morbidly obese in the setting of gastric bypass surgery at a tertiary referral center. We retrospectively reviewed the records of patients undergoing laparoscopic gastric Roux-en-Y bypass surgery for morbid obesity at our institution for the incidence of nephrolithiasis preoperatively, de novo stones postoperatively, and both preoperative and postoperative stone formation. Of the 972 patients who underwent a laparoscopic gastric bypass for the treatment of morbid obesity between 1990 and the present, 85 (8.8%) were found to have upper urinary-tract calculi preoperatively, and 32 (3.2%) had de novo stones postoperatively. Of those 85 who had stones preoperatively, 26 (31.4%) developed recurrent stones postoperatively. These results support findings in the current literature that nephrolithiasis has a higher incidence in the morbidly obese population. The combination of preoperative stone history and gastric bypass surgery may place patients at a higher risk of future stone formation. This latter group of patients should be screened for postoperative stone formation.

Spondyloarthropathy: An Independent Risk Factor for Kidney Stones

To better stratify risk and to verify previous prevalence reports, we conducted a retrospective cohort study comparing the lifetime incidence of nephrolithiasis in patients with spondyloarthropathies (SpA) and rheumatoid arthritis (RA). Patients with SpA or rheumatoid factor-positive RA were identified from the rheumatology clinics of two Veterans Affairs hospitals and the University of Minnesota. Among them, 168 were confirmed to meet the American College of Rheumatology criteria and gave informed consent to participation. They were sent a survey regarding their rheumatologic diagnosis, coexistent conditions, medications, and history of kidney stones. Of the total, 143 patients responded and met the criteria for analysis. Rheumatoid arthritis patients were age and sex matched with SpA patients as controls. Populations were similar in all categories except that RA patients were more likely to have used prednisone (P < 0.001), bisphosphonates (P < 0.001), and calcium supplementation (P = 0.03). Kidney stones were reported by 23 (29.11%) of the 79 SpA patients compared with 8 (12.5%) of the 64 RA patients (chi (2) = 5.75; P = 0.025). Subgroup analysis of self-reporting stone history in 85 patients was found to be reliable on imaging review (sensitivity 82%; specificity 100%). Self-reporting of kidney stones by patients is a reliable measure. Despite adjusting for medication use and matching two similar arthritic populations, patients with SpA had a higher incidence of kidney stones than those with RA. This finding suggests that SpA is an independent risk factor for nephrolithiasis. Future studies will evaluate urinary risk factors and polymorphisms in the ANKH gene that may predispose to stone formation in this high-risk group.

Regionalization of Percutaneous Nephrolithotomy: Evidence for the Increasing Burden of Care on Tertiary Centers

The regionalization of procedures to specialized medical centers has been suggested as a means to improve the quality of care for select high risk procedures. Prior work has demonstrated the spontaneous regionalization of high risk procedures to tertiary centers. Similar concentration of complex, low risk procedures (e.g. percutaneous nephrolithotomy) to these centers would underscore the increasing burden of care placed on these hospitals. We used the Nationwide Inpatient Sample to identify 12,948 patients who underwent percutaneous nephrolithotomy for stones between 1988 and 2002. Regionalization was measured based on the 6 structural hospital qualities of teaching status, urban location, bed capacity, hospital throughput (all diagnoses), annual percutaneous nephrolithotomy volume and for-profit status. Logistic regression was used to determine the propensity of percutaneous nephrolithotomy to concentrate to these medical centers. Compared to procedures performed between 1988 and 1990, patients were more likely to undergo percutaneous nephrolithotomy at teaching (OR 1.6, 95% CI 1.3-1.9), high percutaneous nephrolithotomy volume (OR 1.7, 95% CI 1.6-1.9), large bed capacity (OR 1.2, 95% CI 1.1-1.3) and high throughput hospitals (OR 1.4, 95% CI 1.3-1.4) in the years 2000 to 2002. Percutaneous nephrolithotomy, a technically complex but low risk procedure, has spontaneously regionalized to tertiary centers, suggesting the migration of complex surgical care to these centers. The impact of this increasing burden of care on tertiary centers is unclear but may be problematic in the current reimbursement environment.

