Clinical practice: proteinuria

Adapting Clinical Practice Guidelines for Chronic Kidney Disease: Blood Pressure Management and Kidney Replacement Therapy in Adults and Children in the Saudi Arabian Context Using the Grading of Recommendations Assessment, Development, and Evaluation-ADOLOPMENT Methodology

This practice guideline was developed by the chronic kidney disease (CKD) Task Force, which was composed of clinical and methodological experts. The Saudi Arabian Ministry of Health and its health holding company commissioned this guideline project to support the realization of Vision 2030's health-care transformation pillar. The synthesis of these guidelines was guided by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE)- ADOLOPMENT methodology. The final guidelines addressed 12 clinical questions on the management of blood pressure in patients with CKD through a set of recommen-dations and performance measures. The recom-mendations included antihypertensive agents in children; renin- angiotensin system inhibition (RASi) versus non-RASi in adults; intensive versus standard blood pressure targets; early versus late assessment for kidney replacement therapy (KRT); late versus early preparation strategies for KRT; CKD symptoms during assessment for KRT or conservative manage-ment; initiation of KRT in patients with deteriorating CKD; choice of KRT modality or conservative management in certain CKD patient groups; changing or discontinuing KRT modalities; the frequency of reviews for KRT or conservative management; and information, education, and support. These conditional recommendations were based on a low to very low certainty of evidence, which highlights the need for high-quality randomized trials com-paring different antihypertensive agents in patients with CKD.

Acute kidney injury in children with haematological malignancy: a territory-wide study

BACKGROUND

In onco-nephrology, data on acute kidney injury (AKI) among children with haematological malignancies are scarce.

METHODS

A retrospective cohort study of all patients in Hong Kong diagnosed with haematological malignancies from 2019 to 2021 before 18 years of age, was conducted to investigate the epidemiology, risk factors and clinical outcomes of AKI during the first year of treatment. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria.

RESULTS

We included 130 children with haematological malignancy at median age of 9.4 years (IQR, 3.9-14.1). Of these patients, 55.4% were acute lymphoblastic leukemia (ALL), 26.9% were lymphoma and 17.7% were acute myeloid leukemia (AML). Thirty-five patients (26.9%) developed 41 AKI episodes during the first year of diagnosis, corresponding to 32 episodes per 100-patient-year. A total of 56.1% and 29.2% of the AKI episodes occurred during induction and consolidation chemotherapy respectively. Septic shock (n = 12, 29.2%) was the leading cause of AKI; 21 episodes (51.2%) were stage 3 AKI; 12 episodes (29.3%) were stage 2 AKI; and 6 patients required continuous kidney replacement therapies. Tumor lysis syndrome and impaired baseline kidney function were significantly associated with AKI on multivariate analysis (P = 0.01). History of AKI was associated with chemotherapy postponement (37.1% vs. 16.8%, P = 0.01), worse 12-month patient survival (77.1% vs. 94.7%, log rank P = 0.002) and lower disease remission rate at 12-month (68.6% vs. 88.4%, P = 0.007), compared to patients without AKI.

CONCLUSION

AKI is a common complication during treatment of haematological malignancies which is associated with worse treatment outcomes. A regular and dedicated surveillance program for at-risk patients should be studied in children with haematological malignancies for prevention and early detection of AKI. A higher resolution version of the Graphical abstract is available as Supplementary information.

Evaluation of urinary haptoglobin level as a biomarker of diabetic nephropathy in children with type 1 diabetes

BACKGROUND

Type 1 diabetes mellitus (T1DM) is a common endocrine disease in children. Early recognition of complications of T1DM is important for preventing long-term morbidity and mortality. We aimed to investigate whether urinary haptoglobin level is a biomarker of diabetic nephropathy in children with T1DM.

