Calcium nephrolithiasis and medullary sponge kidney in women

Sex Differences and the Risk of Kidney Stones

A significant increase in the prevalence of kidney stones has been observed worldwide. In the past decades, this expansion was more pronounced among women than men. The precise mechanisms involved in the differences in the risk profile of stone disease between men and women have not been fully elucidated. Diet and lifestyle only partially can explain the differences, and the combination of factors such as the influence of sex hormones, genetics, and disorders in acid-base handling and urine pH, as well as differences in calcium tubular reabsorption and stone composition in men and women, may contribute to differences in the risk profile. In this review, we summarize the sex differences in the pathophysiologic basis of kidney stones, which may contribute to a more focused approach.

Large database study of urinary stone composition in South Korea: Korean Society of Endourology and Robotics (KSER) research series

Purpose

To evaluate the characteristics of urinary stone composition in a Korean population using a large database of stone composition.

Materials and Methods

From January 1, 2014, to June 30, 2019, a total of 33,078 urinary stone composition data were analyzed. Stone composition was classified into four main groups: calcium oxalate (CaOx), struvite, uric acid (UA), and calcium phosphate (CaP). We examined the relationship between stone composition and sex, age, geographic region, calendar month, and season.

Results

The CaOx group (46.41%) was the largest, followed by the struvite group (29.66%), UA group (19.61%), and CaP group (4.32%). The CaOx group tended to decrease with age, but the UA group increased with age. Also, the CaOx group had the highest percentage in summer and the lowest in spring (p<0.001). The struvite and CaP groups had higher percentages of females than males (struvite: 36.6% vs. 25.7%, p<0.001; CaP: 6.2% vs. 3.3%, p<0.001). Conversely, the UA stones were more common in males than in females (24.5% vs. 11.0%, p<0.001). The UA group had the lowest percentage in the capital region (p<0.001). The total male-to-female ratio decreased over time from 1.95:1 in 2014 to 1.67:1 in 2018 (p<0.001).

Conclusions

There were differences for each stone composition in the percentages according to sex, age, geographic region, month, and season. Identifying these differences based on the stone composition is vital for the treatment and prevention of urinary stones.

Ambiguous clear cell carcinoma in medullary sponge kidney: A case report

Medullary sponge kidney (MSK) is a characteristic renal malformation, with a relatively low incidence. Radiologically, identification of MSK is sometimes ambiguous when compared to a renal mass. Here, we report a novel renal clear cell carcinoma in MSK, and discuss our approach to treatment. We recommended that a preoperative biopsy should be performed, followed by a comprehensive discussion regarding the appropriate perioperative preparations and careful surgical techniques that should be performed for this complex disease.

Multivariate Analyses of Urinary Calculi Composition: A 13-Year Single-Center Study

BACKGROUND

The incidence and prevalence of urinary stone are increasing throughout the world. Compared to the past, recent demographics of patient with urolithiasis compositions are strikingly different. Furthermore, recent clinical studies implied that seasonal cyclicity might influence the distribution of stone composition.

METHODS

We sought to determine the trends in pathogenesis of urolithiasis based on urinary stone analyses. Between 2002 and 2014, a total of 2,383 eligible urinary stone samples from different patients were collected in our center. Infrared spectroscopy was used for urinary calculi analysis. A logistic regression analysis was used to investigate the relationship between urinary calculi composition and calendar month (season), gender, and age in north China during the past 13 years.

RESULTS

Calcium-containing calculi were the most frequent with an overall incidence of 84.1%. Calcium phosphate (CaP) or magnesium ammonium phosphate (MAP) stones were more frequent in females, while monohydrate calcium oxalate (COM), dihydrate calcium oxalate (COD), or uric acid (UA) stones were more common in males. Older individuals were associated with an increased risk of UA stones and a decreased risk of COD, CaP, or cystine stones. Additionally, from 2002 to 2014, the frequency of COD and MAP stone increased, whereas the trend of CaP, UA and cystine stones decreased. However, calendar month (season) was not significantly associated with differences in composition.

CONCLUSION

This study provides the present distribution of urolithiasis compositions in China. From 2002 to 2014, age and gender were significantly associated with stone composition, whereas calendar month was not.