Renal stone epidemiology in Rochester, Minnesota: An update

Studies in Western countries have suggested an increasing incidence of nephrolithiasis (NL) in the latter part of the 20th century. Therefore, we updated NL epidemiology data for the Rochester population over the years 1970-2000. All Rochester residents with any diagnostic code that could be linked to NL in the years of 1970, 1980, 1990, and 2000 were identified, and the records reviewed to determine if they met the criteria for a symptomatic kidney stone as defined in a previous Rochester, MN study. Age-adjusted incidence (+/-s.e.) of new onset symptomatic stone disease for men was 155.1 (+/-28.5) and 105.0 (+/-16.8) per 100,000 per year in 1970 and 2000, respectively. For women, the corresponding rates were 43.2 (+/-14.0) and 68.4 (+/-12.3) per 100,000 per year, respectively. On average, rates for women increased by about 1.9% per year (P=0.064), whereas rates for men declined by 1.7% per year (P=0.019). The overall man to woman ratio decreased from 3.1 to 1.3 during the 30 years (P=0.006). Incident stone rates were highest for men aged 60-69 years, whereas for women, they plateaued after age 30. Therefore, since 1970 overall NL incidence rates in Rochester have remained relatively flat. However, NL rates for men have declined, whereas rates for women appear to be increasing. The reasons remain to be determined.

Les hypercalciuries

The frequency of hypercalciuria is increasing in western countries with an incidence of nephrolithiasis which can reach 13%. Hypercalciuria appears as an alteration of the calcium transport system (kidney, bowel, bone) which is regulated by calcitriol and parathormone. The aim of this review was to screen etiologies of hypercalciuria taking into account recent genetic advances (calcium epithelial channel and calcium sensing receptor). Hypercalciuria may be favored by nutritional causes (diet rich in calcium, sodium, carbohydrates, proteins, poor in phosphates and potassium). It may also be related to an increase in calcium absorption (vitamin D excess, primary hyperparathyroidism, sarcoidosis, lymphoma, estrogens, and certain genetic causes), an increase in osteoresorption (bone metastasis, myeloma, Paget, hyperthyroidism, immobilization, hypercortisolism and corticosteroid therapy), or a decrease of kidney tubular resorption (diuretics, Cacci and Ricci, acromegally, Bartter, familial dominant hypocalcemia, Fanconi, Dent, familial hypomagnesemia-hypercalciuria syndrome, type 1 distal tubular acidosis, pseudohypoaldosteronism, diabetes). If no cause is identified, persistence of hypercalciuria after instituting a correct diet is defined as idiopathic hypercalciuria. Treatment of the cause is essential in secondary hypercalciuria, in addition to diet (low sodium intake, normocalcic diet, hydration), associated with thiazide diuretics and biphosphonates if necessary.

Medical Treatment: Worthwhile and When?

The incidence of nephrolithiasis in industrialized countries is 0.5% to 1% annually. Stone formers subsequently face recurrence rates of 50% over 5 years. Annual costs in the United States for evaluation and treatment have been estimated at $1.83 billion USD [Clark JY, Thompson IM, Optenburg SA. Economic impact of urolithiasis in the United States. J Urol 1995;154:2020–2024]. Clearly the impact of urinary stone management poses an ever increasing medical, economic and social burden to modern society. The ability to detect 97% of underlying medical abnormalities in stone forming patients has stimulated discoveries of both selective and non-selective medical therapies to prevent stone recurrence. And yet there is no clear evidence in the literature that medical prophylaxis is cost effective. Various studies support the cost effectiveness of both proponents and adversaries of medical stone management. Nevertheless, there is clear evidence that medical therapy effectively prevents stone formation, especially when analyzing surrogate endpoints such as 24 urinary abnormalities, as well as primary endpoints such as stone formation. Therefore it makes intuitive sense to offer a search for underlying metabolic abnormalities in stone-forming patients and subsequently provide medical therapy, if the patient desires. Herein, we provide an overview in the medical evaluation and medical management of urinary stone disease.

Nephrolithiasis associated with ceftriaxone therapy: a prospective study in 51 children

Background: Background: Ceftriaxone, a third generation cephalosporin, is widely used for treating infection during childhood. The kidneys eliminate approximately 33–67% of this agent, and the remainder is eliminated via the...

