Risk factors and implications associated with ultrasound-diagnosed nephrocalcinosis in cats with chronic kidney disease

BACKGROUND

Microscopic nephrocalcinosis is a common pathological feature of chronic kidney disease (CKD) in cats. Detection of macroscopic nephrocalcinosis using ultrasonography and its implications remain unexplored.

OBJECTIVES

Identify risk factors associated with ultrasound-diagnosed nephrocalcinosis and evaluate the influence of nephrocalcinosis on CKD progression.

ANIMALS

Thirty-six euthyroid client-owned cats with CKD.

METHODS

Prospective cohort study. Cats with CKD with and without ionized hypercalcemia were enrolled for renal ultrasonography. Cats were categorized according to the presence or absence of ultrasound-diagnosed nephrocalcinosis. Binary logistic regression was performed to identify nephrocalcinosis risk factors. The influence of nephrocalcinosis on CKD progression was assessed using linear mixed models.

RESULTS

Ultrasound-diagnosed nephrocalcinosis was evident in 61% of CKD cats overall, with increased prevalence (81%) in those with hypercalcemia. At enrollment, higher blood ionized calcium concentration (odds ratio [OR], 1.27 per 0.1 mg/dL; P = .01), plasma phosphate concentration (OR, 1.16 per 0.1 mg/dL; P = .05), plasma creatinine concentration (OR, 1.29 per 0.1 mg/dL; P = .02) and alanine aminotransferase activity (OR, 2.08 per 10 U/L; P = .04) were independent nephrocalcinosis risk factors. The rate of change in log-transformed fibroblast growth factor-23 differed significantly between groups (P = .04). Cats with CKD and nephrocalcinosis had increasing plasma creatinine concentrations (.03 ± .01 mg/dL/month; P = .04) and phosphate concentrations (.06 ± .02 mg/dL/month; P < .001) and decreasing body weight (.02 ± .01 kg/month; P < .001) over time.

CONCLUSIONS AND CLINICAL IMPORTANCE

Nephrocalcinosis is prevalent in cats with CKD, especially in those with hypercalcemia. This pathological feature appears to be associated with CKD progression in cats.

Detection of nephrocalcinosis using ultrasonography, micro-computed tomography, and histopathology in cats

BACKGROUND

Identification of nephrocalcinosis in cats with chronic kidney disease (CKD) is of clinical interest but the ability of ultrasonography to detect nephrocalcinosis is uncertain.

OBJECTIVES

To compare ultrasonography, micro-computed tomography (μCT) and histopathology for identification of nephrocalcinosis.

ANIMALS

Twelve kidneys from 7 euthyroid client-owned cats with CKD.

METHODS

Descriptive study. Renal ultrasonography was performed ante-mortem for nephrocalcinosis detection. Kidneys were grouped based on nephrocalcinosis: present, suspected, or absent. When cats died, necropsy was performed. Renal tissue was evaluated using μCT for macroscopic nephrocalcinosis, and nephrocalcinosis volume-to-kidney tissue ratio (macro-VN:KT) and sagittal nephrocalcinosis area-to-kidney tissue ratio (macro-AN:KT) were calculated. Each kidney subsequently was bisected longitudinally, formalin-fixed, and paraffin-embedded for microscopic nephrocalcinosis assessment using von Kossa and Alizarin red staining with AN:KT (VK-micro-AN:KT and AR-micro-AN:KT) quantified using ImageJ. Data are presented as median (range). Relationships between macroscopic and microscopic AN:KT were assessed using Spearman's correlation.

RESULTS

Nephrocalcinosis by ultrasonography was considered to be absent in 3, suspected in 3, and present in 5 kidneys; 1 kidney had nephrolithiasis with nephrocalcinosis. The macro-VN:KT was 0.001%, 0.001%, and 0.019%, and the macro-AN:KT was 0.08%, 0.30%, and 1.47%, respectively. Histologically, VK-micro-AN:KT was 0.21%, 2.85%, and 4.56%, and AR-micro-AN:KT was 1.73%, 5.82%, and 8.90% for kidneys where ultrasonographic macro-nephrocalcinosis was absent, suspected, or present, respectively. A strong correlation was identified between macroscopic (macro-AN:KT) and microscopic (VK-micro-AN:KT) nephrocalcinosis (rs = 0.76; P = .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

Ultrasonographically diagnosed nephrocalcinosis correlates well with macroscopic and microscopic nephrocalcinosis at necropsy despite their separation in time.

Enamel renal syndrome: A case report with calcifications in pulp, gingivae, dental follicle and kidneys

BACKGROUND

Enamel renal syndrome is a rare genetic disorder transmitted through an autosomal recessive mode. It is featured by a hypoplastic amelogenesis imperfecta, delayed tooth eruption, gingival fibromatosis, and nephrocalcinosis. The aim of this study was to describe clinically, radiologically, and histologically the main features of enamel renal syndrome and to point out the role of dentists in early diagnosing this genetic disease.

MATERIALS AND METHODS

Our case of enamel renal syndrome was initially described by clinical, radiographic, and genealogic data, then complemented by ultrasound examination of the kidneys and microscopic observation of gingivae.

RESULTS

The study showed the presence of amelogenesis imperfecta (AI), several teeth impaction, gingival hyperplasia, bilateral nephrocalcinosis, and multiple calcifications in pulp, gingiva, dental follicle, and kidneys.

CONCLUSION

The patient was followed for a full mouth rehabilitation and also referred to a nephrology for global medical checkup. The dentist plays a key role in diagnosing genetic diseases and in referring patients for medical comprehensive care.