Biopsy proven medullary sponge kidney: clinical findings, histopathology, and role of osteogenesis in stone and plaque formation

Medullary sponge kidney (MSK) is associated with recurrent stone formation, but the clinical phenotype is unclear because patients with other disorders may be incorrectly labeled MSK. We studied 12 patients with histologic findings pathognomonic of MSK. All patients had an endoscopically recognizable pattern of papillary malformation, which may be segmental or diffuse. Affected papillae are enlarged and billowy, due to markedly enlarged inner medullary collecting ducts (IMCD), which contain small, mobile ductal stones. Patients had frequent dilation of Bellini ducts, with occasional mineral plugs. Stones may form over white (Randall's) plaque, but most renal pelvic stones are not attached, and have a similar morphology as ductal stones, which are a mixture of calcium oxalate and apatite. Patients had no abnormalities of urinary acidification or acid excretion; the most frequent metabolic abnormality was idiopathic hypercalciuria. Although both Runx2 and Osterix are expressed in papillae of MSK patients, no mineral deposition was seen at the sites of gene expression, arguing against a role of these genes in this process. Similar studies in idiopathic calcium stone formers showed no expression of these genes at sites of Randall's plaque. The most likely mechanism for stone formation in MSK appears to be crystallization due to urinary stasis in dilated IMCD with subsequent passage of ductal stones into the renal pelvis where they may serve as nuclei for stone formation.

Stone composition as a function of age and sex

BACKGROUND AND OBJECTIVES

Kidney stones are heterogeneous but often grouped together. The potential effects of patient demographics and calendar month (season) on stone composition are not widely appreciated.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The first stone submitted by patients for analysis to the Mayo Clinic Metals Laboratory during 2010 was studied (n=43,545). Stones were classified in the following order: any struvite, any cystine, any uric acid, any brushite, majority (≥50%) calcium oxalate, or majority (≥50%) hydroxyapatite.

RESULTS

Calcium oxalate (67%) was the most common followed by hydroxyapatite (16%), uric acid (8%), struvite (3%), brushite (0.9%), and cystine (0.35%). Men accounted for more stone submissions (58%) than women. However, women submitted more stones than men between the ages of 10-19 (63%) and 20-29 (62%) years. Women submitted the majority of hydroxyapatite (65%) and struvite (65%) stones, whereas men submitted the majority of calcium oxalate (64%) and uric acid (72%) stones (P<0.001). Although calcium oxalate stones were the most common type of stone overall, hydroxyapatite stones were the second most common before age 55 years, whereas uric acid stones were the second most common after age 55 years. More calcium oxalate and uric acid stones were submitted in the summer months (July and August; P<0.001), whereas the season did not influence other stone types.

CONCLUSIONS

It is well known that calcium oxalate stones are the most common stone type. However, age and sex have a marked influence on the type of stone formed. The higher number of stones submitted by women compared with men between the ages of 10 and 29 years old and the change in composition among the elderly favoring uric acid have not been widely appreciated. These data also suggest increases in stone risk during the summer, although this is restricted to calcium oxalate and uric acid stones.

Environmental and stressful factors affecting the occurrence of kidney stones and the kidney colic

The first renal disease described from Hippocrates is nephrolithiasis with renal colic, which is the pain of stone passage and is also a common renal problem with easily recognizable characteristics. There has been much written about dietary factors, which have unequivocally been proved to play an important role in the formation of kidney stones. In this regard, it is of interest that the contribution of factors such as stressful events, life style, or occupation in the formation of kidney stones has not been well studied. This review examines the clinical evidence of the stressful events and other environmental factors affecting the occurrence of kidney stones.

CT urography for the diagnosis of medullary sponge kidney

BACKGROUND

Medullary sponge kidney (MSK) is characterized by malformation of the terminal collecting ducts and is associated with an increased risk of nephrolithiasis, nephrocalcinosis, urinary tract infections, renal acidification defects, and reduced bone density. It has been historically diagnosed with intravenous pyelography (IVP), which is falling out of favor as an imaging modality. CT urography (CTU) performed with multidetector CT (MDCT) has been shown to create images of the renal collecting system with similar detail as IVP; however, its utility in diagnosing MSK has not been defined.

CASE REPORT

We present the first 15 patients with recurrent symptomatic nephrolithiasis who were evaluated in our renal stone clinic with CTU. Four patients were diagnosed with MSK after visualization of the characteristic radiologic findings.

DISCUSSION

CTU effectively demonstrates the characteristic radiologic findings of MSK including collecting tubule dilatation, medullary nephrocalcinosis, nephrolithiasis, and medullary cysts. Dose reduction protocols can reduce radiation exposure below that associated with conventional IVP. We propose CTU be considered for the diagnosis of MSK.

Kidney stones: an update on current pharmacological management and future directions

INTRODUCTION

Kidney stones are a common problem worldwide with substantial morbidities and economic costs. Medical therapy reduces stone recurrence significantly. Much progress has been made in the last several decades in improving therapy of stone disease.

AREAS COVERED

This review discusses i) the effect of medical expulsive therapy on spontaneous stone passage, ii) pharmacotherapy in the prevention of stone recurrence and iii) future directions in the treatment of kidney stone disease.