METABOLIC RISK FACTORS FOR STONE FORMATION IN PATIENTS WITH CYSTIC FIBROSIS

Cystic fibrosis is characterized by chronic pulmonary disease, insufficient pancreatic and digestive function, and abnormal sweat concentrations. Patients with cystic fibrosis also have an increased incidence of nephrolithiasis. We compared the results of metabolic evaluation in patients with cystic fibrosis with and without nephrolithiasis. A total of 496 patients were evaluated at our center, including 98 with a mean age of 25 years who had cystic fibrosis and complete metabolic evaluation available between 1996 and 2000. Of these patients 13 (13%) had a history of nephrolithiasis. The records were reviewed for clinical characteristics and all patients underwent metabolic evaluation, including serum electrolyte measurement and 24-hour urine collection. Statistical analysis was done to compare the stone versus nonstone groups. The incidence of nephrolithiasis in our study was 3%. We identified 13 patients 16 to 41 years old (mean age 27) with nephrolithiasis, of whom 62% had had multiple episodes. Flank pain was the presenting symptom in 9 of the 13 cases (69%). Renal ultrasound and computerized tomography were the most common imaging modalities. In 9 cases stones were passed without intervention, extracorporeal shock wave lithotripsy was required in 2 and ureteroscopy with stone extraction was done in 2. Calcium oxalate was the dominant stone composition in the 9 patients in whom stone analysis was performed. Metabolic evaluation of the stone versus no stone groups showed elevated urinary oxalate (45.5 versus 42.5 mg./24 hours), relative calcium oxalate supersaturation (5.3 versus 7.2) and decreased urinary citrate in the 2 groups. There was a statistical difference in citrate excretion with lower levels in stone formers (102 versus 218 mg./24 hours, p = 0.0007). Patients with cystic fibrosis have an increased incidence of nephrolithiasis and are at high risk for recurrence. Metabolic evaluation is indicated in all patients with cystic fibrosis and urolithiasis since most have hyperoxaluria, urinary calcium oxalate supersaturation and decreased urinary citrate. Correcting detected stone risk factors in these cases may decrease stone recurrence.

Metabolic risk factors for stone formation in patients with cystic fibrosis.

Cystic fibrosis is characterized by chronic pulmonary disease, insufficient pancreatic and digestive function, and abnormal sweat concentrations. Patients with cystic fibrosis also have an increased incidence of nephrolithiasis. We compared the results of metabolic evaluation in patients with cystic fibrosis with and without nephrolithiasis. A total of 496 patients were evaluated at our center, including 98 with a mean age of 25 years who had cystic fibrosis and complete metabolic evaluation available between 1996 and 2000. Of these patients 13 (13%) had a history of nephrolithiasis. The records were reviewed for clinical characteristics and all patients underwent metabolic evaluation, including serum electrolyte measurement and 24-hour urine collection. Statistical analysis was done to compare the stone versus nonstone groups. The incidence of nephrolithiasis in our study was 3%. We identified 13 patients 16 to 41 years old (mean age 27) with nephrolithiasis, of whom 62% had had multiple episodes. Flank pain was the presenting symptom in 9 of the 13 cases (69%). Renal ultrasound and computerized tomography were the most common imaging modalities. In 9 cases stones were passed without intervention, extracorporeal shock wave lithotripsy was required in 2 and ureteroscopy with stone extraction was done in 2. Calcium oxalate was the dominant stone composition in the 9 patients in whom stone analysis was performed. Metabolic evaluation of the stone versus no stone groups showed elevated urinary oxalate (45.5 versus 42.5 mg./24 hours), relative calcium oxalate supersaturation (5.3 versus 7.2) and decreased urinary citrate in the 2 groups. There was a statistical difference in citrate excretion with lower levels in stone formers (102 versus 218 mg./24 hours, p = 0.0007). Patients with cystic fibrosis have an increased incidence of nephrolithiasis and are at high risk for recurrence. Metabolic evaluation is indicated in all patients with cystic fibrosis and urolithiasis since most have hyperoxaluria, urinary calcium oxalate supersaturation and decreased urinary citrate. Correcting detected stone risk factors in these cases may decrease stone recurrence.

Past history of nephrolithiasis and incidence of hypertension in men: a reappraisal based on the results of the Olivetti Prospective Heart Study.

