Renal dysfunction in children with uncomplicated, Plasmodium falciparum malaria in Tamale, Ghana

Acute Kidney Injuries in Children with Severe Malaria: A comparative study of diagnostic criteria based on serum cystatin C and creatinine levels

Objectives

Serum creatinine levels are often used to diagnose acute kidney injury (AKI), but may not necessarily accurately reflect changes in glomerular filtration rate (GFR). This study aimed to compare the prevalence of AKI in children with severe malaria using diagnostic criteria based on creatinine values in contrast to cystatin C.

Methods

This prospective cross-sectional study was performed between June 2016 and May 2017 at the University of Ilorin Teaching Hospital, Ilorin, Nigeria. A total of 170 children aged 0.5–14 years old with severe malaria were included. Serum cystatin C levels were determined using a particle-enhanced immunoturbidmetric assay method, while creatinine levels were measured using the Jaffe reaction. Renal function assessed using cystatin C-derived estimated GFR (eGFR) was compared to that measured using three sets of criteria based on creatinine values including the Kidney Disease: Improved Global Outcomes (KDIGO) and World Health Organization (WHO) criteria as well as an absolute creatinine cut-off value of >1.5 mg/dL.

Results

Mean serum cystatin C and creatinine levels were 1.77 ± 1.37 mg/L and 1.23 ± 1.80 mg/dL, respectively (P = 0.002). According to the KDIGO, WHO and absolute creatinine criteria, the frequency of AKI was 32.4%, 7.6% and 16.5%, respectively. In contrast, the incidence of AKI based on cystatin C-derived eGFR was 51.8%. Overall, the rate of detection of AKI was significantly higher using cystatin C compared to the KDIGO, WHO and absolute creatinine criteria (P = 0.003, <0.001 and <0.001, respectively).

Conclusion

Diagnostic criteria for AKI based on creatinine values may not indicate the actual burden of disease in children with severe malaria.

Kidney biomarkers in tropical infections: an update

Neglected tropical diseases affect over 1 billion people, and cause 170,000 deaths each year. They result in disability, stigma and disfigurement, and also push families into poverty. Tropical infections can involve the kidney, presenting as a wide variety of ways, varying from transient urinary abnormalities to severe acute kidney injury (AKI). It is important to assess renal function in patients with tropical infections for earlier detection of AKI, appropriate treatment and prevention of Chronic Kidney Disease (CKD) outcome in some of them. There was an exponential increase in research on new kidney biomarkers that were earlier and specific for renal damage but few in the scope of tropical infections. In this review, we focus on kidney biomarkers that are being studied in some of the most prevalent tropical infections such as visceral leishmaniasis, leptospirosis, malaria, schistosomiasis and leprosy. Further studies are needed to evaluate the usefulness of renal biomarkers in the early diagnosis of renal diseases associated with tropical infections.

Autoantibodies and Malaria: Where We Stand? Insights Into Pathogenesis and Protection

Autoantibodies are frequently reported in patients with malaria, but whether they contribute to protection or to pathology is an issue of debate. A large body of evidence indicates that antibodies against host-self components are associated to malaria clinical outcomes such as cerebral malaria, renal dysfunction and anemia. Nonetheless, self-reactive immunoglobulins induced during an infection can also mediate protection. In light of these controversies, we summarize here the latest findings in our understanding of autoimmune responses in malaria, focusing on Plasmodium falciparum and Plasmodium vivax. We review the main targets of self-antibody responses in malaria as well as the current, but still limited, knowledge of their role in disease pathogenesis or protection.

Infections and the kidney: a tale from the tropics

Tropical infections are caused by a variety of bacteria, viruses and parasitic organisms across varying geographical regions and are more often reported in adults than in children. Most of the infections are acute, presenting as a febrile illness with involvement of multiple organ systems, including the kidney. The gamut of renal manifestations extends from asymptomatic urinary abnormalities to acute kidney injury and-albeit rarely-chronic kidney disease. Tropical infections can involve the glomerular, tubulointerstitial and vascular compartments of the kidney. Leptospirosis, malaria, dengue, rickettsial fever and schistosomiasis are the most prevalent tropical infections which affect the kidneys of children living in the tropics. In this review we discuss renal involvement in these most prevalent tropical infections.