EXPERT OPINION

Fluid intake to promote urine volume of at least 2.5 L each day is essential to prevent stone formation. Dietary recommendations should be adjusted based on individual metabolic abnormalities. Properly dosed thiazide treatment is the standard therapy for calcium stone formers with idiopathic hypercalciuria. Potassium alkali therapy is considered for hypocitraturia, but caution should be taken to prevent potential risk of calcium phosphate stone formation. For absorptive hyperoxaluria, low oxalate diet and increased dietary calcium intake are recommended. Pyridoxine has been shown effective in some cases of primary hyperoxaluria type I. Allopurinol is used in calcium oxalate stone formers with hyperuricosuria. Treatment of cystine stones remains challenging. Tiopronin can be used if urinary alkalinization and adequate fluid intake are insufficient. For struvite stones, complete surgical removal coupled with appropriate antibiotic therapy is necessary.

Clinical characteristics of potential kidney donors with asymptomatic kidney stones

BACKGROUND

Patients with symptomatic kidney stones are characterized by older age, male gender, white race, hypertension, obesity, metabolic syndrome and chronic kidney disease. Whether these characteristics differ in patients with asymptomatic kidney stones is unknown.

METHODS

All potential kidney donors who underwent protocol computed tomography angiograms/urograms (2000-08) at the Mayo Clinic were identified. Renal abnormalities, including kidney stones, were assessed radiographically. Comorbidities, including past symptomatic kidney stones, were abstracted from the medical record. Characteristics of persons with and without radiographic stones were compared. Stone burden among persons with and without past symptomatic stones was compared.

RESULTS

Among 1957 potential kidney donors, 3% had past symptomatic stones and 11% had radiographic stones (10% had only asymptomatic radiographic stones). Asymptomatic stone formers were more likely to be of white race, have low urine volumes and have radiographic findings of renal parenchymal thinning, focal renal scarring, medullary sponge kidney and polycystic kidney disease. Asymptomatic stone formers were not characterized by older age, male gender, hypertension, obesity, metabolic syndrome, abnormal kidney function, hyperuricemia, hypercalcemia or hypophosphatemia. Among persons with radiographic stones, those with past symptomatic stones had a slightly higher number of stones (mean 2.7 versus 2.4; P = 0.04), but a much greater diameter for the largest stone (mean 4.8 versus 1.6 mm; P < 0.001).

CONCLUSIONS

Asymptomatic kidney stone formers have different demographic characteristics and many lack the comorbidities that have been described in persons with symptomatic kidney stones. These findings suggest that different pathophysiologic mechanisms could be involved in asymptomatic stone formation versus symptomatic stone passage.

Medullary sponge kidney: causes and treatments

Medullary sponge kidney is a little known and little understood disease. A patient with a medullary sponge kidney may undergo decades of suffering in the form of infections and pain before any diagnosis is even made. When a diagnosis is made, it is more than likely to be an incidental finding from a test for another problem. However, on diagnosis there are a number of options available to treat this condition. These include non-invasive treatments such as drug therapy, diet or extracorporeal shock wave lithotripsy, to invasive therapies such as percutaneous nephrolithotomy, ureteroscopy and more advanced surgery. The aim of this article is to highlight this little known condition, outline the effects, and discuss the treatment options available to patients.

A review of the natural progression of medullary sponge kidney and a novel grading system based on intravenous urography findings

PURPOSE

Medullary sponge kidney (MSK) is a developmental abnormality of the medullary pyramids of the kidney, characterised by cystic dilatations of the collecting ducts. We investigated a cohort of patients with MSK to gain further information about its presentation, clinical course and treatment required. We devised a grading system based upon findings at diagnostic intravenous urography (IVU) and established a relationship between severity of IVU findings and severity of disease.

MATERIALS AND METHODS

The clinical notes and imaging of 29 patients with MSK were analysed. The severity of IVU findings was classified as follows: grade 1 (one calyx, unilateral), grade 2 (one calyx, bilateral), grade 3 (more than one calyx, unilateral) and grade 4 (more than one calyx, bilateral).

RESULTS

The age range at diagnosis was 12-69 (mean 39), mean follow-up period was 12.7 years. Increasing grade of IVU findings correlated with more frequent symptomatic stone episodes (grade 1: 0.09 episodes per patient per year; grade 4: 0.34). Higher grade was also related to the number of hospital admissions (grade 1: 0.182 per patient per year; grade 4: 0.282) and the number of procedures required (either surgery or extracorporeal shock wave lithotripsy; grade 1: 0.0 interventions per patient per year; grade 4: 0.24).

CONCLUSIONS

MSK presents over a wide age range and can cause long periods of intermittent episodes. Patients can be graded using a novel system based on IVU findings, which correlates with severity of disease. Management strategies such as intensity of follow-up can be modified using this grading.

[Cystic diseases of the kidney]

Cystic diseases of the kidney constitute a heterogeneous family. Most renal cysts are benign and asymptomatic, and don't have any impact on renal function. These "simple" cysts are usually managed conservatively. However, some renal cysts may be symptomatic or may have atypical radiological presentation, leading to suspicion of malignant tumour; puncture or surgical investigation may be indicated in such cases. The other cystic renal diseases include specific entities, either genetic or acquired during development. Some malformative syndromes are often associated, and renal function may be impaired. In such cases, nephrectomy is required.

