Educational review: measurement of GFR in special populations.

IMPORTANCE: Changes in kidney function are typically followed by the sequential estimation of glomerular filtration rate (eGFR). Formulae for eGFR work well on a population basis, but there are well-known conditions where they do not work. OBJECTIVE: The purpose of this review is to summarize the existing literature on special populations in the pediatric age range and provide recommendations on how to estimate GFR in these populations. FINDINGS: The reliability of creatinine depends on muscle mass, while cystatin C (not widely available) is limited by inflammation and changes in protein catabolism. Various dietary factors can alter eGFR. Renal function in neonates changes drastically every day, and there are currently no satisfactory reference intervals for routine pediatric use. Gender effects and conditions such as wasting disease and obesity require alternative ways to obtain eGFR. In oncology patients, chemotherapy may negatively affect renal function, and nuclear GFR measurements may be necessary. For body builders, high muscle mass may lead to underestimation of eGFR using creatinine. CONCLUSIONS AND RELEVANCE: Clinicians should be aware of special populations that may yield misleading eGFRs with conventional creatinine-based formulae, and that the alternative methods may be more appropriate for some populations.

Strategies to reduce line infections in a small child with homozygous familial hypercholesterolaemia who cannot yet receive LDL apheresis.

Patients with homozygous familial hypercholesterolaemia are optimally treated with low-density lipoprotein apheresis. Young patients who do not meet a weight threshold (25 kg) receive regular plasmapheresis. This approach may remove excessive immunoglobulins and vascular access set-up can be challenging. We report the case of a 4 year-old child who exhibited repeated septic infections (5 in 6 months) and had recurrent access issues before two interventions were implemented: (1) the percutaneous central venous line was modified to two implanted paediatric ports, and (2) the patient started receiving two bags of Octaplasma at the end of each plasmapheresis treatment to account for the excessive loss of immunoglobulins. For the paediatric plasmapheresis access port, a 19-gauge Huber needle had to be used for the arterial port to prevent the collapse of the extension. These two simple changes have left the patient infection-free for 9 months.

Barriers to the Implementation of Lipoprotein Apheresis in Canada.

This article details the effectiveness of using lipoprotein apheresis (LA) rather than plasmapheresis in patients with homozygous familial hypercholesterolemia (HoFH), using results from the first HoFH pediatric patient treated with LA in Ontario. We further detail the barriers involved in adhering to international guidelines by implementing this as a first-line treatment for this condition in Ontario, and the potential savings that would be gained with treating the remaining HoFH patients in this province with LA. A primary barrier has been the division of responsibility that exists in Canada, where the delivery of medical services and the delivery of blood products are separated, artificially discounting the price of plasmapheresis and making it seem like the less expensive option. We would like to implement LA as a first-line therapy, to not only improve patient quality of life and outcomes, but to also to potentially save our federal and provincial governments' taxpayer money.

Digital microfluidic platform for the detection of rubella infection and immunity: a proof of concept.

BACKGROUND: Whereas disease surveillance for infectious diseases such as rubella is important, it is critical to identify pregnant women at risk of passing rubella to their offspring, which can be fatal and can result in congenital rubella syndrome (CRS). The traditional centralized model for diagnosing rubella is cost-prohibitive in resource-limited settings, representing a major obstacle to the prevention of CRS. As a step toward decentralized diagnostic systems, we developed a proof-of-concept digital microfluidic (DMF) diagnostic platform that possesses the flexibility and performance of automated immunoassay platforms used in central facilities, but with a form factor the size of a shoebox. METHODS: DMF immunoassays were developed with integrated sample preparation for the detection of rubella virus (RV) IgG and IgM. The performance (sensitivity and specificity) of the assays was evaluated with serum and plasma samples from a commercial antirubella mixed-titer performance panel. RESULTS: The new platform performed the essential processing steps, including sample aliquoting for 4 parallel assays, sample dilution, and IgG blocking. Testing of performance panel samples yielded diagnostic sensitivity and specificity of 100% and 100% for both RV IgG and RV IgM. With 1.8 µL sample per assay, 4 parallel assays were performed in approximately 30 min with <10% mean CV. CONCLUSIONS: This proof of concept establishes DMF-powered immunoassays as being potentially useful for the diagnosis of infectious disease.