Nephrolithiasis and/or nephrocalcinosis is significantly related to renal dysfunction in patients with primary Sjögren's syndrome

OBJECTIVE

The present study compared the clinical features of patients with primary Sjögren's syndrome (pSS) with and without nephrolithiasis and/or nephrocalcinosis to determine factors related to renal dysfunction.

METHODS

The clinical features of 68 patients with anti-Sjogren's syndrome antigen A (SSA)/Ro-antibody-positive pSS with and without nephrolithiasis and/or nephrocalcinosis who underwent abdominal computed tomography and/or ultrasonography were retrospectively analysed.

RESULTS

Of the 68 patients with anti-SSA-antibody-positive pSS, 23 (33%) had renal nephrolithiasis and/or nephrocalcinosis, whereas 45 (67%) did not. Fourteen (20%) patients had renal dysfunction at diagnostic imaging. Among five patients who underwent renal biopsy, four patients with renal nephrolithiasis and/or nephrocalcinosis were diagnosed with tubulointerstitial nephritis, and one without nephrolithiasis and/or nephrocalcinosis was diagnosed with minimal change nephrotic syndrome. Estimated glomerular filtration rate at diagnostic imaging was significantly lower in patients with than without nephrolithiasis and/or nephrocalcinosis group (P = 0.010). In addition to nephrolithiasis and/or nephrocalcinosis (odds ratio [OR], 3.467; P = 0.045), the gap between serum sodium and chloride concentrations (OR, 10.400; P = 0.012) and increased urinary β2-microglobulin (OR, 5.444; P = 0.033) were associated with renal dysfunction at the time of diagnostic imaging.

CONCLUSION

Nephrolithiasis and/or nephrocalcinosis, normal anion gap metabolic acidosis, and tubulointerstitial damage are associated with renal dysfunction in patients with pSS.

Nephrocalcinosis in a Transplanted Kidney: A New Sign of Chronic Tacrolimus Nephrotoxicity

Calcineurin inhibitors are potent immunosuppressive drugs in solid-organ transplantation and multiple autoimmune diseases. Their use is associated with the acute impairment of glomerular filtration and chronic interstitial fibrosis. The latter is mediated by the accumulation of matrix proteins. In this case report, we present a kidney transplant patient with chronic and progressive allograft failure that was associated with nephrocalcinosis. He did not have hypercalcemic-hypercalciuric states such as hyperparathyroidism, sarcoidosis, and hyper-vitaminosis D; normocalcemic-hypercalciuric states such as distal renal tubular acidosis, medullary sponge kidney, excessive use of high-dose loop diuretics, and beta-thalassemia; hyperphosphaturic conditions; and hyperoxaluria. Moreover, his calcifications were limited to the transplanted kidney and spared the native kidneys and extrarenal tissues, and his renal function had improved and stabilized for 6 months after discontinuation of prolonged-release tacrolimus (Advagraf), indicating a cause and an effect phenomenon. Nephrocalcinosis was suspected after ultrasonography and confirmed by computed tomography scanning. Hence, allograft nephrocalcinosis may indicate chronic tacrolimus nephrotoxicity.

[Encrusted Pyelitis during a case of Thrombotic Thrombocytopenic Purpura]

Encrusted pyelitis is a chronic urinary tract infection associated with mucosal encrustation induced by urea splitting bacteria. More than 40 bacteria have been implicated but the most frequent is Corynebacterium group D2. Predisposing factors are debilitating chronic diseases and preexisting urological procedures. Immunosoppression is an important cofactor. For these reasons the disease is almost always nosocomially acquired and renal transplant recipients are at particular risk. The symptoms are not specific and long lasting: dysuria, flank pain and gross haematuria are the most frequent; fever is present in two-thirds. The demonstration of urine splitting bacteria in constantly alkaline urines and radiological evidence of extensive calcification of pelvicalyceal system, ureter and bladder at US or CT scan in a clinical context of predisposing factors are the mainstay of diagnosis. Treatment is based on adapted antibiotic therapy, acidification of urine and excision of plaques of calcified encrustation. The prognosis relies on timing of diagnosis; delay can be detrimental and result in patient's death and graft loss. We describe a unique case of 69-year-old man with two contemporary diseases: autoimmune thrombotic thrombocytopenic purpura and encrusted pyelitis with a fatal evolution.

Prosthetic Rehabilitation of a Patient with Rare and Severe Enamel Renal Syndrome

Dental rehabilitation of acute cases of enamel renal syndrome is challenging due to the absence of clinical reports. In the present case history report, examination of an 18-year-old patient revealed a complete lack of permanent teeth, as well as irregular and swollen bone and gingival morphology. Radiographs showed multiple impacted teeth in both arches. Creating a 1.5- to 2-cm interarch space was necessary for setting complete dentures. The ideal occlusal plane was chosen by combining two techniques (cephalometric radiograph and modification of the mandibular occlusal rim according to anatomical guidelines). Extraction of impacted teeth and recontouring of the alveolar process were performed simultaneously. The mandibular denture was connected through Locator abutments to two symphyseal implants. This pioneering clinical report will provide guidance to practitioners in the surgical intervention of patients with FAM20A (family with sequence similarities 20 A) gene mutations.

Rare case of nephrocalcinosis in a 14-year-old girl: Questions

A 14-year-old Caucasian girl with a history of primary hypoparathyroidism and unstable calcium and phosphorus levels and on ongoing treatment was admitted to the Department of Pediatric Nephrology because of the onset of nephrocalcinosis and difficulties achieving normocalcemia. Coexistence of hypoparathyroidism, oral candidiasis, dental enamel hypoplasia, and subclinical Hashimoto's disease was strongly suggestive for autoimmune polyglandular syndrome (APS) type I. One of the clinical implications of this diagnosis is the high probability of future occurrence of adrenal insufficiency and hence the importance of maintaining a high level of suspicion in case of the onset of symptoms like weakness, fainting, hypotonia, or hyperkaliemia. Addison's disease would, in fact, be quite challenging for the future management of this patient.This clinical quiz highlighted the importance of careful evaluation of all multiorgan symptoms occurring in a patient to prevent further complications.