We have previously reported that in the Olivetti Prospective Heart Study cohort the incidence of nephrolithiasis was higher in hypertensive participants than in normotensive ones. As the time sequence and the mechanisms underlying the association between nephrolithiasis and hypertension remain controversial, we further tested the hypothesis that in a cohort of normotensive males a history of nephrolithiasis predicts the development of future hypertension. The analysis was conducted in 381 male workers at Olivetti who were normotensive at the baseline examination and who were re-examined 8 years later. A past history of nephrolithiasis is associated with an increased risk of hypertension of 1.96 (95% CI=1.25-3.07) relative to subjects with a negative history, after adjusting for age. In this 8-year follow-up study, a history of nephrolithiasis resulted in an increased risk of developing hypertension in the future. As the reverse was also true, as previously reported, a clear-cut time sequence, as well as the mechanisms linking these two conditions, remain to be identified.

Principles and practice of HIV-protease inhibitor pharmacoenhancement.

Continually maintaining maximally suppressive drug concentrations represents a key defence against the emergence of resistance. If drug levels fall and replication occurs, the opportunity for mutant virus to be selected occurs. It has been increasingly recognized that variability in the pharmacokinetics of antiretrovirals, particularly protease inhibitors (PIs), means that drug exposure is not always optimal, giving the virus a chance to replicate. A significant number of patients receiving PIs two or three times daily will have trough (Ctrough or Cmin) plasma concentrations, which are close to, or below, the plasma protein binding-corrected inhibitory concentration (IC50 or IC95) during the dosing interval. It is primarily in this context that therapeutic drug monitoring of PIs has been proposed as an aid to patient management, to ensure that patients maintain adequate drug concentrations throughout the dosing interval. Ideally, an antiretroviral drug will have a pharmacokinetic (PK) profile that maintains drug levels well above the viral inhibitory concentration throughout the entire dosing interval. Beneficial drug-drug interactions have been shown to improve PI pharmacokinetics. Ritonavir (RTV) inhibits the key enzymes that limit the bioavailability or speed the metabolism of other PIs. It is therefore increasingly used for boosting and maintaining PI plasma concentrations. At low (100 mg twice a day) doses it acts as a pharmacoenhancer of indinavir (IDV), amprenavir, saquinavir, lopinavir and to a more limited degree nelfinavir. Using a pharmacoenhancer with a PI results in increased exposure to the PI, higher Cmin levels, and in most cases prolonged elimination half-lives. The long-term clinical benefits of PK enhancing are unknown as are the long-term toxicities, although the incidence of nephrolithiasis with IDV appears increased when IDV is combined with low-dose RTV in HIV-infected patients. Head-to-head clinical comparisons of boosted PI regimens will help answer some of the questions that remain with regard to PK enhancement.

Ureteropelvic junction obstruction and coexisting renal calculi in children: role of metabolic abnormalities

Objectives. To identify the role of metabolic risk factors in the development of renal calculi associated with ureteropelvic junction obstruction (UPJO) in children. Methods. A metabolic evaluation, including serum biochemistry and measurement of daily urinary calcium, creatinine, oxalate, citrate, magnesium, urate, and inorganic phosphorus, was carried out in three different populations as follows: UPJO group, 12 children with UPJO and coexisting nephrolithiasis (median age 6 years); calcium stone formation (CSF) group, 90 children with normal urologic anatomy and calcium urolithiasis (median age 7 years); control group, 24 healthy children (median age 7.3 years). The investigation data of the three groups were compared. Results. The stone composition was calcium oxalate in 9 of the 12 children with UPJO. The investigation data of the UPJO group and CSF group were not significantly different. Both groups differed from the control group in a similar manner. The UPJO and CSF groups excreted more oxalate ( P = 0.067 and 0.014, respectively) and less citrate ( P = 0.020 and 0.010, respectively) than did the control subjects. Conclusions. Abnormal urinary biochemistry seems to have an additional role in the high incidence of nephrolithiasis in children with upper tract anatomic anomalies, and the urinary biochemistry should be screened in such children.