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.

Nephrolithiasis and increased blood pressure among females with high body mass index

BACKGROUND

We hypothesized that one reason for the heterogeneity in previously reported links between kidney stones and blood pressure (BP) was the differential effects of nephrolithiasis among subgroups of individuals. In particular, we hypothesized that the association between stone history and BP may vary with respect to sex and body size.

METHODS

Data from the Third National Health and Nutrition Examination Survey were used to estimate the association between history of stone disease and odds of prior diagnosis of hypertension and mean difference in systolic BP, diastolic BP, and pulse pressure. Nine hundred nineteen persons with a history of stones and 19,120 persons without stones were available for analysis.

RESULTS

In women, it was estimated that stone formers (SFs) experienced a 69% increase in odds of self-reported hypertension (95% confidence interval [CI], 1.33 to 2.17; P < 0.001). No significant difference was found in men. The estimated difference in mean systolic and diastolic BP comparing SFs with non-SFs increased with body mass index in both sexes, but was more pronounced in women. Mean systolic BPs in women SFs in quintiles 4 and 5 of body mass index were 7.62 mm Hg (95% CI, 1.04 to 14.2; P = 0.024) and 4.36 mm Hg (95% CI, 0.30 to 8.42; P = 0.036) greater than those in similar women non-SFs, respectively.

CONCLUSION

Our findings not only support the link between kidney stone disease and BP, but also suggest that overweight women SFs may be at significantly increased risk for hypertension.

Serial crystalluria determination and the risk of recurrence in calcium stone formers

BACKGROUND

Urinary crystal precipitation is the necessary initial step in kidney stone formation. However, clinical relevance of crystalluria in the evaluation of stone formers is disputed.

METHODS

We serially determined crystalluria in first-voided morning urine samples, together with full 24-hour urine biochemistry, in 181 patients with idiopathic calcium nephrolithiasis who had formed at least one calcium-oxalate stone and were followed for at least 3 years under our care. All stone events which occurred prior to referral, then after entry in the study were recorded.

RESULTS

As compared with 109 patients who had no evidence of stone recurrence during follow-up, the 72 patients who experienced >/= one recurrent stone event had a lower daily urine volume (1.74 +/- 0.06 vs. 2.26 +/- 0.05 L/day (mean +/- SEM) (P < 0.0001), higher urine calcium and oxalate concentrations, and daily calcium excretion, and they had more frequent crystalluria (68% vs. 23% of urine samples) (P < 0.0001). By multivariate Cox regression analysis, the hazard ratio for stone recurrence was 0.32 (95% CI 0.16-0.62) for 1 L increase in daily urine volume, 1.12 (1.09-1.24) for 1 mmol/L increase in urine calcium concentration, 1.24 (1.02-1.50) for 0.1 mmol/L increase in urine oxalate concentration and 27.8 (10.2-75.6) for crystalluria index.

CONCLUSION

These data provide evidence that crystalluria, when repeatedly found in early morning urine samples, is highly predictive of the risk of stone recurrence in calcium stone formers. Serial search for crystalluria, a simple and cheap method, may be proposed as a useful tool for the monitoring of calcium stone formers, in addition to urine biochemistry.

Anticholinesterase activity of compounds related to geneserine tautomers. N-Oxides and 1,2-oxazines

A series of phenylcarbamate analogues of geneserine (8, 10, 12, 14) were synthesized from their counterparts, the phenylcarbamate analogues of physostigmine (2-5), by oxidation. The geneserine analogues can undergo tautomerism between N-oxide and 1,2-oxazine structures in a pH- and time-dependent manner. Assessment by (1)H NMR indicated that the N-oxide structure is adopted at neutral pH and that the compound exists in an equilibrium between several epimers. Evaluation of their biological action to inhibit human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), ex vivo, demonstrated that the N-oxide (7, 9, 11, 13, 15) and 1,2-oxazine (6, 8, 10, 12, 14) structures possessed similar potencies against AChE, but the latter structures were more potent against BChE. With the exception of the BChE selective inhibitor, 12, none of the geneserine analogues were as potent or enzyme subtype selective as their physostigmine analogue counterparts.

Reduced crystallization inhibition by urine from women with nephrolithiasis

BACKGROUND

Human urine is known to inhibit growth, aggregation, nucleation, and cell adhesion of calcium oxalate monohydrate (COM) crystals, the main solid phase of human kidney stones. This study tested the hypothesis that low levels of inhibition are present in women with calcium oxalate stones and, therefore, could promote stone production.

METHODS

In 17 stone-forming women and 17 normal women matched in age within five years, inhibition by dialyzed urine proteins of COM growth and aggregation was examined, as well as whole urine upper limits of metastability (ULM) for COM and calcium phosphate (CaP) in relation to the corresponding supersaturation (SS).