Hypoparathyroidism and pseudohypoparathyroidism: etiology, laboratory features and complications

OBJECTIVES

To identify a clinical profile and laboratory findings of a cohort of hypoparathyroidism patients and determine the prevalence and predictors for renal abnormalities.

MATERIALS AND METHODS

Data from medical records of five different visits were obtained, focusing on therapeutic doses of calcium and vitamin D, on laboratory tests and renal ultrasonography (USG).

RESULTS

Fifty-five patients were identified, 42 females and 13 males; mean age of 44.5 and average time of the disease of 11.2 years. The most frequent etiology was post-surgical. Levels of serum calcium and creatinine increased between the first and last visits (p < 0.001 and p < 0.05, respectively); and serum levels of phosphate decreased during the same period (p < 0.001). Out of the 55 patients, 40 had USG, and 10 (25%) presented with kidney calcifications. There was no significant difference in the amount of calcium and vitamin D doses among patients with kidney calcifications and others. No correlation between serum and urinary levels of calcium and the presence of calcification was found. Urinary calcium excretion in 24h was significantly higher in patients with kidney calcification (3.3 mg/kg/d) than in those without calcification (1.8 mg/kg/d) (p < 0.05).

CONCLUSIONS

The reduction of hypocalcemia and hyperphosphatemia suggest an effectiveness of the treatment, and the increase in serum creatinine demonstrates an impairment of renal function during follow-up. Kidney calcifications were prevalent in this cohort, and higher urinary calcium excretion, even if still within the normal range, was associated with development of calcification. These findings suggest that lower rates of urinary calcium excretion should be aimed for in the management of hypoparathyroidism.

Prevalence of renal abnormality in pediatric intestinal failure

BACKGROUND

Outcomes of children with intestinal failure have improved over the last decade. However, with improved survival, other co-morbidities have become evident. The goal of our study was to evaluate the presence of renal nephrocalcinosis or increased echogenicity in a cohort of patients with pediatric intestinal failure (PIF).

METHODS

A cross-sectional prevalence design was performed in PIF patients followed by our intestinal rehabilitation program between 2013 and 2014. Renal function was evaluated using serum creatinine and urea, urine oxalate, creatinine, calcium, and calcium/creatinine ratios. Renal ultrasounds were performed to assess for echogenicity. Data was collected on intestinal failure related factors and nutritional intake. Data was analyzed using medians and Mann-Whitney U or proportions and chi square.

RESULTS

Fifty-four patients (median age 48months; 33 males (61%) were studied. Twenty-two patients (41%) had increased echogenicity or nephrocalcinosis on ultrasound. There were no differences in serum Creatinine or urea, but patients with nephrocalcinosis had statistically different calcium:creatinine ratio (1.69 vs 0.74; p=0.043), urine oxalate (108 vs 219; p=0.06), and serum phosphate (1.55 vs 1.75; p=0.044). Patients with echogenicity had a shorter colonic remnant (25cm vs 31cm; p=0.01), a history of longer PN exposure (928 vs 483days; p=0.05), percent PN calories (37 vs 0; p=0.05), PN h/day (13 vs 0; p=0.05), but no difference in PN Ca/phosphate/magnesium content (mmol/kg).

CONCLUSION

A large proportion of PIF patients have increased echogenicity/nephrocalcinosis on ultrasound that is associated with prolonged PN exposure. This has implications for long-term management. Regular surveillance is required, and further study is warranted to determine specific risk factors.

The Impact of Hypoparathyroidism Treatment on the Kidney in Children: Long-Term Retrospective Follow-Up Study

CONTEXT

Adults with hypoparathyroidism have significant rates of nephrocalcinosis and impaired renal function. Little is known about the impact of hypoparathyroidism treatment on renal function in children.

OBJECTIVES

To determine the prevalence and predictors for renal abnormalities (nephrocalcinosis and decreased estimated glomerular filtration rate [eGFR]) in children with treated hypoparathyroidism.

DESIGN AND SETTING

A retrospective chart review of patients with permanent hypoparathyroidism at the Hospital for Sick Children, Toronto, between 1996 and 2013.

PATIENTS

Data of 29 patients (15 males) followed for at least 1 year with documented hypoparathyroidism were analyzed. Mean duration of follow up was 7.4 ± 5 years.

MAIN OUTCOME MEASURES

The presence or absence of nephrocalcinosis as detected on ultrasound and eGFR were evaluated.

RESULTS

Time-weighted average serum measurements were calculated for all biochemical variables. Mean total and ionized serum calcium were 8.9 ± 0.8 and 4.6 ± 0.5 mg/dL, respectively. Nephrocalcinosis was observed in 38% of the subjects, with the most significant predictors being the degree of relative hypercalcemia and hyperphosphatemia (R(2) = 0.47, P < .01). Although all patients had an eGFR greater than 60, in 45% of the children, the eGRF was between 60 and 90 mL/min per 1.73 m(2). Higher calcium concentrations (r = -0.42, P = .02) and a greater proportion of time with relative hypercalcemia (r = -0.41, P = .03) were associated with lower eGFR.

CONCLUSIONS

Our results establish that children with hypoparathyroidism treated with calcitriol and calcium supplements are at risk for nephrocalcinosis and decreased eGFR. Because hypoparathyroidism is most commonly a life-long condition, careful monitoring and management of calcium abnormalities has important future implications.