Fluid and Volume Monitoring

Background

Fluid resuscitation is not only used to prevent acute kidney injury (AKI) but fluid management is also a cornerstone of treatment for patients with established AKI and renal failure. Ultrafiltration removes volume initially from the intravascular compartment inducing a relative degree of hypovolemia. Normal reflex mechanisms attempt to sustain blood pressure constant despite marked changes in blood volume and cardiac output. Thus, compensated shock with a normal blood pressure is a major cause of AKI or exacerbations of AKI during ultrafiltration.

Methods

We undertook a systematic review of the literature using MEDLINE, Google Scholar and PubMed searches. We determined a list of key questions and convened a 2-day consensus conference to develop summary statements via a series of alternating breakout and plenary sessions. In these sessions, we identified supporting evidence and generated clinical practice recommendations and/or directions for future research.

Results

We defined three aspects of fluid monitoring: i) normal and pathophysiological cardiovascular mechanisms; ii) measures of volume responsiveness and impending cardiovascular collapse during volume removal, and; iii) measured indices of each using non-invasive and minimally invasive continuous and intermittent monitoring techniques. The evidence documents that AKI can occur in the setting of normotensive hypovolemia and that under-resuscitation represents a major cause of both AKI and mortality ion critically ill patients. Traditional measures of intravascular volume and ventricular filling do not predict volume responsiveness whereas dynamic functional hemodynamic markers, such as pulse pressure or stroke volume variation during positive pressure breathing or mean flow changes with passive leg raising are highly predictive of volume responsiveness. Numerous commercially-available devices exist that can acquire these signals.

Conclusions

Prospective clinical trials using functional hemodynamic markers in the diagnosis and management of AKI and volume status during ultrafiltration need to be performed. More traditional measure of preload be abandoned as marked of volume responsiveness though still useful to assess overall volume status.

Epidemiology of acute kidney injury in children worldwide, including developing countries

In this review we summarize the world-wide epidemiology of acute kidney injury (AKI) in children with special emphasis on low-income countries, notably those of the sub-Saharan continent. We discuss definitions and classification systems used in pediatric AKI literature. At present, despite some shortcomings, traditional Pediatric Risk Injury Failure Loss and End Stage Kidney Disease (pRIFLE) and Kidney Disease Improving Global Outcomes (KDIGO) systems are the most clinically useful. Alternative definitions, such as monitoring serum cystatin or novel urinary biomarkers, including cell cycle inhibitors, require more long-term studies in heterogenous pediatric AKI populations before they can be recommended in routine clinical practice. A potentially interesting future application of some novel biomarkers could be incorporation into the "renal angina index", a concept recently introduced in pediatric nephrology. The most reliable epidemiological data on AKI in children come from high-outcome countries and are frequently focused on critically ill pediatric intensive care unit populations. In these patients AKI is often secondary to other systemic illnesses or their treatment. Based on a recent literature search performed within the framework of the "AKI 0by25" project of the International Society of Nephrology, we discuss the scarce and often inaccurate data on AKI epidemiology in low-income countries, notably those on the African continent. The last section reflects on some of the many barriers to improvement of overall health care in low-income populations. Although preventive strategies for AKI in low-income countries should essentially be the same as those in high-income countries, we believe any intervention for earlier detection and better treatment of AKI must address all health determinants, including educational, cultural, socio-economic and environmental factors, specific for these deprived areas.

Acute Kidney Injury Is Common in Pediatric Severe Malaria and Is Associated With Increased Mortality

Acute kidney injury is common in severe malaria and associated with short- and long-term mortality developing in 50% of cases after admission. Cystatin C and BUN are associated with the severity of AKI, are elevated at admission and predict mortality.

Background. Acute kidney injury (AKI) is a well recognized complication of severe malaria in adults, but the incidence and clinical importance of AKI in pediatric severe malaria (SM) is not well documented.

Methods. One hundred eighty children aged 1 to 10 years with SM were enrolled between 2011 and 2013 in Uganda. Kidney function was monitored daily for 4 days using serum creatinine (Cr). Acute kidney injury was defined using the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. Blood urea nitrogen (BUN) and Cr were assessed using i-STAT, and cystatin C (CysC) was measured by enzyme-linked immunosorbent assay.