METHODS

Ninety T1DM patients, aged between 2-18 years, and 60 healthy age-matched children were included in the study. Glycosylated hemoglobin (HbA1c), spot urine creatinine, microalbumin, protein and haptoglobin levels of all cases were measured and compared. Correlations between HbA1c level, duration of diabetes, spot urine microalbumin/creatinine (uACR), protein/creatinine (uPCR), and haptoglobin/creatinine (uHCR) ratios in the T1DM group were evaluated.

RESULTS

T1DM and control groups were homogeneous in terms of age, sex, and anthropometric measurements. uACR was higher in the T1DM group than in the control group (14 mg/g vs. 6 mg/g) while uHCR was not elevated in T1DM patients. Nevertheless, uHCR was higher in the microalbuminuria group when compared to the normoalbuminuria group. In the T1DM group, moderate positive correlations between uPCR with uACR and uHCR, and weak correlation between uACR and uHCR were found (r = 0.60, p < 0.001; r = 0.55, p < 0.001; r = 0.24, p = 0.03, respectively). No significant relationship was found between diabetes duration, HbA1c levels and uACR, uPCR, and uHCR.

CONCLUSIONS

Although uHCR in the T1DM group was similar to the control group, uHCR was higher in the microalbuminuria group than in the normoalbuminuria group. These results show that the uHg level could be a biomarker of diabetic nephropathy, but not earlier than albuminuria in the disease course. A higher resolution version of the Graphical abstract is available as Supplementary information.

How to define and assess the clinically significant causes of hematuria in childhood

Given the wide diversity of causes of hematuria, ranging from simple urinary tract infections with rapid recovery to severe glomerulonephritis with fast decline in kidney function, it is essential to recognize the underlying disease. The first objective of the assessment is to determine whether the cause of the hematuria is medically significant. The combination of hematuria with proteinuria, the presence of hypertension, or worsening kidney function can represent signs of progressive kidney disease. Differentiating the various causes of hematuria is often simple and obvious based on the clinical signs and gross appearance of the urine. However, in some instances, additional non-invasive investigations, such as ultrasound imaging, urinary red cell morphology, measurement of calcium and other solutes in the urine, evaluation of kidney function, and protein excretion, are needed to elucidate the nature of the hematuria. Taking a detailed family history can help in establishing the underlying cause in cases of familial hematuria. On the other hand, the decision to perform a kidney biopsy in children with asymptomatic hematuria remains a challenging issue for clinicians. Ultimately, the frequency of diagnosis of glomerular involvement causing hematuria may depend on the threshold for performing a kidney biopsy. The following review will focus on the diagnostics of hematuria, starting with difficulties regarding its definition, followed by various means to differentiate between urinary, glomerular, and other causes, and finally reviewing the most common diseases that, due to their frequency or their effect on kidney function, present a diagnostic challenge in everyday practice.

The importance of ambulatory blood pressure monitoring for diagnosing masked hypertension in patients with renal parenchymal scarring

BACKGROUND

The most well-known and common long-term complication in children with renal parenchymal scarring (RPS) is hypertension (HT). The present study aimed to evaluate the presence of HT in children with RPS based on ambulatory blood pressure monitoring (ABPM) and to compare the patients' blood pressure (BP) to that in healthy controls matched for age, gender, and BMI.

METHODS

The study included 55 patients aged < 18 years diagnosed with RPS who were followed up for ≥ 1 year and 48 healthy controls matched for age, gender, and BMI.

RESULTS

Mean age in the RPS group was 12.8 ± 3.3 years, and 49.1% of the group were female. Among the RPS patients, 28 were diagnosed with HT based on ABPM, of which 18 (32.7%) had an office BP < 90th percentile for age, gender, and height; seven had an office BP between the 90-95th percentiles for age, gender, and height; and three had an office BP > 95 percentile for age, gender, and height. The difference in detection of HT based on ABPM between the two groups was significant (P = 0.00).

CONCLUSIONS

Early diagnosis of HT via ABPM can help prevent development of kidney failure and cardiovascular disease in patients with RPS, significantly reducing the rates of morbidity and mortality. All children with RPS should be evaluated via ABPM, even if office BP measurements are normal. "A higher resolution version of the Graphical abstract is available as Supplementary information".