Nephrocalcinosis in Calcium Stone Formers Who Do Not have Systemic Disease

PURPOSE

Nephrocalcinosis is commonly present in primary hyperparathyroidism, distal renal tubular acidosis and medullary sponge kidney disease. To our knowledge it has not been studied in patients with calcium phosphate stones who do not have systemic disease.

MATERIALS AND METHODS

We studied patients undergoing percutaneous nephrolithotomy who had calcium phosphate or calcium oxalate stones and did not have hyperparathyroidism, distal renal tubular acidosis or medullary sponge kidney disease. On postoperative day 1 all patients underwent noncontrast computerized tomography. If there were no residual calcifications, the patient was categorized as not having nephrocalcinosis. If there were residual calcifications, the patient underwent secondary percutaneous nephrolithotomy. If the calcifications were found to be stones, the patient was categorized as not having nephrocalcinosis. If the calcifications were not stones, the patient was categorized as having nephrocalcinosis. Patients were grouped based on the type of stones that formed, including hydroxyapatite, brushite and idiopathic calcium oxalate. The extent of nephrocalcinosis was quantified as 0--absent nephrocalcinosis to 3--extensive nephrocalcinosis. Patients with residual calcifications on postoperative day 1 noncontrast computerized tomography who did not undergo secondary percutaneous nephrolithotomy were excluded from analysis. The presence or absence of nephrocalcinosis was correlated with metabolic studies.

RESULTS

A total of 67 patients were studied, including 14 with hydroxyapatite, 19 with brushite and 34 with idiopathic calcium oxalate calculi. Nephrocalcinosis was present in 10 of 14 (71.4%), 11 of 19 (57.9%) and 6 of 34 patients (17.6%) in the hydroxyapatite, brushite and idiopathic calcium oxalate groups, respectively (chi-square p = 0.01). The mean extent of nephrocalcinosis per group was 1.98, 1.32 and 0.18 for hydroxyapatite, brushite and idiopathic calcium oxalate, respectively (p ≤0.001). The presence of nephrocalcinosis positively correlated with urine calcium excretion (mean ± SD 287.39 ± 112.49 vs 223.68 ± 100.67 mg per day, p = 0.03).

CONCLUSIONS

Patients without systemic disease who form hydroxyapatite and brushite stones commonly have coexistent nephrocalcinosis. Nephrocalcinosis can occur in calcium oxalate stone formers but the quantity and frequency of nephrocalcinosis in this group are dramatically less.

Chondrocalcinosis related to familial hypomagnesemia with hypercalciuria and nephrocalcinosis

Calcium pyrophosphate dehydrate (CPPD) crystal deposition disease (also known as chondrocalcinosis, CC) is a rare metabolic arthropathy mostly seen in elderly patients. Chondrocalcinosis may be associated with metabolic diseases such as hypomagnesemia when it occurs in young people. We report here a case with hypomagnesemia due to familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) who developed CC during clinical follow-up. To our best knowledge this is the first case of a young patient with CPPD associated with FHHNC.

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.

Ultrasound is superior to computed tomography for assessment of medullary nephrocalcinosis in hypoparathyroidism

CONTEXT

Nephrocalcinosis is a complication of hypoparathyroidism and other metabolic disorders. Imaging modalities include ultrasonography (US) and computed tomography (CT). Few studies have compared these modalities, and standard clinical practice is not defined.

OBJECTIVE

The objective of the study was to determine the preferred method for assessing nephrocalcinosis.

DESIGN

The design of the study was a retrospective, blinded analysis.

SETTING

The study was conducted at a clinical research center.

PATIENTS

Twenty-two hypoparathyroid subjects and 7 controls participated in the study.

INTERVENTIONS

Contemporaneous renal US and CT images were reviewed in triplicate by 4 blinded radiologists. Nephrocalcinosis was classified using a 0-3 scale with 0 meaning no nephrocalcinosis and 3 meaning severe nephrocalcinosis.

MAIN OUTCOME MEASURES

Intraobserver, interobserver, and interdevice agreements were measured.

RESULTS

Intraobserver agreement was high, with an overall weighted kappa of 0.83 for CT and 0.89 for US. Interobserver agreement was similar between modalities, with kappas of 0.74 for US and 0.70 for CT. Only moderate agreement was found between US and CT scores, with an intermodality kappa of 0.47 and 60% concordance. Of discordant pairs, 81% had higher US scores and only 19% had higher CT scores. Of nephrocalcinosis seen on US and not CT, 45%, 46%, and 9% were grades 1, 2, and 3, respectively. Overall, US scores were higher than CT with a cumulative odds ratio (95% confidence interval) of 5.97 (2.60, 13.75) (P < .01). In controls, 100% of US ratings were 0, and 95% of CT ratings were 0.

CONCLUSIONS

US is superior to CT for assessment of mild to moderate nephrocalcinosis in patients with hypoparathyroidism. This finding, in combination with its low cost, lack of radiation, and portability, defines US as the preferred modality for assessment of nephrocalcinosis.

Electrolyte imbalances and nephrocalcinosis in acute phosphate poisoning on chronic type 1 renal tubular acidosis due to Sjögren's syndrome

Although renal calcium crystal deposits (nephrocalcinosis) may occur in acute phosphate poisoning as well as type 1 renal tubular acidosis (RTA), hyperphosphatemic hypocalcemia is common in the former while normocalcemic hypokalemia is typical in the latter. Here, as a unique coexistence of these two seperated clinical entities, we report a 30-yr-old woman presenting with carpal spasm related to hypocalcemia (ionized calcium of 1.90 mM/L) due to acute phosphate poisoning after oral sodium phosphate bowel preparation, which resolved rapidly after calcium gluconate intravenously. Subsequently, type 1 RTA due to Sjögren's syndrome was unveiled by sustained hypokalemia (3.3 to 3.4 mEq/L), persistent alkaline urine pH (> 6.0) despite metabolic acidosis, and medullary nephrocalcinosis. Through this case report, the differential points of nephrocalcinosis and electrolyte imbalances between them are discussed, and focused more on diagnostic tests and managements of type 1 RTA.