Increased Incidence of Indinavir Nephrolithiasis in Patients with Hepatitis B or C Virus Infection

A HIV-1 patient database was scanned in March 1998, and 750 patients were identified who had received HAART including indinavir. Of these, 28 cases had nephrolithiasis; and 85 asymptomatic indinavir-treated patients were randomly selected as controls. The characteristics of cases and controls were compared by analysis of variance for quantitative parameters and by Fisher's exact test for classes. We observed a significant increase in the incidence of nephrolithiasis in patients co-infected with HIV-1 and either hepatitis C virus (HCV) (HCV RNA-positive) or hepatitis B virus (HBV) (HBs antigen-positive) (odds ratio and 95% confidence intervals: 2.8 and 1.1-7.7), whereas no significant differences were demonstrated between cases and controls with regard to age (42.4 +/- 8.0 versus 39.8 +/- 9.8 years), sex (male patients 70.4 versus 74.1%), duration of HIV-1 infection (8.6 +/- 3.1 versus 7.7 +/- 4.0 years), duration of indinavir treatment (16.1 +/- 5.8 versus 14.1 +/- 5.4 months), AST increase > or = 1.25 of normal (29.6 versus 25.9%), or ALT increase > or = 1.25 of normal (33.3 versus 22.4%). In co-infected patients, ALT increase (> or = 1.25 of normal), but not AST increase, at the time of indinavir initiation was statistically related to the occurrence of nephrolithiasis. We found a significant increase of nephrolithiasis incidence in patients co-infected with HIV-1 and HCV or HBV, which suggests that underlying multifactorial hepatic damage may limit liver catabolism of indinavir, and consequently increase its renal excretion and the risk of nephrolithiasis. Caution is therefore advised when initiating indinavir treatment in HIV patients with evidence of HBV or HCV infection.

Incidence of urolithiasis in cystectomy patients after intestinal conduit or continent urinary diversion.

The purpose of this study was to determine the incidence of nephrolithiasis in radical cystectomy patients treated with either intestinal conduit or continent urinary diversion. The charts from 94 patients who had undergone radical cystectomy with urinary diversion at our institution from 1988 to 1998 were reviewed retrospectively for this study. Charts and radiographs from all patients were examined for renal function and evidence or urinary tract calculi. Two groups were compared: group I patients had undergone diversion with an intestinal conduit, and group II patients had received a continent diversion (primarily involving an Indiana pouch). Conduit diversions were typically done with a freely refluxing anastomosis (Bricker), whereas continent diversions were done with a nonrefluxing ureteral-intestinal anastomosis. Group I consisted of 54 patients who had undergone ileal conduit (50) or colon conduit (4) diversion with a mean follow-up of 2.5 years (range 0.6-7.0 years). Group II consisted of 40 patients who had undergone continent diversion (33 Indiana pouches, 7 orthotopic diversions) with a mean follow-up of 3.1 years (range 0.5-10.5 years). Laboratory studies of serum blood urea nitrogen, creatinine, and CO(2) were similar between the two groups. Six patients in group I developed urolithiasis, all in the upper tract. Stones developed at a mean of 3.1 years after urinary diversion. Three patients required operative intervention, whereas the others were managed expectantly. One patient in group II had an upper tract stone at the time of presentation for his bladder cancer, but no patient developed new upper tract stones during the present study period. Two patients in group II developed pouch calculi at a mean of 5 years after diversion; both required surgical intervention. In our study the risk for upper tract urolithiasis seemed higher in the intestinal conduit group (group I), with 11% of the patients developing stones. In the continent diversion group, no patient developed upper tract stones, although two patients (5%) developed pouch stones. Refluxing urine may contribute to an increased risk for stone formation after urinary diversion, whereas pouch stasis may contribute to stone formation in the continent diversion group.

The incidence of nephrolithiasis in patients with spinal neural tube defects.

Bladder stones are common in patients with spinal neural tube defects but there are little data on the incidence of renal calculi in this population. We examined the incidence, nature and risk factors of nephrolithiasis in our clinic population of patients with neural tube defects. We retrospectively reviewed the charts and radiological studies of 327 patients followed at our neural tube defects clinic with routine radiological imaging of the urinary tract. Additional confirmatory studies were performed when stones were noted. Renal calculi were identified in 20 patients with neural tube defects (6.1%). The incidence of nephrolithiasis increased with age. Renal stones were noted in 19 patients (10.7%) 12 years old or older. Management of the stones in these patients resulted in overall 53% stone-free and 87% recurrence rates after intervention. Major risk factors for new and/or recurrent renal stone formation were bacteriuria in 95% of the cases, lower urinary tract reconstruction in 80%, pelvicalicectasis in 70%, vesicoureteral reflux in 65%, a thoracic level spinal defect in 60% and renal scarring in 55%. These data suggest that there is a higher incidence of nephrolithiasis in patients with neural tube defects than in the general population and the risk of stone recurrence is also elevated. Most patients with stones had undergone lower urinary tract reconstruction. Other risk factors were bacteriuria, pelvicalicectasis, vesicoureteral reflux and a thoracic level neural tube defect.