Results. Eighty-one (45.5%) children had KDIGO-defined AKI in the study: 42 (51.9%) stage 1, 18 (22.2%) stage 2, and 21 (25.9%) stage 3. Acute kidney injury evolved or developed in 50% of children after admission of hospital. There was an increased risk of AKI in children randomized to inhaled nitric oxide (iNO), with 47 (54.0%) of children in the iNO arm developing AKI compared with 34 (37.4%) in the placebo arm (relative risk, 1.36; 95% confidence interval [CI], 1.03–1.80). Duration of hospitalization increased across stages of AKI (P = .002). Acute kidney injury was associated with neurodisability at discharge in the children receiving placebo (25% in children with AKI vs 1.9% in children with no AKI, P = .002). Mortality increased across stages of AKI (P = .006) in the placebo arm, reaching 37.5% in stage 3 AKI. Acute kidney injury was not associated with neurodisability or mortality at discharge in children receiving iNO (P > .05 for both). Levels of kidney biomarkers were predictive of mortality with areas under the curves (AUCs) of 0.80 (95% CI, .65–.95; P = .006) and 0.72 (95% CI, .57–.87; P < .001), respectively. Admission levels of CysC and BUN were elevated in children who died by 6 months (P < .0001 and P = .009, respectively).

Conclusions. Acute kidney injury is an underrecognized complication in young children with SM and is associated with increased mortality.

Monoclonal auto-antibodies and sera of autoimmune patients react with Plasmodium falciparum and inhibit its in vitro growth

The relationship between autoimmunity and malaria is not well understood. To determine whether autoimmune responses have a protective role during malaria, we studied the pattern of reactivity to plasmodial antigens of sera from 93 patients with 14 different autoimmune diseases (AID) who were not previously exposed to malaria. Sera from patients with 13 different AID reacted against Plasmodium falciparum by indirect fluorescent antibody test with frequencies varying from 33-100%. In addition, sera from 37 AID patients were tested for reactivity against Plasmodium yoelii 17XNL and the asexual blood stage forms of three different P. falciparum strains. In general, the frequency of reactive sera was higher against young trophozoites than schizonts (p < 0.05 for 2 strains), indicating that the antigenic determinants targeted by the tested AID sera might be more highly expressed by the former stage. The ability of monoclonal auto-antibodies (auto-Ab) to inhibit P. falciparum growth in vitro was also tested. Thirteen of the 18 monoclonal auto-Ab tested (72%), but none of the control monoclonal antibodies, inhibited parasite growth, in some cases by greater than 40%. We conclude that autoimmune responses mediated by auto-Ab may present anti-plasmodial activity.

Malaria-induced renal damage: facts and myths

Malaria infections repeatedly have been reported to induce nephrotic syndrome and acute renal failure. Questions have been raised whether the association of a nephrotic syndrome with quartan malaria was only coincidental, and whether the acute renal failure was a specific or unspecific consequence of Plasmodium falciparum infection. This review attempts to answer questions about "chronic quartan malaria nephropathy" and "acute falciparum malaria nephropathy". The literature review was performed on all publications on kidney involvement in human and experimental malarial infections accessible in PubMed or available at the library of the London School of Hygiene and Tropical Medicine. The association of a nephrotic syndrome with quartan malaria was mostly described before 1975 in children and rarely in adult patients living in areas endemic for Plasmodium malariae. The pooled data on malaria-induced acute renal failure included children and adults acquiring falciparum malaria in endemic areas either as natives or as travellers from non-tropical countries. Non-immunes (not living in endemic areas) had a higher risk of developing acute renal failure than semi-immunes (living in endemic areas). Children with cerebral malaria had a higher rate and more severe course of acute renal failure than children with mild malaria. Today, there is no evidence of a dominant role of steroid-resistant and chronic "malarial glomerulopathies" in children with a nephrotic syndrome in Africa. Acute renal failure was a frequent and serious complication of falciparum malaria in non-immune adults. However, recently it has been reported more often in semi-immune African children with associated morbidity and mortality.

CYP2C8 and antimalaria drug efficacy

Malaria is a major infectious disease. In the last 10 years it has killed more than 20 million people, mainly small children in Africa. The highly efficacious artemisinine combination therapy is being launched globally, constituting the main hope for fighting the disease. Amodiaquine is a main partner in these combinations. Amodiaquine is almost entirely metabolized by the polymorphic cytochrome P450 (CYP) isoform 2C8 to the pharmacologically active desethylamodiaquine. The question remains whether the efficacy of amodiaquine is affected by the gene polymorphism. Genotype-inferred low metabolizers are found in 1-4% of African populations, which corresponds to millions of expected exposures to the drug. In vivo pharmacokinetic data on amodiaquine is limited. By combining it with published in vitro pharmacodynamic and drug metabolism information, we review and predict the possible relevance, or lack of, of CYP2C8 polymorphisms in the present and future efficacy of amodiaquine. Chloroquine and dapsone, both substrates of CYP2C8, are also discussed in the same context.