Primary hyperoxaluria type 1 in Tunisian children

To determine the clinical, biological, and radiological futures of primary hyper-oxaluria type 1 in Tunisian children, we retrospectively studied 44 children with primary hyper-oxaluria type 1 who were treated in our center from 1995 to 2009. The diagnosis was established by quantitative urinary oxalate excretion. In patients with renal impairment, the diagnosis was made by infrared spectroscopy of stones or kidney biopsies. The male-to-female ratio was 1:2. The median age at diagnosis was 5.75 years. About 43% of the patients were diagnosed before the age of five years with initial symptoms dominated by uremia. Four patients were asymptomatic and diagnosed by sibling screenings of known patients. Nephrocalcinosis was present in all the patients; it was cortical in 34%, medullary in 32%, and global in 34%. At diagnosis, 12 (27%) children were in end-stage renal disease. Pyridoxine response, which is defined by a reduction in urine oxalate excretion of 60% or more, was obtained in 27% of the cases. In the majority of patients, the clinical expression of primary hyperoxaluria type 1 was characterized by nephrocalcinosis, urolithiasis, and renal failure; pyridoxine sensitivity was associated with better outcome.

[Primary hyperparathyroidism as a cause of chronic renal failure]

Nephrocalcinosis is a rare cause of chronic renal failure. We describe a 64 year-old man, who was admitted to hospital due to chronic renal failure. An ultrasound examination and a computed tomography of the kidneys showed bilateral, severe nephrocalcinosis. He had hypercalcaemia, hyperparathyroidism, and a bone disease caused by an adenoma in one of the parathyroid glands. After removal of the adenoma, the plasma calcium level was in control, but renal function deteriorated. The patient was treated with dialysis and renal transplantation.

Childhood idiopathic hypercalciuria

OBJECTIVE

To evaluate the clinical significance of renal calyceal microlithiasis (RCM) in children with idiopathic hypercalciuria (IHC).

MATERIAL AND METHODS

RCM is a renal echographic finding defined as the presence of hyperechogenic spots < 3 mm in diameter in the renal calyces. These spots have been associated with the presence of nephrourological symptoms in children and are considered to represent a stage prior to urolithiasis. We reviewed the medical records of 103 children (63 girls, 40 boys; age range 1-14 years; mean age 6.57 years) referred for various complaints who had IHC. Renal echography was routinely performed. At diagnosis, 52 children had RCM, 35 showed normal echography, 14 had calculi and two presented nephrocalcinosis. A long-term follow-up study was carried out to compare the clinical manifestations, analytic data and renal echographic findings of patients with RCM and those with normal echography.

RESULTS

The clinical manifestations and the results of biochemical studies did not differ significantly between the two groups. Renal sonographic findings during the follow-up period revealed that, of patients with initial RCM, 35 showed normalized sonographic findings, two developed calculi and 36 developed recurrent RCM. Of the children with normal initial echography, 17 developed RCM and three developed calculi. The risk of developing lithiasis was less in children with RCM than in those with normal initial renal echography (0.04 vs 0.09), the relative risk being 0.45 (95% CI 0.08-2.55). The clinical and analytic differences between the group of 14 children with initial lithiasis and the other two groups previously described were also analyzed and no significant differences were found. An ongoing echographic study of these patients showed that the echograph was normalized in 10 children at some point or other, while seven developed RCM (four unilateral, three bilateral). In 13 cases the lithiasis reappeared, and the relative risk of recurrent lithiasis compared with those who initially showed no lithiasis was 16.16 (CI 95% 6.81-38.31).

CONCLUSION

Our results indicate that up to 85% of children with IHC presented RCM in follow-up sonographies. This echographic finding, which may appear and disappear at different points during follow-up, does not seem to indicate an increased risk of lithiasis.

The effect of sodium thiosulfate administration on nephrocalcinosis in a rat model

INTRODUCTION

Sodium thiosulfate (STS) is a U.S. Food and Drug Administration (FDA)-approved chelating agent that is used for the treatment of cyanide poisoning and prophylaxis against cisplatin nephropathy. Recently, STS has also been used in the treatment of calciphylaxis, which is a disease characterized by calcification in the soft tissues with vascular calcification and thrombosis causing nonhealing ulcers. We proposed a rat model to evaluate whether STS has any possible beneficial effect on calcium nephrolithiasis or nephrocalcinosis.

METHODS

Twenty-one male Sprague-Dawley rats were used in the study. All animals received standard rat chow throughout the experiment. The animals were started on special drinking water containing 0.4% ethylene glycol plus 1.0% ammonium chloride for 7 days to induce crystalluria and nephrocalcinosis. The animals were then randomized to two groups. Group 1 served as a control and received daily intraperitoneal injections of normal saline. Group 2 received daily intraperitoneal injections of STS solution. Special drinking water containing 0.8% ethylene glycol was continued during the treatment period.

RESULTS

Group 2 gained significantly less weight than group 1 (18.0% v 8.5%, p < 0.05). The amount of crystalluria in group 2 was much less than that in group 1, but did not reach statistical significance (0.7 v 4.2, p = 0.09). Degree of calcification noted in the kidneys was not statistically different between the two groups.

