Congenital nephrotic syndrome—a treatable cause

Clinical characteristics of infants hospitalized with early congenital syphilitic nephropathy: a single-center retrospective cross-sectional study in China

BACKGROUND

Early studies claimed that early congenital syphilitic (CS) nephropathy was rare, and systematic studies about this disease are absent, which may lead to poor awareness of early CS nephropathy in clinicians and result in misdiagnosis and poor patient prognosis. The present study systematically and comprehensively analyzes the clinical characteristics of infants with early CS nephropathy hospitalized in Beijing Ditan Hospital, an infectious disease hospital in China in order to improve the understanding and management of this disorder.

METHODS

Data of the children with early CS from July 1, 2008, to December 31, 2021, were collected from the electronic medical record system of the hospital. Each patient's demographic characteristics, clinical history, mother's history of syphilitic infection, and laboratory values were extracted. The patients were enrolled to either the nephropathy group or the non-nephropathy group depending on diagnosis. Descriptive statistics was used to report basic demographics, clinical and laboratory test values, and variables were compared between the two groups by nonparametric tests, t test or χ2 tests.

RESULTS

Of the 122 children with early CS enrolled, 24(19.7%) were diagnosed with early CS nephropathy. All of the children with CS nephropathy were young infants < 6 months old. A majority of them showed typical congenital syphilitic skin lesions, but a quarter of them did not have skin lesions. Compared with non-nephropathic children with early CS, those with nephropathy had higher frequency of hepatosplenomegaly, fever, edema, gastrointestinal (GI) symptoms, and anemia, as well as decreased C3 levels. Urinalysis results showed hematuria in all patients with early CS nephropathy, with proteinuria and renal function impairment in 91.7% and 12.5% of the patients, respectively. Nephritic-type nephrotic syndrome and glomerulonephritis were diagnosed in 45.8% and 54.2% of these patients, respectively. All infants with CS nephropathy were cured or improved after appropriate treatments.

CONCLUSION

Infants with early CS nephropathy often presented with nephritic-type nephrotic syndrome or glomerulonephritis, and the typical skin lesions, fever, hepatosplenomegaly, and edema, etc., were its common clinical presentations, and these characteristics could help with the diagnosis. But for infants with nephropathy who did not have typical clinical presentations, CS should also be screened as an important etiology to avoid misdiagnosis.

Congenital nephrotic syndrome

Congenital nephrotic syndrome (CNS), a challenging form of nephrotic syndrome, is characterized by massive proteinuria, hypoalbuminemia, and edema. Extensive leakage of plasma proteins is the main feature of CNS. Patients can be diagnosed in utero or during the first few weeks of life, usually before three months. The etiology of CNS can be related to either genetic or nongenetic etiologies. Pathogenic variants in NPHS1, NPHS2, LAMB2, WT1, and PLCE1 genes have been implicated in this disease. The clinical course is complicated by significant edema, infections, thrombosis, hypothyroidism, failure to thrive, and others. Obtaining vascular access, frequent intravenous albumin infusions, diuretic use, infection prevention, and nutritional support are the mainstay management during their first month of life. The best therapy for these patients is kidney transplantation. CNS diagnosis and treatment continue to be a challenge for clinicians. This review increases the awareness about the pathogenesis, diagnosis, and management of CNS patients.

Nephrotic syndrome in infants and children: pathophysiology and management

Nephrotic syndrome is defined by nephrotic-range proteinuria (≥40 mg/m²/hour or urine protein/creatinine ratio ≥200 mg/mL or 3+ protein on urine dipstick), hypoalbuminaemia (<25 g/L) and oedema. This review focuses on the classification, epidemiology, pathophysiology, management strategies and prognosis of idiopathic nephrotic syndrome of childhood, and includes a brief overview of the congenital forms.

Nephrotic and nephritic syndrome in the newborn

Glomerular disorders in infancy can include nephrotic and nephritic syndromes. Congenital nephrotic syndrome (CNS) is most commonly caused by single gene mutations in kidney proteins, but may also be due to congenital infections or passive transfer of maternal antibodies that target kidney proteins. Prenatal findings of increased maternal serum α-fetoprotein and enlarged placenta suggest CNS. Neonatal nephritis is rare; its causes may overlap with those of CNS and include primary glomerulonephritis, systemic disease, infections, and transplacental transfer of maternal antibodies. These syndromes in the neonate can cause significant morbidity and mortality, making urgent diagnosis and treatment necessary.

An unusual cause of membranous glomerulonephritis in a patient with HIV

A 68-year old Caucasian male with a past medical history of human immunodeficiency virus (HIV) infection presented with acute oliguric renal failure and maculopapular rash. Renal biopsy demonstrated extensive foot process effacement as well as confluent small subepithelial electron-dense deposits, which is diagnostic of membranous glomerulonephritis. Subsequent serological tests showed venereal disease research laboratory test was positive in both serum and cerebral spinal fluid. Following penicillin treatment, the patient's creatinine returned to baseline 4 weeks later. Secondary membranous glomerulonephritis caused by syphilis in patients with HIV is discussed.