Clinical and genetic characterization of a cohort of proteinuric patients with biallelic CUBN variants

BACKGROUND

Proteinuria is a well-known risk factor for progressive kidney impairment. Recently, C-terminal cubilin (CUBN) variants have been associated with isolated proteinuria without progression of kidney disease.

METHODS

Genetic testing of 347 families with proteinuria of suspected monogenic cause was performed by next-generation sequencing of a custom-designed kidney disease gene panel. Families with CUBN biallelic proteinuria-causing variants were studied at the clinical, genetic, laboratory, and pathologic levels.

RESULTS

Twelve families (15 patients) bearing homozygous or compound heterozygous proteinuria-causing variants in the C-terminal CUBN gene were identified, representing 3.5% of the total cohort. We identified 14 different sequence variants, five of which were novel. The median age at diagnosis of proteinuria was 4 years (range 9 months to 44 years), and in most cases proteinuria was detected incidentally. Thirteen patients had moderate-severe proteinuria at diagnosis without nephrotic syndrome. These patients showed lack of response to angiotensin-converting enzyme inhibitor (ACEi) and angiotensin receptor blocker (ARB) treatment, normal kidney biopsy, and preservation of normal kidney function over time. The two remaining patients presented a more severe phenotype, likely caused by associated comorbidities.

CONCLUSIONS

Identification of C-terminal pathogenic CUBN variants is diagnostic of an entity characterized by glomerular proteinuria, normal kidney histology, and lack of response to ACEi/ARB treatment. This study adds evidence and increases awareness about albuminuria caused by C-terminal variants in the CUBN gene, which is a benign condition usually diagnosed in childhood with preserved renal function until adulthood.

Retrospective evaluation of children with unilateral renal agenesis

BACKGROUND

Children born with unilateral renal agenesis (URA) are thought to have a risk of developing hypertension, proteinuria, and progressive chronic kidney disease (CKD). The present study aimed to evaluate the long-term prognosis and clinical characteristics of children with URA.

METHODS

The study included 171 patients aged < 18 years diagnosed as URA who were followed-up for ≥ 1 year and 121 healthy controls matched for age, gender, and BMI.

RESULTS

Median age at diagnosis was 2 years (IQR: 1 month-16 years) and the incidence of URA in males (65.4%) was higher than in females. Among the patients, 21 (12.2%) had other urinary system anomalies. It was noted that 2.3% of the patients had proteinuria, 15.2% had hyperfiltration, and 2.9% had CKD. Hypertension based on ambulatory blood pressure monitoring (ABPM) was diagnosed in 18 (10.5%) of the patients, of whom 10 had masked hypertension. Diastolic blood pressure in the URA patients was significantly higher than in the healthy controls. The incidence of hypertension and CKD was significantly higher in the patients with other urinary system anomalies.

CONCLUSIONS

Patients with a single functional kidney should be periodically evaluated throughout their lifetime for urine protein, blood pressure, and kidney functions. The most remarkable finding of this study is the importance of the use of ABPM for evaluating blood pressure in pediatric URA patients, especially for the detection of masked hypertension and the non-dipper phenomenon, which cannot be achieved with office blood pressure measurement.

Enhanced MCP-1 Release in Early Autosomal Dominant Polycystic Kidney Disease

Introduction

Autosomal dominant polycystic kidney disease (ADPKD) causes kidney failure typically in adulthood, but the disease starts in utero. Copeptin, epidermal growth factor (EGF), and monocyte chemoattractant protein-1 (MCP-1) are associated with severity and hold prognostic value in adults but remain unstudied in the early disease stage. Kidneys from adults with ADPKD exhibit macrophage infiltration, and a prominent role of MCP-1 secretion by tubular epithelial cells is suggested from rodent models.