RESULTS

Compared to normals, patient urine showed a reduced ULM in relation to SS. In contrast to men, there was no difference in growth inhibition.

CONCLUSIONS

Reduced CaP and CaOx ULM values in relation to SS are a characteristic of female stone formers. This defect could promote stones by facilitating crystal nucleation. Abnormal inhibition may well be a very important cause of human nephrolithiasis.

Reduced crystallization inhibition by urine from men with nephrolithiasis

BACKGROUND

Human urine is known to inhibit growth, aggregation, nucleation, and cell adhesion of calcium oxalate monohydrate (COM) crystals, the main solid phase of human kidney stones. This study tests the hypothesis that low levels of inhibition are present in men with calcium oxalate stones and could therefore promote stone production.

METHODS

In 17 stone-forming men and 17 normal men that were matched in age to within five years, we studied the inhibition by dialyzed urine proteins of COM growth, aggregation, and binding to cultured BSC-1 renal cells, as well as whole urine upper limits of metastability (ULM) for COM and calcium phosphate (CaP) in relationship to the corresponding supersaturation (SS).

RESULTS

Compared with normals, patient urine showed reduced COM growth inhibition and reduced ULM in relationship to SS. When individual defects were considered, 15 of the 17 patients were abnormal in one or more inhibition measurements. ULM and growth inhibition defects frequently coexisted.

CONCLUSIONS

Reduced COM growth and CaP and CaOx ULM values in relationship to SS are a characteristic of male stone formers. Both defects could promote stones by facilitating crystal nucleation and growth. Abnormal inhibition may be a very important cause of human nephrolithiasis.

The financial effects of kidney stone prevention

Prevention of nephrolithiasis (NL) is now medically feasible and widely recommended. However, diagnosis and treatment of remediable causes of stones requires testing and drugs that impose a cost; this cost is balanced by the presumed reductions in stone related events and medical encounters. In order to assess the balance between these, we have analyzed results from 1092 patients with NL unselected except for having clinical follow-up during treatment. From this population, we have derived the changes in rates of new stones, hospitalizations, cystoscopies, and surgical procedures. From these changes, and assignment of a range of possible dollar costs, we estimate that medical stone prevention will result in an average saving of $2,158 +/- $500 (SEM)/patient/year, which is the difference between an expenditure of $1,068/patient on yearly drugs and testing, and a reduction of $3,226 per patient in medical costs. Medical prevention of NL seems justified on a cost saving basis quite apart from its benefits to patients in terms of reduced morbidity and risk from procedures, obstruction, and infection.

Familial hypomagnesemia with hypercalciuria and nephrocalcinosis

Very few patients with familial hypomagnesemia, hypercalciuria and nephrocalcinosis have been described. Information about clinical course, familial studies or evolution after renal transplantation is very scant. We have studied eight patients with this syndrome who belong to five different families. The mean age at diagnosis was 15 +/- 7 years (5 to 25 years). The primary clinical data were polyuria-polydipsia (8 cases), ocular abnormalities (5), recurrent urinary tract infections (5) and recurrent renal colics with stone passage (2). Bilateral nephrocalcinosis was observed in all cases. Every patient showed hypomagnesemia (1.1 +/- 0.2 mg/dl) with inappropriately high urinary magnesium (Mg) excretions (70 +/- 17 mg/day), Mg clearances (4.4 +/- 1.2 ml/m) and Mg fractional excretions (16.2 +/- 7.1%). Hypercalciuria was present in every case except in those with advanced renal insufficiency. Serum parathormone levels were abnormally high. Serum calcium (Ca), phosphorus and potassium, and urinary excretions of uric acid and oxalate were normal. Neither chronic oral Mg administration nor thiazide diuretics normalized serum Mg levels or urinary Ca excretions, respectively. Follow-up was 6 +/- 4.5 years. Renal function worsened in every case with six patients starting on chronic dialysis after 4.3 +/- 3.8 years. The progression rate of renal insufficiency correlated with the severity of nephrocalcinosis. Five patients have received a kidney graft, and their serum Mg and urinary Ca have always been within normal values after transplantation. Twenty-six members of four of the affected families were studied: none of them showed hypomagnesemia, renal insufficiency or nephrocalcinosis. However, eleven cases (42%) had hypercalciuria and four of them presented with recurrent renal stones. Two family members had medullary sponge kidneys. In conclusion, progression to renal insufficiency is common in this syndrome; oral Mg and thiazide diuretics are ineffective to correct abnormalities. After kidney graft, tubular handling of Mg and Ca was normal. A striking incidence (42%) of hypercalciuria was found in the familial study.

