Estimated GFR Derived From Plasma Creatinine by Mass Spectrometry (MSMS) Is A Reliable Measure of Renal Function During the Hyperfiltration Phase In Sickle Cell Disease (SCD)

The hypothesis is that a height based eGFR formula using creatinine measured by mass spectrometry is a reliable measure of GFR in children with SCD.

The kidney is a particularly sensitive to hypoxia and renal failure is a major cause of morbidity and mortality in SCD. Children with SCD commonly hyper filtrate, thus making it difficult to establish a reliable Glomerular Filtration Rate (GFR) measure. It is essential to correctly assess the GFR, in order to identify when it begins to fall back towards normal and then starts to decline. Reporting of estimated glomerular filtration rate (eGFR) derived from plasma creatinine (pCr) measurements is now recommended for the classification and monitoring of patients with chronic kidney disease. The new MDRD formula requires the use of pCr methods traceable to stable isotope dilution mass spectrometry (MS). In children the recommendation is to use one of the formulae based on height (Ht), e.g. Schwartz et al¹, Morris et al², both of which were derived using traditional Jaffe creatinine methodology; eGFR = 40 × Ht (cm)/pCr (μmol/l). The introduction of MS traceable creatinine methods requires a review of the k factor. This correlation has never been validated in hyper filtration/or children with SCD.

43 HbSS patients, age range 5–20yrs, attending the Evelina Children's Hospital were studied, including transfused and non-transfused patients. The plasma samples were also used for the measurement of plasma creatinine by stable isotope dilution mass spectrometry. eGFR was calculated using k=31.

Inutest GFR ranged from 70–175 ml/min/1.73m². There was significant correlation between eGFR and inutest GFR (P<0.01, r=0.68).

These preliminary data suggest that eGFR should prove valuable in monitoring GFR in children with SCD, even during hyper filtration, providing the constant is appropriately adjusted for the analytical method of creatinine.

Inusa:Novartis: Research Funding.