Methods

In a cross-sectional study, plasma copeptin, urinary EGF, and urinary MCP-1 were evaluated in a pediatric ADPKD cohort and compared with age-, sex-, and body mass index (BMI)-matched healthy controls. MCP-1 was studied in mouse collecting duct cells, human proximal tubular cells, and fetal kidney tissue.

Results

Fifty-three genotyped ADPKD patients and 53 controls were included. The mean (SD) age was 10.4 (5.9) versus 10.5 (6.1) years (P = 0.543), and the estimated glomerular filtration rate (eGFR) was 122.7 (39.8) versus 114.5 (23.1) ml/min per 1.73 m² (P = 0.177) in patients versus controls, respectively. Plasma copeptin and EGF secretion were comparable between groups. The median (interquartile range) urinary MCP-1 (pg/mg creatinine) was significantly higher in ADPKD patients (185.4 [213.8]) compared with controls (154.7 [98.0], P = 0.010). Human proximal tubular cells with a heterozygous PKD1 mutation and mouse collecting duct cells with a PKD1 knockout exhibited increased MCP-1 secretion. Human fetal ADPKD kidneys displayed prominent MCP-1 immunoreactivity and M2 macrophage infiltration.

Conclusion

An increase in tubular MCP-1 secretion is an early event in ADPKD. MCP-1 is an early disease severity marker and a potential treatment target.

Are My Pediatric Patients at Increased Risk of Developing Chronic Kidney Disease?

Chronic kidney disease (CKD) is an underrecognized and often undiagnosed cause of morbidity and mortality. Many children and adolescents are at increased risk of developing CKD as they mature and age, secondary to conditions commonly cared for by pediatric health professionals. Prematurity, diabetes mellitus, hypertension, congenital heart disease, sickle cell disease and trait, severe obesity, cancer chemotherapy, other drug toxicities, and systemic situations that may cause acute kidney injury such as sepsis or extracorporeal membrane oxygenation therapy predispose to potential CKD. Clinicians should be aware of these conditions in order to screen for CKD, choose non-nephrotoxic treatments for these children whenever possible, and treat or refer those who have early signs of CKD.

Persistent Abnormalities of Fatty Acids Profile in Children With Idiopathic Nephrotic Syndrome in Stable Remission

Steroid-sensitive nephrotic syndrome is an immunological disorder mediated by still poorly defined circulating factor(s) that target the podocyte and damage the filtration barrier. Fatty acids (FA) have several biological roles and, in particular, are strictly involved in cell to cell communication, inflammatory processes and regulation of lymphocyte pools. Studies of FAs during INS have been mainly focused on biochemical changes during the phase of proteinuria; while no information is available about FA profile in patients with idiopathic nephrotic syndrome (INS) on stable remission. Aim of this study is to assess differences in blood FA profile between pediatric patients with INS during the phase of stable remission. Blood fatty acid profile of 47 pediatric patients on stable remission and 47 matched healthy controls were evaluated with gas chromatography. Patients with INS on stable remission had significantly higher levels of PUFA and omega-6 than controls (40.17 vs. 37.91% and 36.95 vs. 34.79%), lower levels of SFA and MUFA. Considering the single fatty acids, levels of omega-6 18:2n6 linoleic acid and omega-6 20:4n6 arachidonic acid were significantly higher in patients with INS than in controls (23.01 vs. 21.55%, p-value 0.003 and 10.37 vs. 9.65%, p-value 0.01). Moreover, patients with INS showed lower levels of SFA 14:0 (0.74 vs. 0.92%) and 18:0 (10.74 vs. 11.74%) and MUFA 18:1n9 oleic acid (18.50 vs. 19.83%). To the best of our knowledge this is the first study assessing FAs profile in children with INS in stable remission. In a population of 47 patients, we were able to demonstrate a higher blood level of linoleic and arachidonic acid, and consequently of omega-6 and PUFA, compared to controls. Persistently higher than normal levels of either linoleic or arachidonic acid, could be viewed as candidate biomarker for a state of risk of relapse in children with idiopathic nephrotic syndrome.

