Occurrence of renal fanconi syndrome in children on valproic acid therapy

Kidney tubular injury induced by valproic acid: systematic literature review

BACKGROUND

Valproic acid is prescribed for epilepsy and as prophylaxis for bipolar disorder and migraine headaches. It has also been implicated as a cause of a kidney tubular injury.

METHODS

We undertook a review of the literature to characterize the biochemical and histopathological features of the overt kidney tubular injury and to evaluate the possible existence of a pauci-symptomatic injury. The pre-registered review (CRD42022360357) was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Searches were conducted in Excerpta Medica, the National Library of Medicine, and Web of Science. The gray literature was also considered.

RESULTS

For the final analysis, we retained 36 articles: 28 case reports documented 48 individuals with epilepsy on valproic acid for 7 months or more and presenting with features consistent with an overt kidney tubular injury. The following disturbances were noted: hypophosphatemia (N = 46), normoglycemic glycosuria (N = 46), total proteinuria (N = 45), metabolic acidosis (N = 36), hypouricemia (N = 27), tubular proteinuria (N = 27), hypokalemia (N = 23), and hypocalcemia (N = 8). A biopsy, obtained in six cases, disclosed altered proximal tubular cells with giant and dysmorphic mitochondria. Eight case series addressed the existence of a pauci- or even asymptomatic kidney injury. In the reported 285 subjects on valproic acid for 7 months or more, an isolated tubular proteinuria, mostly N-acetyl-β-glucosaminidase, was often noted.

CONCLUSIONS

Valproic acid may induce an overt kidney tubular injury, which is associated with a proximal tubular mitochondrial toxicity. Treatment for 7 months or more is often associated with a pauci- or oligosymptomatic kidney tubular injury. A higher resolution version of the Graphical abstract is available as Supplementary information.

Mechanism of valproic acid-induced Fanconi syndrome involves mitochondrial dysfunction and oxidative stress in rat kidney

AIM

Drug-induced kidney proximal tubular injury and renal failure (Fanconi syndrome; FS) is a clinical complication. Valproic acid (VPA) is among the FS-inducing drugs. The current investigation was designed to evaluate the role of mitochondrial dysfunction and oxidative stress in VPA-induced renal injury.

METHODS

Animals received VPA (250 and 500 mg/kg, i.p., 15 consecutive days). Serum biomarkers of kidney injury and markers of oxidative stress were assessed. Moreover, kidney mitochondria were isolated and mitochondrial indices, including succinate dehydrogenase activity (SDA), mitochondrial depolarization, mitochondrial permeability transition pore (MPP), reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial glutathione, and ATP were determined.

RESULTS

Valproic acid-treated animals developed biochemical evidence of FS as judged by elevated serum gamma-glutamyl transferase (γ-GT), alkaline phosphatase (ALP), creatinine (Cr), and blood urea nitrogen (BUN) along with hypokalaemia, hypophosphataemia, and a decrease in serum uric acid. VPA caused an increase in kidney ROS and LPO. Renal GSH reservoirs were depleted and tissue antioxidant capacity decreased in VPA-treated animals. Renal tubular interstitial nephritis, tissue necrosis, and atrophy were also evident in VPA-treated rats. Mitochondrial parameters including SDA, MMP, GSH, ATP and MPP were decreased and mitochondrial ROS and LPO were increased with VPA treatment. It was found that carnitine (100 mg/kg, i.p.) mitigated VPA adverse effects towards the kidney.

CONCLUSIONS

These data suggest that mitochondrial dysfunction and oxidative stress contributed to the VPA-induced FS. On the other hand, carnitine could be considered a potentially safe and effective therapeutic option in attenuating VPA-induced renal injury.

The effects of sodium valproate on the renal function of children with epilepsy

Sodium valproate is one of the most commonly used drugs to treat epilepsy. However, there is growing evidence that valproate can cause renal tubular injury in children, and there are increasing reports of valproate-induced Fanconi's syndrome where the renal tubules lose their ability to reabsorb electrolytes, urea, glucose and protein. In this review article we attempt to bring together all of the studies conducted to date on the effects of valproate on renal function in epileptic children. The research is generally considered in two themes; the first comprises studies which indicate subclinical tubular injury measured by renal enzymes such as N-acetyl-β-D-glucosaminidase (NAG), and the second comprises clinical reports where Fanconi's syndrome has occurred. This article goes on to analyse the current data and draws on recurring patterns to suggest that a specific subpopulation of severely disabled epileptic children may benefit hugely from the close monitoring of enzymes which are indicative of renal tubular injury, particularly NAG or in the very least periodical urinalysis.