An increasing number of calcium oxalate stone events worsens treatment outcome

Current practice recommends metabolic evaluation of patients who have formed multiple renal stones, but not those with one stone or temporally remote stones. This presumes that recentness and recurrence imply greater risk of new future stones. We hypothesize that number of stones reflects how long patients are permitted to form stones untreated, and that forming more stones, itself, raises risk of future stones despite treatment. Our report is a retrospective analysis of 371 male patients selected from a comprehensive clinical and laboratory data base containing 2,527 patients with nephrolithiasis. Before treatment, number of stone events rises with time of observation, and rate of stone event occurrence is constant or falls. During treatment, relapse is correlated with number of pretreatment stones. Life table analysis showed increasing relapse for patients grouped into those with one, two, and three or more stones. Even though number of stones seems controlled by the interval of observation before treatment, more stones predict higher relapse during treatment. Perhaps by leaving nuclei of crystals as residues, stones appear to promote new stones, and the practice of waiting while patients declare themselves multiple stone formers may not always be the best.

Renal stone disease in autosomal dominant polycystic kidney disease

Nephrolithiasis is an important manifestation of autosomal dominant polycystic kidney disease (ADPKD), which occurs in approximately 20% of patients. It should always enter the differential diagnosis of flank pain in patients with ADPKD. The diagnosis is hindered by the distorted anatomy of the polycystic kidneys and the frequent occurrence of parenchymal and cyst wall calcifications, and requires demonstration of the relationship to the collecting system by intravenous urography and/or computed tomography. Computed tomography is the most sensitive imaging technique for detection of stones or calcifications, whereas intravenous urography is the most sensitive for visualization of the intrarenal collecting system. Precaliceal tubular ectasia can be detected in 15% of patients with ADPKD and nephrolithiasis, but this association may not be specific to ADPKD. The composition of the stones is most frequently uric acid and/or calcium oxalate. Metabolic factors are important in their pathogenesis. Distal acidification defects may be important in a few patients, while an abnormal transport of ammonium, low urine pH, and hypocitruria are the most common abnormalities. The treatment of nephrolithiasis in patients with ADPKD is not different from that in patients without ADPKD. Extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy in patients with early disease and normal renal function are not contraindicated.

Role of extracorporeal shock-wave lithotripsy in treatment of urolithiasis in patients with medullary sponge kidney

In an effort to identify the role of extracorporeal shock-wave lithotripsy (ESWL) in the treatment of patients with medullary sponge kidney, a retrospective review of our experience with the Dornier HM-3 lithotriptor is presented. From 1986-1991 17 patients with medullary sponge kidney ranging in age from twenty-eight to fifty-eight years received 31 treatments to a total of 24 renal units. Follow-up ranged from four to fifty-six months with an average follow-up of twenty-five months. ESWL appears to have a role in the treatment of symptomatic urolithiasis in patients with medullary sponge kidney. There may also be some benefit in treating parenchymal calcifications. No significant side effects from the treatment were noted.

Calcium and calcium magnesium carbonate specimens submitted as urinary tract stones

Of 8,129 specimens submitted as urinary stones from 6,095 patients, 67 from 15 patients were predominantly calcium carbonate or calcium magnesium carbonate (dolomite) by infrared analysis. Detailed study of 1 man and 4 women who submitted 3 or more such specimens showed that all were of aragonite calcium carbonate crystal form in 2 women and all calcite in the man. All 3 patients had a long history of nephrolithiasis preceding submission of calcium carbonate stones. There was frequent and often painful spontaneous passage of many small stones. Medullary sponge kidney was reported in 2 patients. Specimens submitted by the other 2 women included dolomite and quartz artifacts. Of the other 10 patients 4 had calcite and 1 had aragonite (possibly true stones). Five patients had artifacts with dolomite in 3 and mixed specimens in 2. True calcium carbonate kidney stones and calcium carbonate artifacts may be difficult to distinguish, and dolomite and quartz artifacts may require x-ray diffraction for clear-cut diagnosis.

Stone-forming potential of milk or calcium-fortified orange juice in idiopathic hypercalciuric adults

Milk and orange juice (OJ) fortified with calcium-citrate-malate (CCM; calcium-citrate-malate salt is a coined term to describe a trademarked calcium delivery system found only in Citrus Hill Plus Calcium) were evaluated for their potential to alter urine chemistries and crystallization during the course of an eleven week, crossover study. Six male and six female, non-stone-forming, idiopathic hypercalciuric adults consumed 600 mg per day as beverage calcium for four consecutive weeks. The results show that both milk and CCM-fortified OJ (CCM-OJ) were well tolerated by male and female hypercalciurics since few significant changes occurred in overall urinary chemistry profiles. CCM-OJ did, however, significantly (P less than or equal to 0.05) increase urinary pH relative to milk in both sexes and urinary citrate concentration in women only. Both of these urinary parameters were significantly increased by CCM-OJ in both sexes relative to the basal period. The combined pH and citrate effects are recognized to protect against calcium oxalate stone formation through formation of the soluble calcium citrate salt. These data indicate that either milk or CCM-fortified orange juice can be consumed, at least within the limits tested, as a dietary source of calcium without increasing the risk of stone formation in a calcium-sensitive subpopulation. That the urine chemistries and crystallization of such calcium-sensitive individuals does not significantly change with the consumption of either beverage implies that the urine of normal individuals would be exceedingly unlikely to change as well.