Simplified Algorithm for Evaluation of Proteinuria in Clinical Practice: How should A Clinician Approach?

Background

Proteinuria is a common laboratory finding among children and adolescents. It can be identified as either a transient or a persistent finding and can represent a benign condition or a serious disease.

Methods

Pertinent medical literature for asymptomatic proteinuria in children and adolescents published in English was searched between January 1980 and May 2017 using PubMed, MEDLINE, EMBASE, and Google Scholar research databases. Of the 64 reviewed articles, 24 studies were eligible for inclusion.

Results

Random spot urine protein-to-creatinine (PCR) ratio is widely used to reliably detect proteinuria. The normal value for the spot PCR in children aged 2 years or older is less than 0.3. In children aged below 2 years, the PCR can be as high as 0.5. Orthostatic proteinuria is defined as urine PCR greater than 0.3 detected in a urine specimen during the daytime activity but less than 0.3 on the first morning void specimen. PCR above 3.0 signifies heavy proteinuria as seen in nephrotic syndrome. Orthostatic proteinuria is a frequent cause of proteinuria in asymptomatic children and adolescents, which require no specific therapy except for health maintenance follow-up. Pediatric nephrologist referral is indicated when the proteinuria is constant and persists over 6 months or is associated with hematuria, hypertension, or renal dysfunction.

Conclusions

We provide a simplified diagnostic algorithm for evaluation of proteinuria in primary care adolescents who appear well and in whom proteinuria is incidentally discovered during a routine examination.

Urinary stone risk factors in the descendants of patients with kidney stone disease

BACKGROUND

Evidence has indicated that immediate family members of nephrolithiasis patients had high opportunity to develop stones. However, they are usually not regarded to be at risk, since it is unclear if there are any lithogenic abnormalities found in non-stone-forming nephrolithiasis relatives. Our aim was to investigate urinary metabolic abnormalities in the children of nephrolithiasis patients, compared with the general population.

METHODS

The 24-h urinary metabolic profile was studied for 28 calcium oxalate nephrolithiasis patients (NL) and 46 of their descendants (ND), as well as 40 non-stone-forming volunteers (V) and 34 of their descendants (VD).

RESULTS

There was no difference between age, gender, and serum creatinine between NL vs. V (parental groups) and ND vs. VD (descendant groups). High urinary oxalate in nephrolithiasis and urinary calcium in their descendants was detected. In addition, an elevated urinary excretion rate of calcium, phosphate, protein, and albumin, along with low citrate excretion and high urinary supersaturation was observed in both the nephrolithiasis patients and their descendants. Approximate 17.8-24.4% of the nephrolithiasis descendants had a urinary supersaturation higher than the nephrolithiasis level, but none was found in VD group. The level of urinary supersaturation index was correlated with urinary protein and albumin excretion in nephrolithiasis family.

CONCLUSION

It was demonstrated that nephrolithiasis offspring carried several urinary metabolic risks predisposing to stone formation which are similar to their parents, and about one in every five nephrolithiasis children had nephrolithiasis level urinary supersaturation.

Longitudinal Study of the Role of Epidermal Growth Factor on the Fractional Excretion of Magnesium in Children: Effect of Calcineurin Inhibitors

BACKGROUND

It was shown in animal models and adults that the epidermal growth factor (EGF) is involved in the pathophysiology of calcineurin inhibitor (CNI) induced renal magnesium loss. In children, however, the exact mechanism remains unclear, which was set as the purpose of the present study.

METHODS

Children with nephrotic syndrome and renal transplant children treated with CNI (n = 50) and non-CNI treated children (n = 46) were included in this study. Urine and serum samples were collected at three time points to determine magnesium, creatinine, and EGF. The magnesium intake was calculated from a food frequency questionnaire.