CONCLUSIONS

The current study did not reveal any significant benefit of STS administration on calcium stone disease. However, many more studies are necessary before the possibility of a beneficial effect is completely disproved.

Renal tubular dysfunction with nephrocalcinosis in a patient with beta thalassemia minor

Thalassemia is a hereditary anemia resulting from defect in hemoglobin production. Beta thalassemia is due to impaired production of beta globin chains, leading to a relative excess of alpha globin chains. The term beta thalassemia minor is used to describe heterozygotes, who carry one normal beta globin allele and one beta thalassemic allele. The vast majority of these patients are asymptomatic. However, a variety of renal tubular abnormalities including hypercalciuria, hypo-magnesemia with renal magnesium wasting, decreased tubular absorption of phosphorus, hypo-uricemia with renal uric acid wasting, renal glycosuria and tubular proteinuria have been described even in patients with beta thalassemia minor. We here in report a 24-year old female patient who was found to have thalassemia minor and nephrocalcinosis with evidence of renal tubular dysfunction. Investigations revealed normal renal function, hypercalciuria, reduced tubular reabsorption of phosphorus, hypomagnesemia and renal magnesium wasting. Screening for aminoaciduria was found to be negative. An acid loading test revealed normal urinary acidification. Ultrasonogram of the abdomen revealed nephrocalcinosis and splenomegaly. Detailed work up for anemia showed normal white cell and platelet count while peripheral smear showed microcytic hypochromic anemia with few target cells. Hemoglobin electrophoresis revealed hemoglobin A of 92%, hemoglobin A2 of 6.2% and hemo-globin F of 1.8% consistent with beta thalassemia minor. Her parental screening was normal. A diagnosis of beta thalassemia minor with renal tubular dysfunction was made and the patient was started on thiazide diuretics to reduce hypercalciuria and advised regular follow-up.

[Bartter syndrome and it's neonatal type]

For the first time neonatal variant of Bartter syndrome to 14.5-year old girl is presented in Lithuania. It is a rare genetical disease with autosomal recessive inheritance. The patient was born prematurely, had polyhydramnion, polyuria and polydypsia, a craving for salt, specific outlook and was mentally retarded, had muscle weakness and nephrocalcinosis. Hypokalemia, hyperreninemia and metabolic alkalosis were found. Urine analysis revealed impaired renal concentration capacity, hypercalciuria and hypernatriuria. She had the symptom of systemic disease - osteopenia. Literature review on Bartter's syndrome is done.

Rare variant of Lesch-Nyhan syndrome without self-mutilation or nephrolithiasis

Lesch-Nyhan syndrome is a very rare X-linked recessive disorder characterized by mental retardation, spasticity resembling cerebral palsy, choreo-athetosis, self-mutilation and hyperuricemia. Self-mutilative behavior is a hallmark of the disease. Hyperuricemia leads to hyperuricuria and uric acid nephrolithiasis. The underlying defect is a deficiency of hypoxanthine-guanine-phosphoribosyl transferase. We report on a 7-year-old boy with Lesch-Nyhan syndrome, lacking self-mutilative behavior, who was erroneously diagnosed as having athetotic cerebral palsy. He also had no renal stones; hyperechoic renal medullary pyramids were the only renal abnormality detected and were sonographically indistinguishable from medullary nephrocalcinosis.

A critical appraisal of the radiological evaluation of nephrocalcinosis

BACKGROUND/AIM

The level of agreement concerning the diagnosis of nephrocalcinosis (NC) based on ultrasonography (US), computed tomography (CT) or kidney/ureter/bladder (KUB) X-ray was assessed.

METHODS

Sequences of KUB+US+CT from 62 patients, 48 with at least one exam suggesting NC and 14 with pelvicalyceal calcifications (nephrolithiasis) were reviewed twice by 3 radiologists (firstly randomized and secondly presenting KUB+US+CT of each patient together).

RESULTS

The intraobserver concordance varied from 76 to 90% for KUB, 77 to 85% for US and 82 to 89% for CT. There was a significant change in diagnosis between the 1st and 2nd reviews for observer 1 in KUB and CT, for observer 2 in US, but not for observer 3. Evaluating patients' exams together did not provide a better agreement. The highest sensitivity and specificity (92 and 89%, respectively) were only attained when 2 exams suggested NC diagnosis, being CT one of them. These enabled us to suggest that 33 out of 48 (62.5%) patients had NC (evidenced in US+CT+KUB (81.8%), US+CT (12.1%) or KUB+CT (6.1%).

CONCLUSION

The low level of concordance renders the radiological diagnosis of NC difficult. Nephrocalcinosis should be confirmed by CT combined with either US or KUB.

Bilateral renal milk of calcium masquerading as nephrolithiasis in patients with spinal cord injury