THE INCIDENCE OF NEPHROLITHIASIS IN PATIENTS WITH SPINAL NEURAL TUBE DEFECTS

Purpose Bladder stones are common in patients with spinal neural tube defects but there are little data on the incidence of renal calculi in this population. We examined the incidence, nature and risk factors of nephrolithiasis in our clinic population of patients with neural tube defects. Materials and Methods We retrospectively reviewed the charts and radiological studies of 327 patients followed at our neural tube defects clinic with routine radiological imaging of the urinary tract. Additional confirmatory studies were performed when stones were noted. Results Renal calculi were identified in 20 patients with neural tube defects (6.1%). The incidence of nephrolithiasis increased with age. Renal stones were noted in 19 patients (10.7%) 12 years old or older. Management of the stones in these patients resulted in overall 53% stone-free and 87% recurrence rates after intervention. Major risk factors for new and/or recurrent renal stone formation were bacteriuria in 95% of the cases, lower urinary tract reconstruction in 80%, pelvicalicectasis in 70%, vesicoureteral reflux in 65%, a thoracic level spinal defect in 60% and renal scarring in 55%. Conclusions These data suggest that there is a higher incidence of nephrolithiasis in patients with neural tube defects than in the general population and the risk of stone recurrence is also elevated. Most patients with stones had undergone lower urinary tract reconstruction. Other risk factors were bacteriuria, pelvicalicectasis, vesicoureteral reflux and a thoracic level neural tube defect.

Influence of environmental temperature on incidence of indinavir-related nephrolithiasis.

We analyzed the influence of temperature, humidity, and atmospheric pressure on the 1-year incidence of nephrolithiasis among human immunodeficiency virus type 1-infected patients treated with indinavir. One hundred three patients (13.6%) developed 326 episodes of nephrolithiasis. Eighty-two patients (79.6%) had more than one episode (range, two to seven episodes). The overall incidence ranged from 0 to 10.2 episodes per 100 patients exposed per month. There was a significant correlation between temperature and the overall incidence of nephrolithiasis and the incidence of recurrences but not with the incidence of first episodes. Nephrolithiasis was not related to humidity or atmospheric pressure. Our data support the standard recommendation of drinking at least 1.5 L of water daily to prevent nephrolithiasis in most patients treated with indinavir irrespective of meteorologic factors. However, the risk of nephrolithiasis is higher for a certain subgroup of patients when the environment is hot irrespective of adequate water intake.

Is familial hyperparathyroidism a unique disease?

Background. Familial hyperparathyroidism is a rare condition reported to behave more aggressively than sporadic hyperparathyroidism. Methods. A retrospective (1975 to 1995) analysis was performed on 30 such patients. All patients had at least one first-degree relative with surgically treated hyperparathyroidism and no personal or family history of multiple endocrine neoplasia. Results. There were 19 women and 11 men with a mean age of 39 years (range, 13 to 78 years). Fourteen patients (47%) had nephrolithiasis. The mean serum calcium level was 11.6 mg/dl (range, 10.5 to 15.3 mg/dl). Twenty-three primary and 15 repeat explorations (eight recurrent and seven persistent disease) were performed during the study period. Follow-up was obtained on all patients and ranged from 1 to 21 years (mean, 12 years). At the conclusion of the study, hypercalcemia (five recurrent and one persistent) was present in six patients (20%). Conclusions. Familial hyperparathyroidism is a distinct and unique entity. Patients are diagnosed at a young age and have a high incidence of nephrolithiasis. Long-term follow-up is mandatory because of the high incidence of both recurrent and persistent hyperparathyroidism. Surgical treatment should include subtotal parathyroidectomy and routine transcervical thymectomy performed in centers with experience in the management of multiple-gland parathyroid disease.