RESULTS

Serum Mg²⁺ and urinary EGF/creatinine were significantly lower in the CNI treated children, with significantly more CNI-treated children developing hypomagnesaemia. In the latter patients, the fractional excretion of magnesium (FE Mg²⁺) was significantly higher. Urinary EGF, age, renal function, and serum magnesium were independent predictors of the FE Mg²⁺. Only 29% of the children reached the recommended daily intake of magnesium. The magnesium intake did not differ between hypomagnesemic and normomagnesemic patients and was not a predictor of the FE Mg²⁺.

CONCLUSIONS

In CNI-treated children who developed hypomagnesemia, the FE Mg²⁺ was increased. The urinary EGF concentration, age, and renal function are independent predictors of the FE Mg²⁺.

Highlights for the management of a child with proteinuria and hematuria

The identification of hematuria or proteinuria in an otherwise healthy child can cause anxiety to both the family and the pediatrician. The etiology of hematuria and proteinuria includes a long list of conditions, and detailed workup can be exhaustive, expensive and not essential in most of the patients. As will be described in this paper, most of the children with proteinuria or hematuria have a benign etiology. The primary role of the pediatrician is to identify hematuria/proteinuria, recognize the common causes of hematuria/proteinuria, and more importantly identify children with serious conditions that need referral to the nephrologist in a timely manner.

Acute hemorrhagic edema of young children: a concise narrative review

Acute hemorrhagic edema of young children is an uncommon but likely underestimated cutaneous leukocytoclastic vasculitis. The condition typically affects infants 6-24 months of age with a history of recent respiratory illness with or without course of antibiotics. The diagnosis is made in children, mostly nontoxic in appearance, presenting with nonpruritic, large, round, red to purpuric plaques predominantly over the cheeks, ears, and extremities, with relative sparing of the trunk, often with a target-like appearance, and edema of the distal extremities, ears, and face that is mostly non-pitting, indurative, and tender. In boys, the lesions sometimes involve the scrotum and, more rarely, the penis. Fever, typically of low grade, is often present. Involvement of body systems other than skin is uncommon, and spontaneous recovery usually occurs within 6-21 days without sequelae. In this condition, laboratory tests are non-contributory: total blood cell count is often normal, although leukocytosis and thrombocytosis are sometimes found, clotting studies are normal, erythrocyte sedimentation rate and C-reactive protein test are normal or slightly elevated, complement level is normal, autoantibodies are absent, and urinalysis is usually normal. Experienced physicians rapidly consider the possible diagnosis of acute hemorrhagic edema when presented with a nontoxic young child having large targetoid purpuric lesions and indurative swelling, which is non-pitting in character, and make the diagnosis either on the basis of clinical findings alone or supported by a skin biopsy study.

Massive proteinuria: a possible side effect of pyrantel pamoate?

Drug-induced renal injury represents a frequent clinical entity. The most common drugs associated with acute tubular necrosis are aminoglycosides, amphotericin B, radiocontrast agents, and cyclosporine, but no data exist about the potential renal toxicity due to anthelmintics administration. Anthelmintics are commonly considered quite safe agents, and side effects such as gastrointestinal, neurologic, hematologic, or hepatic injury have been only rarely described. We report a 4-year-old boy with persistent massive proteinuria without any other symptoms/signs suggesting nephrotic syndrome (NS). The only relevant anamnestic data was the administration of pyrantel pamoate due to oxyuriasis 7 days before the proteinuria development. The patient was affected by NS diagnosed 6 months before and treated with a 12-week course of corticosteroids. During follow-up, carried out at 3 and 6 months after discharge, he did not show further episodes of proteinuria, and no clinical symptoms/signs suggesting a relapse of NS were ever detected. Considering that the proteinuria observed in our patient spontaneously disappeared after 10 days without any treatment, apart from the interruption of the anthelmintic therapy, we would like to alert pediatricians about the possible occurrence of anthelmintics-related renal complications especially among predisposed patients and to perform a watchful waiting not considering the presence of even massive proteinuria as a certain sign of NS relapse.