Milk of calcium is a viscous colloidal suspension of calcium carbonate, calcium phosphate, or calcium oxalate, or a mixture of these compounds. The calcific material gravitates to the dependent portion of a cystic cavity. Crescent- or hemisphere-shaped calcium density with a sharp horizontal upper border at the milk of calcium-clear fluid interface confirms the diagnosis. Bilateral milk of calcium in the renal pelvis or in dilated calyces is very rare and has not been reported in patients with spinal cord injury. A 63-year-old male patient with T-10 paraplegia presented with recurrent urinary tract infections. X-ray of the kidneys, taken with the vertical beam while the patient lay supine, revealed a poorly defined opacity overlying the lower pole of the right kidney. Findings on ultrasonography of the kidneys were interpreted as a large, staghorn-type calculus in the dilated lower pole calyx of the right kidney. Because x-ray of the kidneys showed a poorly defined opacity overlying the lower pole of the right kidney, milk of calcium was suspected, and computed tomography (CT) of the kidneys was performed. Calcific debris with horizontal layering in the lower pole calyces of both kidneys was seen; this confirmed the diagnosis of milk of calcium. A 62-year-old female patient with C-7 tetraplegia underwent ileal conduit urinary diversion. Subsequently, she developed calculi in the right kidney, which were treated with shock wave lithotripsy. Follow-up x-ray revealed faintly opaque shadows with indistinct margins in the region of both kidneys. Intravenous urography showed cortical thinning at the upper poles and blunting of the calyces, suggestive of chronic pyelonephritis. The right renal pelvis was bulky, and bilateral renal calculi were diagnosed during ultrasonography; however, the presence of faintly radio-opaque shadows with indistinct margins raised suspicions of renal milk of calcium. A CT scan of the kidneys, which was performed in the supine and subsequently in the prone position, revealed gravity-dependent layering of calcific material in the pelves of both kidneys and in the midpole calyces of the right kidney, thus confirming the diagnosis of milk of calcium. In conclusion, CT scan of the kidneys confirmed the diagnosis of bilateral renal milk of calcium, a very rare entity in patients with spinal cord injury. Awareness of typical and unique features of milk of calcium during imaging enables physicians to recognize renal milk of calcium and to differentiate it from nephrolithiasis, thereby avoiding unwarranted interventions such as shock wave lithotripsy or endoscopic procedures.

Renal cortical nephrocalcinosis following acute renal failure due to polytrauma

Renal cortical nephrocalcinosis is a rare condition in which there is calcification within the renal parenchyma. This article reports a 33-year-old patient who developed acute renal failure following multiple injuries leading to hemorrhagic shock. His renal failure improved gradually, though he required dialysis support for two months. Serial ultrasounds showed a progressive decrease in renal size, and a radiograph of the abdomen showed speckled calcification in both renal areas. A CT scan of abdomen showed diffuse cortical calcification involving the entire right kidney and upper half of the left kidney.

Neonatal nephrocalcinosis: long term follow up

AIMS

To assess the spontaneous resolution of neonatal nephrocalcinosis and its long term effects on renal function.

METHODS

Fourteen very low birthweight preterm babies with nephrocalcinosis were followed up at 5-7 years of age; 14 controls were matched for sex, gestation, and birth weight. Height, weight, blood pressure, and renal symptomatology were recorded, and a renal ultrasound scan was performed. Early morning urine osmolality and creatinine ratios of albumin, phosphate, calcium, oxalate and beta microglobulin were determined. Urea and electrolytes in the study group were determined, and glomerular filtration rate (GFR) and TmP/GFR (tubular reabsorption of phosphate per GFR) were calculated. Statistical analysis was performed on a group basis using the Mann-Whitney confidence interval.

RESULTS

Mean age was 6.9 years (range 5.81-7.68). An early morning urine osmolality >700 mOsm/kg was achieved in all cases. In two cases and four controls, the calcium/creatinine ratio was >0.7 mmol/mmol. In all cases, the GFR was normal (median 132.6 ml/min/1.73 m(2) (range 104.1-173.1)). Median TmP/GFR was 1.22 mmol/l (0.73-1.61), with two having levels below the normal range. These did not have persisting nephrocalcinosis. Nephrocalcinosis was found in three of the 12 cases scanned and one control. There were no significant differences in urine biochemistry.

CONCLUSIONS

Resolution of nephrocalcinosis occurred in 75% of cases. No evidence was found to suggest that nephrocalcinosis is associated with renal dysfunction in the long term. There was evidence of hypercalciuria in the cases and controls, suggesting that prematurity may be a risk factor.

Resolution of medullary nephrocalcinosis in children with metabolic bone disorders

Ultrasonographic resolution of nephrocalcinosis (NC) has been reported in children with furosemide-induced NC, but not in other entities. We report the cases of four children with metabolic bone disease, two with hypophosphatasia and two with X-linked hypophosphatemic rickets, in whom we observed resolution of renal calcifications. At the time of ultrasonographic resolution of NC, 3 of the patients were on anticalciuric diuretics, and all 4 had normal urinalysis, serum creatinine and electrolyte profiles, as well as estimated creatinine clearance. In 3 of the children, evidence of mild tubular dysfunction was found. It thus seems that in some children with bone and mineral disorders who develop NC, ultrasonographic resolution of the renal calcifications can be seen; however, mild tubular dysfunction may remain and require follow-up. Further studies are suggested to explore the possible role of anticalciuric diuretics in promoting the resolution of NC.

Hypomagnesemia with hypercalciuria and nephrocalcinosis: case report and a family study

A 7-month-old male infant was referred for investigation after a documented febrile urinary tract infection. His past medical history was characterized by episodes of unexplained fever and mild dehydration. The ultrasound examination of his kidneys demonstrated bilateral diffuse medullary nephrocalcinosis. His serum and urine biochemistry revealed hypomagnesemia (0.4 mmol/l), hyperuricaemia (506 micromol/l), mildly increased iPTH (71 pg/ml) and hypercalciuria (16.0 mg/kg/day). The diagnosis of familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) was confirmed by mutational analysis of the CLDN16 gene, encoding paracellin-1. Sequencing displayed a homozygous Leu151Phe exchange affecting the first extracellular loop of paracellin-1. There were eight family relatives who underwent biochemical analysis, renal ultrasound and genetic investigation for CLDN16 mutations. Five of them were found to be heterozygous for the Leu151Phe mutation. Two heterozygotes (the mother and the maternal grandfather) presented with hypercalciuria. The grandfather had a history of recurrent passage of calculi. These findings point to the role of heterozygous CLDN16 gene mutations in renal pathophysiology. In conclusion, patients suspected of having FHHNC should be screened for CLDN16 mutations, especially with respect to genetic counseling. In addition, heterozygotes at risk should be clinically assessed in order to prevent renal complications of hypercalciuria.