Diet, vitamin D and vertebral mineral density in hypercalciuric calcium stone formers

To elucidate the pathophysiology of dietary calcium independent hypercalciuria, 42 calcium stone formers (Ca SF) were selected because they had on free diet a calciuria greater than 0.1 mmol/kg/day. For four days they were put on a diet restricted in calcium (Ca RD) by exclusion of the dairy products. They collected 24 hour urines on free diet and on day 4 of Ca RD as well as the two-hour fasting urines on the morning of the day 5 and the four-hour urines passed after an oral calcium load of 1 g, for measurement of creatinine, Ca, PO4, urea and total hydroxyprolinuria (THP). On day 5 fasting plasma concentrations of Ca, PO4, intact PTH, Gla protein, calcidiol and calcitriol were measured. The patients were firstly classified into dietary hypercalciuria (DH, 18 patients) and dietary calcium-independent hypercalciuria (IH, 24 patients) on the basis of the disappearance or not of hypercalciuria on Ca RD. Then the patients with IH were subclassified into absorptive hypercalciuria (AH) because of normal fasting calciuria (8 patients) and into fasting hypercalciuria (16 patients). Fasting hypercalciuric patients were subsequently divided according to the PTH levels into renal hypercalciuria (RH, 1 patient) with elevated fasting PTH becoming normal after the Ca load and undetermined hypercalciuria (UH, 15 patients) with normal PTH levels. Furthermore, their vertebral mineral density (VMD) was measured by quantitative computerized tomography which was normal in DH (91 +/- 6% of the normal mean for age and sex) but was decreased in IH to 69 +/- 4%. No difference in VMD was observed between AH and UH. Urinary excretions of urea, phosphate and THP was higher in IH than in DH and comparable in AH and UH. Sodium excretion Ca RD was the same in all groups and subgroups as well as the plasma parameters. Plasma calcitriol was increased in IH and DH comparatively to normal in spite of normal plasma calcidiol. Calciuria increase after oral calcium load, an index of Ca absorption, was higher in IH than in controls and comparable in IH and DH as well as in the three subgroups of IH. From these data and correlation studies in IH it is concluded: (1.) VMD is decreased in Ca stone formers with IH but not in those with DH, making the distinction of these two groups of hypercalciuria patients clinically relevant.(ABSTRACT TRUNCATED AT 400 WORDS)

Medullary sponge kidney on axial computed tomography: comparison with excretory urography

To evaluate features of medullary sponge kidney (MSK) on computed tomography (CT), 4-mm-thick axial slices without intravenous contrast material were first made in 13 patients through 24 kidneys which showed images of MSK on excretory urograms. On CT, papillary calcifications were found in eleven kidneys. In five of these kidneys, the calcifications were not detectable on plain films. Some hyperdense papillae (attenuation value 55-70 Hounsfield units) without calcification were found in four other kidneys. Nine kidneys appeared normal. Ten of these 24 kidneys were reexamined by a second series of 4-mm-thick axial slices, 5 min after intravenous injections of 50 ml of Urografin. Images suggesting possible ectasia of precaliceal tubules were found in only four kidneys. These images appear much less obvious and characteristic on CT than on excretory urogram and do nothing more than suggest the possibility of MSK. In conclusion, the sensitivity of CT in the detection of MSK is markedly lower than that of excretory urography. In the most florid cases of the disease, CT can only show images suggesting the possibility of MSK. On the other hand, CT appears much more sensitive than plain films and tomograms of excretory urography in the detection of papillary calcifications, the most frequent complication of MSK.

Clinical and laboratory approaches for evaluation of nephrolithiasis

The initial part of this presentation deals with the sensitivity of tests commonly used in the diagnosis of primary hyperparathyroidism. Total serum calcium levels often are normal in patients with small parathyroid adenomas but levels of serum ultrafilterable and/or ionized calcium usually are elevated in these patients. The recent introduction of improved radioimmunoassays for measurement of circulating parathyroid hormone has led to greatly improved sensitivity of this test for the diagnosis of primary hyperparathyroidism. However, measurement of total urinary cyclic adenosine monophosphate, even when expressed as a function of glomerular filtration rate, is an extremely insensitive test in patients who have parathyroid adenomas weighing less than 1 gm. Consequently, this test no longer is used for diagnostic purposes in our laboratory. Data relating to the prevalence and causes of hyperoxaluria in patients with idiopathic calcium oxalate stones also are presented. Hyperoxaluria (more than 450 mumol. per 24 hours) was found in 21 of 99 consecutive untreated male patients. Approximately a third of the patients with high normal or increased urinary oxalate excretion also have increased urinary glycolate excretion, which is indicative of increased endogenous oxalate production. This metabolic abnormality was unresponsive to pyridoxine administration but preliminary findings suggest that it may be corrected by restricting dietary protein.