Verbal memory in mesial temporal lobe epilepsy: beyond material specificity

The idea that verbal and non-verbal forms of memory are segregated in their entirety, and localized to the left and right hippocampi, is arguably the most influential concept in the neuropsychology of temporal lobe epilepsy, forming a cornerstone of pre-surgical decision making, and a frame for interpreting postoperative outcome. This critical review begins by examining some of the unexpressed but inescapable assumptions of the material-specificity model: (i) verbal and non-verbal memory are unitary and internally homogenous constructs; and (ii) left and right memory systems are assumed to be independent, self-contained modules. The next section traces the origins of an alternative view, emanating largely from three challenges to these assumptions: (i) verbal memory is systematically fractionated by left mesial temporal foci; (ii) the resulting components are differentially localized within the left temporal lobe; and (iii) verbal and non-verbal memory functions are not entirely lateralized. It is argued here that the perirhinal cortex is a key node in a more extensive network mediating protosemantic associative memory. Impairment of this fundamental memory system is a proximal neurocognitive marker of mesial temporal epileptogenesis.

Prevention and management of febrile seizures

Febrile seizures are the most common seizures in childhood and, like all seizures, can be frightening to witness. Therefore, it is not surprising that febrile seizures have been the focus of intense research with an extensive literature describing various preventative measures. In addition, there is also an extensive and sophisticated epidemiological literature delineating the natural history of this disorder in American and British children. For simple febrile seizures, the most common form of this disorder, the epidemiological studies demonstrate a generally benign natural history, making it unlikely that any preventative measure could improve the long term outcome for most children. Children with simple febrile seizures have a slight increased risk of epilepsy, but there are no studies that demonstrate that phenobarbital or other therapy can alter this risk. Daily therapy with phenobarbital or valproic acid can reduce the number of subsequent simple febrile seizures. However, as a recent Practice Parameter from the American Academy of Paediatrics concludes, the risk of adverse effects from daily therapy appears to outweigh the benefit of preventing the short term recurrence of simple febrile seizures. It is possible that in some families, where the occurrence of an additional simple febrile seizure would be particularly distressing, the routine use of oral diazepam during febrile illnesses might be appropriate.

Technical report: treatment of the child with simple febrile seizures

OVERVIEW

Simple febrile seizures that occur in children ages 6 months to 5 years are common events with few adverse outcomes. Those who advocate therapy for this disorder have been concerned that such seizures lead to additional febrile seizures, to epilepsy, and perhaps even to brain injury. Moreover, they note the potential for such seizures to cause parental anxiety. We examined the literature to determine whether there was demonstrable benefit to the treatment of simple febrile seizures and whether such benefits exceeded the potential side effects and risks of therapy. The therapeutic approaches considered included continuous anticonvulsant therapies, intermittent therapy, or no anticonvulsant therapy.

METHODS

This analysis focused on the neurologically healthy child between 6 months and 5 years of age whose seizure is brief (<15 minutes), generalized, and occurs only once during a 24-hour period during a fever. Children whose seizures are attributable to a central nervous system infection and those who have had a previous afebrile seizure or central nervous system abnormality were excluded. A review of the current literature was conducted using articles obtained through searches in MEDLINE and additional databases. Articles were obtained following defined criteria and data abstracted using a standardized literature review form. Abstracted data were summarized into evidence tables (Tables 1 through 7).

RESULTS

Epidemiologic studies demonstrate a high risk of recurrent febrile seizures but a low, though increased, risk of epilepsy. Other adverse outcomes either don't occur or occur so infrequently that their presence is not convincingly demonstrated by the available studies. Although daily anticonvulsant therapy with phenobarbital or valproic acid is effective in decreasing recurrent febrile seizures, the risks and potential side effects of these medications outweigh this benefit. No medication has been shown to prevent the future onset of recurrent afebrile seizures (epilepsy). The use of intermittent diazepam with fever after an initial febrile seizure is likely to decrease the risk of another febrile seizure, but the rate of side effects is high although most families find the perceived benefits to be low. Although antipyretic therapy has other benefits, it does not prevent additional simple febrile seizures.

CONCLUSIONS

The Febrile Seizures Subcommittee of the American Academy of Pediatrics' Committee on Quality Improvement used the results of this analysis to derive evidence-based recommendations for the treatment of simple febrile seizures. The outcomes anticipated as a result of the analysis and development of the practice guideline include: 1) to optimize practitioner understanding of the scientific basis for using or avoiding various proposed treatments for children with simple febrile seizures; 2) to improve the health of children with simple febrile seizures by avoiding therapies with high potential for side effects and no demonstrated ability to improve children's eventual outcomes; 3) to reduce costs by avoiding therapies that will not demonstrably improve children's long-term outcomes; and 4) to help the practitioner educate caregivers about the low risks associated with simple febrile seizures.