Case report of a rare syndrome associating amelogenesis imperfecta and nephrocalcinosis in a consanguineous family

A rare syndrome associating amelogenesis imperfecta (AI) with nephrocalcinosis has been reported. The purpose of this study is to characterise the phenotype of a consanguineous family presenting amelogenesis imperfecta, delayed permanent teeth eruption and nephrocalcinosis. Six family members were examined. Ground sections of the case index deciduous teeth and biopsies of enlarged dental follicles were analysed. The patients's parents were first cousins. The case index had yellow discoloration and altered teeth shapes, retention of deciduous teeth, and delayed eruption. Panoramic radiographs revealed multiple enlarged pericoronal follicles in unerupted teeth and generalised intrapulpal calcifications. Renal ultrasound showed the presence of nephrocalcinosis. No other family members presented enamel defects or nephrocalcinosis. Histologically, the enamel appeared hypoplastic, and dental follicles indicated pericoronal hamartoma. The consanguineous marriage suggests an autosomal recessive mode of inheritance. Further studies are necessary to clarify the genetic defect behind this syndrome that associates AI, nephrocalcinosis and impaired tooth eruption.

A case report and review of hypokalemic paralysis secondary to renal tubular acidosis

A 5-year-old girl with distal renal tubular acidosis (RTA) and hypokalemic muscle paralysis is reported. RTA is a known cause of hypokalemia, but in spite of the presence of persistent hypokalemia muscular paralysis is uncommon, rarely described in children, and the onset of paralysis may initially be misinterpreted particularly if the patient is attended by a physician who is not a pediatric nephrologist. Therefore parents must be informed about this possibility. Still, as the clinical appearance of hypokalemic paralysis is quite similar to familial hypokalemic periodic paralysis, and because the emergent and prophylactic treatment of the two disorders are quite different, we discuss the diagnostic evaluation and the treatment for both of them.

Nephrocalcinosis in very low birth weight infants: a single center experience

OBJECTIVES

To determine the incidence and risk factors of nephrocalcinosis in very low birth weight infants.

MATERIAL AND METHOD

Medical records of inborn infants with gestational age less than 32 weeks or birth weight less than 1,250 grams were collected and analyzed. All infants were born at King Chulalongkorn Memorial Hospital in the year 2003. At least one renal ultrasonographic scan was performed on every infant as a routine screening before discharge. Data on family history of renal stone, gestational age, birthweight, infant's illness,fluid intake during the first 6 weeks of life, duration of respiratory support, medications, serum calcium, phosphate and alkaline phosphatase level, duration of parenteral nutrition, length of hospitalization, ultrasonographic findings and related renal morbidity were collected and compared between the groups of infants with and without nephrocalcinosis.

RESULTS

Thirty six infants were included in the present study. Fourteen had abnormal ultrasound scans compatible with nephrocalcinosis giving an overall incidence of 38.9%. Factors associated with nephrocalcinosis included severity of respiratory illness, PDA, oxygen dependency, furosemide therapy, and fluid restriction. Urinary tract infection was the renal morbidity found in 3 infants (21.4%). Nephrocalcinosis was resolved in one out of 7 infants who had repeated renal ultrasound scan at about 2 months after the first scan.

CONCLUSION

Very low birth weight, preterm infants have a risk of developing nephrocalcinosis especially those with severe respiratory illness and prolonged use of furosemide. Infants at risk should be screened with renal ultrasonography prior to discharge from the hospital.

Development of nephrocalcinosis in very low birth weight infants

Premature infants undergo intensive growth during the postnatal period. Adequate mineralization is dependent on sufficient intake of calcium (Ca) and phosphorus (P). However, Ca and P supplementation can be associated with some risks, for example development of nephrocalcinosis. We investigated pathophysiological risk factors in premature very low birth weight (VLBW) infants associated with the development of nephrocalcinosis. From June 1994 to September 1995 all preterm neonates with a birth weight below 1,500 g were screened prospectively. At regular intervals of 2 weeks, ultrasonography (US) of the kidneys was performed and parameters of mineral metabolism were assessed in blood and spot urine samples. For analysis, premature infants with nephrocalcinosis (group N) were compared with infants without nephrocalcinosis (group R) and with a retrospectively pair-matched subgroup of premature infants without nephrocalcinosis (control group C) taken from the same study. Nephrocalcinosis was detected in 20 of 114 preterm neonates (group N, 17.5%). Of these 20 infants with nephrocalcinosis, 16 presented with a tendency towards systemic acidosis (pH<7.25) on day 2-7, compared with only 4 of 20 premature infants of the control group. Premature infants of group N had a lower serum P at 2 weeks of life and 5 (versus 0 patients of the control group C) had transient hypophosphatemia (serum P<1.6 mmol/l). Moreover, the Ca/creatinine ratio in spot urine specimens tended to be higher (P<0.1) in patients developing nephrocalcinosis. There were no significant differences in the duration of ventilation, the length of stay in the intensive care unit, and duration and frequency of furosemide and steroid treatment between the groups N and C. VLBW premature infants developing nephrocalcinosis frequently presented with slightly impaired acid-base homoeostasis within the 1st week, followed by signs of impaired mineralization (and immature or impaired renal function) within 2 weeks. In VLBW premature infants, close observation of acid-base status and regular analysis of spot urine specimens (Ca, P, creatinine) during the first weeks of life may help to identify those premature infants at risk for nephrocalcinosis.