The association of nephrolithiasis and autosomal dominant polycystic kidney disease

Despite the frequency and morbidity of nephrolithiasis in autosomal dominant polycystic kidney disease (ADPKD), this association has not been subject to a detailed study. One hundred fifty-one of 751 ADPKD patients seen at the Mayo Clinic between 1976 and 1986 had nephrolithiasis. Seventy-four had passed calculi or had stones surgically removed. Stone analysis was available in 30 patients: uric acid, calcium oxalate, calcium phosphate, and struvite were present in 56.6%, 46.6%, 20%, and 10%, respectively. Calculi were observed in 71 of 79 patients with excretory urograms available for review. Faintly opaque and bull's eye stones, probably containing uric acid, were present in 12.7% and 14.1% of these patients, respectively. Precaliceal tubular ectasia was observed in 15.5%. Ninety-seven patients had preserved renal function (serum creatinine less than 1.5 mg/dL) at the initial evaluation. Six were excluded because they had other known causes of stone disease. The most common metabolic abnormality in the remaining 91 patients was hypocitric aciduria (ten of 15 patients with measurements). The urine pH in the first voided morning specimens (5.66 +/- 0.05) was significantly lower than that of an unselected control population (5.92 +/- 0.03, P less than 0.001). Hyperuricosuria, hyperoxaluria, and hypercalciuria were observed in six of 32 (18.8%), six of 31 (19.4%), and three of 39 (9.7%) patients with preserved renal function. The composition of the stones, the frequency of hypocitric aciduria, and the low urine pH (possibly related to the defect in excretion of ammonia described in ADPKD), suggest that metabolic, along with mechanical, factors are responsible for the frequent occurrence of nephrolithiasis in this disease.

Renal hypercalciuria and metabolic acidosis associated with medullary sponge kidney: effect of alkali therapy

Sixteen patients with medullary sponge kidney (MSK) and renal stones underwent evaluation of calcium metabolism and acid base balance. Six normal subjects and eight patients with non-MSK absorptive hypercalciuria served as control. Nine (56%) were hypercalciuric and seven (44%) were normocalciuric (N-MSK). Hypercalciuria was divided into absorptive (AH-MSK, n = 2) and renal leak hyerpcalciuria (RH-MSK, n = 7). The mean of minimal urine pH of RH-MSK group (5.28 +/- 0.09 (SE] was significantly higher than that of normal control (4.78 +/- 0.12) and of non-MSK AH (4.80 +/- 0.6) during acute acid challenge. The mean of the arterial blood HCO3 concentration of RH-MSK group was significantly lower than that of two control groups. The urine calcium and a frequency of stone passage were decreased significantly after alkali treatment in RH-MSK.

Reduced glomerular filtration rate and hypercalciuria in primary struvite nephrolithiasis

Struvite nephrolithiasis is caused by infection with bacteria that possess the enzyme urease, and convert urea to ammonia that raises urine pH and crystallizes with magnesium and trivalent phosphate ion. Of the 75 of our 1431 stone patients with struvite stones 52 were women. Struvite stones occurred almost exclusively in women; a minority of women and most men had mixed stones of struvite and calcium oxalate. Increased serum creatinine levels and reduced creatinine clearance were common in patients with struvite stones, not in those with mixed stones; both were rare in calcium stone disease. Men and women with mixed struvite, calcium oxalate stones were hypercalciuric, but women with struvite stones were not. Patients with mixed stones usually had initial symptoms of stone passage, and were less likely to need surgery, including nephrectomy, or to form contralateral stones. Patients with struvite stones usually presented with infection or no symptom, not passage. We conclude that struvite stones occur in two forms. The struvite stone is a disease of women, presumably occurring de novo from infection. The mixed stones occur in both sexes, presumably from secondary infection in hypercalciuric patients who begin with calcium-oxalate stone disease.

A urinary calcium-citrate index for the evaluation of nephrolithiasis

We have performed a multivariate analysis of urine abnormalities in patients with calcium oxalate nephrolithiasis, in which effects of gender were also considered. The characteristic of patients that most clearly sets them apart from normal people is a high level of urine calcium for any given level of urine citrate. Other urine measurements cannot improve upon the separation between patients and normals provided by urine calcium and citrate, and their abnormal relationship to each other. Normal women have higher urine citrate and lower urine calcium than normal men or patients of either sex; normal men differ from stone forming men only moderately. Direct measurements of supersaturation are not helpful in distinguishing between patients and normals, once calcium and citrate have been considered. From our analysis, we have derived a new index for evaluating the significance of urine calcium and citrate levels that seems to offer a better basis for clinical diagnosis than criteria presently in use.